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Reply: Bridge dynamics and dynamic amplification factors – a review of analytical and experimental findings

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... The DAF for repetitive loading of heavy vehicles, relevant to fatigue, may be different. The fatigue-relevant DAF depends on many aspects [58], which makes a reliable prediction with analytical or numerical models difficult [59]. Paultre et al. [59] therefore advocate using measurements. ...
... The fatigue-relevant DAF depends on many aspects [58], which makes a reliable prediction with analytical or numerical models difficult [59]. Paultre et al. [59] therefore advocate using measurements. One of the most important aspects is the road roughness [60], and many authors have therefore applied planks or other obstacles to evaluate the dynamic amplification. ...
... Fig. 5(a) indicates a weak positive trend between and . It may be caused by the fact that the first resonance frequency of the structure tends to reduce with increasing span [59]. However, because of the low value and the low scatter of , this trend is further ignored. ...
Article
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This paper presents a probabilistic framework to derive the safety factors for fatigue of steel and composite steel concrete road bridges. Engineering models are used for the design and the safety factor is derived in such a way that the design meets the target reliability set by international Eurocode and ISO standards, estimated using measured data and advanced probabilistic models. Engineering model uncertainties and dynamic amplification factors are established through comparison of measurements and models. The value of visual inspections is quantified based on observations from practice and expert opinions. The safety factors are derived for Eurocode’s Fatigue Load Model 4 and Eurocode’s tri-linear S-N curve. The study shows that the safety factors for fatigue as currently recommended by the Eurocodes need to be raised.
... Moving vehicles, such as high-speed trains (HSTs), exert dynamic loads on a bridge owing to the interaction between the vehicle and bridge, thereby magnifying the bridge response [1][2][3][4][5]. A dynamic amplification factor (DAF), which represents a dynamic increment with respect to the static response, is widely utilized in the bridge engineering to identify the dynamic effect induced by moving vehicles on a bridge [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. DAF has been extensively evaluated for various purposes, including railway bridge design and condition assessment of existing bridges [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. ...
... A dynamic amplification factor (DAF), which represents a dynamic increment with respect to the static response, is widely utilized in the bridge engineering to identify the dynamic effect induced by moving vehicles on a bridge [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. DAF has been extensively evaluated for various purposes, including railway bridge design and condition assessment of existing bridges [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. ...
... In the past, DAF was assessed from the maximum values of the total and static responses [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The identification of total and static responses is a significant prerequisite for determining DAF. ...
Article
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HSR bridges are exposed to repetitive dynamic loading induced by the passage of high-speed trains (HSTs). Moving loads from HSTs can amplify the dynamic responses of bridges. The dynamic amplification factor (DAF) has been measured by the ratio between maximum dynamic to static responses of bridges when train passes over it. It is difficult to measure the static response during train operation. This study proposes a new framework to assess the DAF of HSR bridges using a multi-sensor fusion technique, which separates the total bridge response into the static and dynamic responses using a single measurement. The proposed method generates time-varying dynamic magnification by calculating the ratio of extracted dynamic response to static response at each measured time step. This method was applied to an HSR bridge under resonance conditions in South Korea and provides a clear understanding of how HSR bridges in resonance.
... W ocenie wpływów dynamicznych drgań podłoża gruntowego na konstrukcję budynku wykorzystano pracę [16].Na podstawie wykresów przemieszczeń wybranych węzłów modelu konstrukcji określono przemieszczenia dynamiczne ...
... Dynamiczny współczynnik wzmocnienia (the dynamic amplification factor) opisuje wzór [16]: DAF = R dyn / R sta We wszystkich przeanalizowanych przez nas węzłach wiernego modelu konstrukcji wartość współczynnika DAF zawierała się w przedziale 1.03 ÷ 1.07. ...
... R dyn = U y dla t = 1.60 s , R sta = U y.lt dla t = 1.60 s ,R dyn = 0.022850 mm , R sta = 0.022048 mm DAF = 0.022850 / 0.022048 = 1.04 W wyniku analizy wykresów przemieszczeń węzłów wiernego modelu konstrukcji poddanej wymuszeniu kinematycznemu zostały określone wartości dynamicznego współczynnika wzmocnienia DAF [16]. Wartość te zawierają się w przedziale 1.03 ÷ 1.07. ...
Article
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An accelerated development of urban communication infrastructure, especially that of railway, forces search for new space for investment. The area of communication infrastructure interpenetrates usable space creating mutual symbiotic interaction. This development carries the growth of influence on the surrounding areas. This article presents the influence of a railway infrastructure on a newly designed commercial and office center situated on the flyover over the railway track, as well as on technical devices and people staying there. The aim of the research and the analysis was to gain information about acceleration spectrum of the response of the building that is situated near the railway track and thus to forecast vibration timings of a designed building together with kinematic excitation at the level of foundation. For static strength calculations, the research investigated the influence of subsoil vibrations caused by rolling stock on a dynamic stress increase in the structure as well as on the specification of a dynamic factor and thus on taking into consideration the growth and stress variation in design approach. The analysis of the dynamic factor at the designing level enables us to eliminate the influence of vibration exposure by introducing vibration damping system in the most optimal location of vibration centre.
... (2) into Eq. (1), and assuming the initial displacement and velocity of the bridge vibration are zeros, the moving load-induced deflection response can be decomposed into the moving-frequency component u m due to moving load and the natural-frequency component u n due to bridge vibration [Paultre et al. (1992)] ...
... The parameters b i,j and Δλ i in Eqs. (9) and (10) can be solved based on the eigenvalue equation of the bridge in Paultre et al. [1992]. The natural frequency of the damaged bridge ω d i can be determined accordingly. ...
... Similarly, to the intact state, substituting Eq. (7) into Eq. (1), and assuming the initial displacement and velocity of the bridge vibration to be zeros, the moving load-induced deflection response of a damaged bridge can be derived as [Paultre et al. (1992)] ...
Article
The critical signal component extracted from the bridge response caused by a moving vehicle is normally used to construct damage index for damage detection. The dynamic response of bridges subjected to moving vehicle includes several components, among which the quasi-static component reflects the inherent characteristics of the bridge. In view of this, this paper presents a bridge damage detection method based on quasi-static component of the moving vehicle-induced dynamic response. First, damage-induced changes of the natural-frequency component, moving-frequency component and quasi-static component responses are investigated via a simply-supported beam bridge. The quasi-static component response is proved to be less sensitive to the moving velocity of the load and more suitable for damage detection. Subsequently, a quasi-static component response extraction method is proposed based on analytical mode decomposition (AMD) and moving average filter (MAF). The extracted quasi-static component response is further employed to localize and quantify damages. Finally, numerical simulations are conducted to examine the feasibility, accuracy and advantages of the proposed damage detection method. The results indicated that the proposed method performs well in different damage scenarios and is insensitive to the moving velocity of the load and road roughness.
... Armii Ludowej16, 00-637 Warsaw, Poland, e-mail: m.ataman@il.pw.edu.pl experimental methods for the determination of the dynamic coefficients in road bridges can be found in [9]. ...
... Among the scientific studies devoted to this problem, one should also mention Fryba [5], Yang et al. [15] and paper [14], Galdos [6], Paulter [9], Zhang [16], and others. ...
... Wśród prac naukowych poświęconych temu zagadnieniu należy wymienić również monografię Fryby [5], monografię Yanga i innych [15] i jego pracę [14], prace Galdosa [6], Paultera [9], Zhanga [16] oraz inne. ...
Article
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The impact of a moving load speed on the dynamic overload of beams, assuming that the track of the load has no unevenness, is examined. First the problem of a visco-elastic beam on a Winkler foundation subjected to a force moving at a constant speed will be solved. Using the Bubnov-Galerkin method, the deflections of the beam, and then the bending moments and shear forces will be determined. The solution of the problem will be obtained both for the case of a forced vibration and the case of a free vibration after the moving force has left the beam. Using these solutions, dynamic amplification factors will be determined for the deflections, bending moments, and shear forces, which are different for the two cases. The magnitude of the amplification factors increases and decreases alternately as a function of the speed. In the case of a single force on a beam, the dynamic overloads are limited, and do not exceed 60%. There is no resonance phenomenon in the beam subjected to the single moving force. The dynamic amplification factors determined in this way can be used as correction coefficients when designing engineering structures subjected to moving loads by static methods.
... The IM is defined as an increment in the static load to account for the dynamic effects of moving vehicles. Therefore, the maximum dynamic response of the moving vehicles can be obtained as follows [48]: ...
... Green [49] also presented an interesting example of defining a zero DA for large dynamic responses based on the current definition of DA, which suggests that DA might not be an effective measure for considering dynamic effects in fatigue design. In addition, compared with other parameters, such as the first natural frequency of the bridge, vehicle speed, vehicle suspension systems and initial vehicle vibrations, which have effects on the dynamic amplification factor (DAF) or DA, the road surface profiles were found to have a tremendous effect on DAF or DA [48], [50], [51]. Even though the deck surface roughness is considered as a major factor for vehicular dynamic effects on bridges, estimating the effects of long-term time-variant deck deteriorations at the bridge design stage is still challenging. ...
... The reliability-based dynamic amplification factor for the revised equivalent stress range for life cycle bridge fatigue design (DALC) is defined in Eq. (12). For comparison, the definition of the dynamic amplification factor (DAF) based on maximum responses [48] is shown in Eq. (13). (12) where S st is the maximum static stress range due to the passage of the live loads without considering the dynamic effects. ...
Article
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Dedicated to Prof. Dr. Akimitsu Kurita on his 70th birthday In current bridge design codes or specifications, the dynamic effects of vehicles are considered by using a dynamic amplification factor (DAF) or dynamic load allowance (IM). However, a DAF is defined based on the ratio of the maximum dynamic load responses to the static load responses, and it is more appropriate for maximum value-based strength design. For fatigue design, stress cycles other than the maximum stress ranges could contribute to fatigue damage accumulations. Meanwhile, on the capacity side, a reduction in fatigue strength due to structural deterioration, which is related to local environmental conditions, including temperature, humidity, etc., could introduce more uncertainties into structural safety and reliability evaluation. However, such multiple stress range effects and structural deterioration are not included in current bridge fatigue design. To evaluate the vehicular dynamic effects for the life cycle fatigue design of short-span bridges, the present study proposes a new dynamic amplification factor for life cycle bridge fatigue design (DALC), which is defined as the ratio of the life cycle nominal live load stress range to the maximum static stress range. In contrast to other traditionally defined dynamic factors, the newly defined DALC includes information about both the structural loading and the structural capacity. Therefore, the multiple stress cycles from vehicle-induced vibrations and the structural deteriorations from road surface conditions and corrosion of structural members are included. Parametric studies of DALC were carried out for multiple parameters and variables in the bridge's design life cycle, for instance, possible faulting days in each year, fatigue strength exponent, corrosion parameters and corrosion level. The stochastic properties and uncertainties from these variables are also considered in the DALC calculation.
... The first vibration period (T) of the three case-study bridges is calculated as explained in Appendix A and is shown in Figure 7 for a range of bridge spans (L). The plausible range in Figure 7 is obtained enveloping the empirical data from Paultre et al. (1992). The frequencies (f = 1/T) are compared with literature values and an empirical formulation available in the literature (i.e., f = 82L-0.9; ...
... The composite bridge has a systematic lower vibration frequency with respect to the reinforced concrete bridges for the entire range of investigated span values. F I G U R E 7 Fundamental frequencies versus span length for the three case-study bridges compared to empirical literature data and formulation (Paultre et al., 1992) Figure 8 shows the comparison between the analytical solutions proposed by Frýba (2013) for a traveling load/load-mass on a simply supported beam (see Appendix B) and the numerical solution for a traveling load proposed in this study solved with OpenSees. The results that can be used to identify the velocity leading to resonance are provided in terms of maximum mid-span displacement as a function of the nondimensional traveling velocity of the force. ...
Article
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The rigorous modeling of traveling loads on bridges in a dynamic regime is not an easy task as the traveling load contributes to the dynamic of the structural system with its mass and damping. In this paper, a simplified approach for traveling loads on bridges in dynamic regime is proposed. The main simplification consists in neglecting the traveling mass. The validity of the proposed simplification is checked with a sensitivity analysis considering a few realistic case‐study bridges. The ranges of velocity and traveling‐force/bridge‐weight ratio are identified. Eventually, the proposed methodology is applied to two case studies, (i) an existing Italian reinforced concrete viaduct and (ii) a pedestrian bridge. The applications show that the proposed simplified approach can be applied to a range of civil engineering problems such as the quantification of the structural reliability of existing structures or the assessment of pedestrian comfort.
... It is custom in design codes to specify a Dynamic Amplification Factor (DAF), larger than one, which is multiplied by the static load effects, , to represent the total load effect, (Paultre, Chaallal & Proulx, 1992;O'Connor & OBrien, 2003;González, Znidaric, Casas, Enright, OBrien, Lavric & Kalin, 2009;Ludescher & Bruhwiler, 2009;OBrien, Rattigan, González, Dowling & Žnidarič, 2009;Caprani, 2013Caprani, , 2017Deng, Yu, Zou & Cai, 2015). The DAF can be expressed as per Equation 1. ...
... Design codes typically specify a DAF based on a study of light and heavy vehicles. It has been shown that this approach is conservative as heavier vehicles, which govern the maximum load effects, tend to cause the lowest dynamic amplification (Paultre et al., 1992;O'Connor & OBrien, 2003;González et al., 2009;Ludescher & Bruhwiler, 2009;OBrien et al., 2009;Caprani, González, Rattigan & OBrien, 2011;Caprani, 2013Caprani, , 2017Deng et al., 2015). The codes therefore fail to recognise the decreased probability of the maximum static load effects occurring simultaneously with the maximum dynamic amplification, leading to conservative results. ...
... where DLA = dynamic load allowance; R dyn = maximum dynamic response; and R sta = maximum static response. The estimation of the static response can be obtained by: (1) conducting a quasi-static test where vehicles move across the bridge at a low speed between 5-16 km/h; (2) filtering the measured dynamic response with a low-pass filter to eliminate the dynamic components of the signal; and (3) using finite element models (FEM) to calculate the static response when the vehicle weight and loading position are known (Paultre et al. 1992, Deng et al. 2015. In this study, the first and third options were selected and compared to estimate Bridge A7957's DLA. ...
... Dynamic load allowance vs. fundamental frequency(OMTC 1983, Paultre et al. 1992. ...
Conference Paper
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The load rating of a bridge can be obtained by means of field load testing. The dynamic load allowance or impact factor is one of the parameters used to establish a bridge’s flexural capacity during the rating evaluation process. The focus of this study centered on comparing Bridge A7957’s dynamic load allowance obtained by experimental and analytical methods proposed in three different design and evaluation codes. To attain this goal, Bridge A7957 was instrumented with accelerometers at different locations. For different dynamic tests, the spans’ response was measured with the accelerometers and a laser vibrometer. The dynamic load allowance was obtained experimentally and analytically using current design and evaluation codes. The impact factors obtained analytically resulted in larger values compared to the experimental results. This difference might have repercussions in the strength evaluation results of bridge structures.
... (2) Where Rdyn = maximum dynamic response and Rsta = maximum static response. According to Paultre et al. (1992, McLean et al. (1998 and Deng et al. (2015), the estimation of the static response can be obtained by: (1) conducting a quasi-static test where vehicles move across the bridge at a low speed between 5-16 km/h; (2) filtering the measured dynamic response with a low-pass filter to eliminate the dynamic components of signal; and (3) using finite element models (FEM) to calculate the static response when the vehicle weight and loading position are known. In this study, the first option was employed to estimate Bridge A7957's DLA. ...
... DLA vs. fundamental frequency [data from OMTC (1983),Paultre et al. (1992)]. ...
Conference Paper
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The load capacity of a bridge can be obtained by means of a series of diagnostic load tests. The dynamic load allowance or impact factor is a parameter used to establish a bridge's flexural capacity during the capacity evaluation process. Bridge A7957 was built using normal-strength self-compacting concrete and high-strength self-compacting concrete. The objective of this study was to compare Bridge A7957's dynamic load allowance obtained by experimental and analytical methods proposed in three different design and evaluation codes. To attain this objective, Bridge A7957 was instrumented with accelerometers at different locations. For different dynamic tests, the spans' response was measured with accelerometers and a laser vibrometer. The dynamic load allowance was obtained experimentally and analytically using current design and evaluation codes. The impact factors obtained analytically resulted in larger values compared to the experimental results. This difference might have repercussions in the assessment results of bridge structures.
... In case of road bridges the method of obtaining quasi static displacements history by means of filtering was presented in (Paultre et al. 1992). According to this publication, a low pass digital filter, applied to the recorded data, is used to smooth out the dynamic frequencies in the signal. ...
... where the static frequency is close to the natural frequency of the first vibration mode. This result is compatible with (Paultre et al. 1992), where it was found that when the static frequency becomes equal to (and even higher than) the one corresponding to the first vibration mode of the bridge, then dynamic components of the signal can no longer be removed without impact on the static component. However, in this case the application of the FIR filter led to the best result: the relative deviation was close to 0%. ...
... In addition, the experimental impact factors corresponding to different truck speeds are listed in row 4. The experimental dynamic amplification factor, DAF was estimated with Eq. (4). Table 1 (rows [6][7][8]. Finally, the dynamic load allowance estimated as a function of the bridge's fundamental frequency (OHBDC 6 approach) is presented in Table 1 (row 9). The maximum value of the experimental impact factor corresponds to 0.175 and was produced when the test truck was driven over the bridge at a maximum speed of 96 km/h (60 mi/h) (see Table 1 and Fig. 12). ...
... Dynamic load allowance (DLA) vs. fundamental frequency6,7 ...
Article
The load carrying capacity of a bridge structure can be effectively assessed by means of a field load testing. An important parameter used to determine the load rating of a bridge structure is the dynamic load allowance (impact factor). Bridge A7957 is the first bridge superstructure implementation built by the Missouri Department of Transportation (MoDOT) employing normal-strength self-consolidating concrete (NS-SCC) and high-strength self-consolidating concrete (HS-SCC). The aim of this study was to evaluate the impact factor of Bridge A7957 obtained by experimental and analytical methods. To achieve this goal, Bridge A7957 was instrumented with accelerometers at different span locations. For different dynamic load tests, the dynamic response of each span was recorded with the accelerometers and a laser vibrometer. The impact factor was computed using three different design codes and was compared to field measured impact factors. It was found that the impact factors estimated with the design codes provided conservative values regarding the structural response of the bridge under experimental dynamic loads. This difference has direct implications on the rating factor of a bridge.
... The experimental study of the vibration characteristics of structural systems is an important element in our efforts to understand and control many vibration phenomena encountered in design. Very often, tests are performed on a complex structure with the objective of obtaining an empirical description of its dynamic behavior, or providing verification for an analytical or a numerical structural model [1][2][3][4][5]. To quantify the dynamic response of a given structure, the determination of its intrinsic dynamic properties such as B B. R. Nana Nbendjo nananbendjo@yahoo.com 1 Laboratory of Modelling and Simulation in Engineering, Biomimetics and Prototypes, Faculty of Science, University of Yaoundé I, P.O. ...
... To quantify the dynamic response of a given structure, the determination of its intrinsic dynamic properties such as B B. R. Nana Nbendjo nananbendjo@yahoo.com 1 Laboratory of Modelling and Simulation in Engineering, Biomimetics and Prototypes, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon natural frequencies, vibration modes and damping, etc., is of particular importance. ...
Article
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In this paper, we sought to develop a valid theoretical model of two bridges coupled via their dynamic environment modelled as a linear viscoelastic Winkler foundation. Analytical, numerical and experimental study of the dynamic response of the two bridges are explored in the cases where they are submitted to sinusoidal excitation and periodic impulsive force. The effects of the close environment and the distance between the two bridges on the amplitude of vibration of each beam bridge is pointed out.
... In case of road bridges the method of obtaining quasi static displacements history by means of filtering was presented in (Paultre et al. 1992). ...
... In order to analyse the effectiveness of the filtering method in case of railway bridges the three kinds of low pass filters (Smith 2003, Lyons 2010 The results in case of the Bessel filter and FIR filter were analysed by means of three cutoff frequencies: − fc1 equal to the average of the so called static frequency (vmax/L, where vmax is the train speed and L is the span length) and first fundamental frequency of free vibration; − fc2, in case of which no free vibration was observed after the filtration when the train left the tested bridge, − fc3, in case of which value dsta was obtained, which was consistent with the extreme value dv10 registered during the train ride at the quasi-static speed of 10 km/h. In case of moving average filtration method the results were analysed by using three averaging periods: − Tave1 equal to the inverse of average from the so called static frequency (vmax/L where vmax is the train speed and L is the span length) and first fundamental frequency of free vibration; − T ave2, , in case of which free vibration was obtained after the filtration when the train left the tested bridge, − T ave3, , in case of which value dsta was obtained, consistent with the extreme value dv10 registered during the train ride at the quasi-static speed of 10 km/h. ...
Conference Paper
ABSTRACT: The paper presents possible applications of digital signal processing techniques for extrapolation of measurement results during dynamic testing of high speed railway bridges. Extrapolation concerns calcula-tion of measurement results of high and low speed train rides, which either exceed or do not reach the speed values registered during the conducted bridge testing. The extrapolation of values under lower speed is pre-sented with the example of quasi-static value calculation made on the basis of displacements registered during train rides at the maximum permissible speed. This activity is applied mainly to the calculation of dynamic amplification factor. The extrapolation of values under higher speed is presented with the example of calcula-tion of displacements at a speed reaching 125% of the measured values. The applied extrapolation methods are presented with the examples of research conducted on two bridges.
... Methodology for obtaining and evaluating dynamic characteristics for dynamic load testing.84 ...
Book
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Using data obtained from the dynamic load testing of bridges a method was developed to evaluate level of the dynamic performance without performing a dynamic load test. In this method a dynamic index of the bridge is calculated. Dynamic index allows to evaluate the dynamic performance level of existing and new structures taking into account such bridge parameters as span length / height ratio, natural frequency, vibration damping coefficient, relative deflection and international roughness index IRI. Dynamic index method can be used by bridge owners and maintainers to determine the dynamic potential of a particular bridge. The maximum allowable values of the dynamic amplification factor for standard prestressed concrete beam bridges were determined. These values were calculated for maximum allowed traffic load in Latvia. The obtained results can be used for the safety assessment of existing and reconstructed reinforced concrete beam bridges.
... Estudios recientes han reconocido la necesidad de evaluar el factor de impacto dinámico en términos tanto de la frecuencia fundamental del puente como de algunas características del tráfico [74]. Con ello, en algunos casos se tienen valores de hasta 0.8, mientras que valores más comunes caen entre 0.2 y 0.4. ...
Technical Report
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The main applications of the dynamic analysis of bridges, are related with structural damage evaluation. Thus, bridge and vehicle parametric analysis are necessary in order to identify which are the main causes of bridge structural damage. The main analysis tools available are outlined in this work. They cover a wide range of methods, going from the traditional Fourier analysis to the more recently wavelet analysis. Advantages and limitations of these bridge analysis methods are discussed. Research carried out at the Mexican Transport Institute is presented and includes both, experimental and theoretical approaches. Experimental work is reported for a “tridilosa” type bridge. In this case, Fourier and wavelets analysis methods were used. Theoretical work is also reported related with the paremetric evaluation of vehicle-bridge interaction, using dynamic equations obtained through finite element analysis.
... Except the numerical analyzes and theoretical methods, a large number of¯eld tests was carried out from 1950s to 1980s to support the development of the bridge design codes. 15,16 The test results showed that DAFs were around 1.30 and smaller than 1.75 for most cases. ...
Article
The empirical formulas of dynamic amplification factor (DAF) specified in current bridge codes only consider the span or fundamental frequency of reinforced concrete (RC) girders in highway. Although investigations have been carried out on different bridges with considering the road roughness, vehicle–bridge interactions and travelling velocity, but most of them have been done numerically. In this study, experimental study of DAF was carried out on three simple-supported RC beams with different fundamental frequencies and different damage stages, i.e. without damage, cracked and yielded. Impulse hammer with four hammer heads of different hardness, i.e. black, red, green and brown, were used to generate impact forces with increasing duration. The impact tests were first carried out on the RC beams without any damage by impact hammer with different hammer heads. Then the RC beams were loaded by a concentrated static force at the mid-span to crack. Impact tests with different hammer heads were repeated on the cracked RC beams. Finally, the cracked beams were further loaded by a concentrated static force to yield of the longitudinal reinforcement. The impact tests were repeated on the yielded beams again. Load cells installed at the supports of the RC beams were used to measure the reaction force generated by the hammer, then DAF was calculated directly by dividing the peak reaction force with the peak impact force. Data obtained from tests, theoretical analysis and specification in codes were compared to examine the DAFs. Results show that the ratio of duration of the impact force and the period of the beams performed a significant effect on the DAFs of the beams.
... In recent years, many useful conclusions have been obtained on the coupling vibration of different bridge types, such as metro train-bridge, short-span slab bridge, composite steel bridge, and so forth [9][10][11][12][13]. e DLA is the most important factor in the dynamic performance of bridges due to moving vehicles. erefore, the development of the vehicle-bridge coupled vibration and DLA has been summarized by many researchers at different times, which is very meaningful for other researchers [14][15][16]. However, few researchers have focused on the differences in the DLA among each component and among various responses [17]. ...
Article
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Dynamic load allowance (DLA) is a key factor for evaluating the structural condition of bridges; however, insufficient research has been performed regarding the characteristics of DLA in concrete-filled steel tube (CFST) arch bridges. To address this issue, based on an actual CFST arch bridge, the DLA characteristics of bridges are investigated numerically in this study. First, aiming at different structural components, such as the arch rib, main girder, and suspenders, the DLA values obtained at various locations of different structural components are compared in detail, and then the changing regulations of the DLA, considering the influence of different vehicle speeds and various extents of pavement roughness, are summarized and analyzed. Additionally, the relationship between the different DLAs obtained by using the different response indices, that is, displacement, bending moment, and axis force of structure, is investigated. Finally, some conclusions that are significantly beneficial for evaluating or detecting the condition of CFST arch bridges are drawn.
... Thus, DAFs are defined as dynamic-to-quasi static peak deflection due to the dynamics of moving loads. A solid literature review on DAFs of road bridges for vertical motion can be found in [7]. Currently, there is lack of sufficient knowledge on the UHS Hyperloop trains, and hence, no design recommendations exist to design bridges and accommodate the nextgeneration UHS transport system. ...
Conference Paper
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The ultra-high-speed (UHS) Hyperloop is the next-generation mode of passen-ger/freight transportation, and is composed of a tube or a system of tubes through which a pod travels free of friction. The entire system must be supported by piers (multi-span viaducts), where the tubes act as the bridge deck. The UHS moving Hyperloops can exert large dynamic effects to the supporting pier-deck system both vertically and laterally. Particularly, asymmetric Hyperloop loading can generate significant lateral vibrations. Therefore, for safe design of a bridge pier-deck system for UHS trains, it is of great importance to explore dynamic interaction of bridge deck and piers under UHS moving Hyperloops. Hence, this paper analytically summarizes the dynamic amplification factors of the Hyperloop-deck-pier system for vertical and lateral vibrations. It was found that the UHS Hyperloop trains result in higher dynamic effects compared to the high-speed trains.
... Seismic load is also a major concern for a structural engineer when designing the Bridge. Due to its long span and hanging deck and sky touching towers, Cable Suspension Bridge is likely to take huge impact in case of seismic excitation [18][19][20][21]. ...
Conference Paper
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A Cable Suspension Bridge is a class of bridge in which the deck/stiffening girder is hung by the support of suspension cables suspenders. Cable suspension bridge can be constructed over large spans and works on the mechanism of the simply supported beam. Components of the cable suspension bridges are deck, stiffening girder, suspenders, main cable, pylon and anchorage block. The objective of the present study is to present an overview of the structural behaviour of different components of cable suspension bridge with respect to aerodynamic and seismic effect. Effects such as Motion Induced flutter, Vortex Induced Vibration instability and Turbulence Induced Buffeting are experienced by Long Cable Suspension Bridges. The earth's longest Cable Suspension Bridge, at present Akashi Kaikyo Bridge connect with a span range of 1991m is in Japan. Super long-range spans require a propelled comprehension of the wind-bridge communication to fulfil the expanding wellbeing and financial needs.The seismic examination of long-range spans subjected to various ground excitations is an imperative issue. The conventional response spectrum technique disregards the spatial impacts of ground movement, and thusly may result in faulty ends. The irregular vibration approach has been viewed as more dependable. Lamentably, up until this point, computational troubles have not yet been satisfactorily resolved.
... Seismic load is also a major concern for a structural engineer when designing the Bridge. Due to its long span and hanging deck and sky touching towers, Cable Suspension Bridge is likely to take huge impact in case of seismic excitation [18][19][20][21]. ...
Conference Paper
A Cable Suspension Bridge is a class of bridge in which the deck/stiffening girder is hung by the support of suspension cables suspenders. Cable suspension bridge can be constructed over large spans and works on the mechanism of the simply supported beam. Components of the cable suspension bridges are deck, stiffening girder, suspenders, main cable, pylon and anchorage block. The objective of the present study is to present an overview of the structural behaviour of different components of cable suspension bridge with respect to aerodynamic and seismic effect. Effects such as Motion Induced flutter, Vortex Induced Vibration instability and Turbulence Induced Buffeting are experienced by Long Cable Suspension Bridges. The earth's longest Cable Suspension Bridge, at present Akashi Kaikyo Bridge connect with a span range of 1991m is in Japan. Super long-range spans require a propelled comprehension of the wind-bridge communication to fulfil the expanding wellbeing and financial needs.The seismic examination of long-range spans subjected to various ground excitations is an imperative issue. The conventional response spectrum technique disregards the spatial impacts of ground movement, and thusly may result in faulty ends. The irregular vibration approach has been viewed as more dependable. Lamentably, up until this point, computational troubles have not yet been satisfactorily resolved.
... Thus, DAFs are defined as dynamic-to-quasi static peak deflection or stress caused by the dynamics of moving loads. A solid literature review on DAFs of road bridges for vertical motion can be found in (Paultre et al. 1992). ...
Article
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The next generation of ultra-high-speed (UHS) trains, known as Hyperloop and TransPod, are aerospace type vehicles designed to carry passengers. The UHS employs a vehicle capsule within a protected vacuum tube deck, supported by reinforced concrete piers (i.e. multi-span viaduct). The tube environment allows multiple UHS vehicles to run in parallel simultaneously (i.e. twin tube deck) where asymmetric train loading will result in a large dynamic unbalanced moment on the piers. Therefore, exploring the lateral dynamic interaction of bridge deck (twin tube) and piers under such an unbalanced moment is an extremely important factor for analysis of viaducts under dynamic UHS train loading. Hence, this paper analytically addresses the dynamic bridge deck-pier interaction under UHS train loading for lateral vibration.
... The results showed that most DLAs of the six bridges were less than or nearly equal to those calculated by the AASHTO impact equation. Paultre et al. (1992Paultre et al. ( , 1993 and Green (1993) pointed out that the reason why some disagreement exists between provisions of various national bridge codes was that DLA depends, in addition to the maximum span or the natural frequency, on many other parameters that were difficult to take into account with reasonable accuracy. Chang and Lee (1994) theoretically studied vibration behavior of simple-span highway girder bridges with rough surfaces due to heavy trucks. ...
Article
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The main objective of this paper is to study the dynamic load allowance (DLA) calculation methods for bridges according to the dynamic response curve. A simply-supported concrete bridge with a smooth road surface was taken as an example. A half-vehicle model was employed to calculate the dynamic response of deflection and bending moment in the mid-span section under different vehicle speeds using the vehicle-bridge coupling method. Firstly, DLAs from the conventional methods and code provisions were analyzed and critically evaluated. Then, two improved computing approaches for DLA were proposed. In the first approach, the maximum dynamic response and its corresponding static response or its corresponding minimum response were selected to calculate DLA. The second approach utilized weighted average method to take account of multi-local DLAs. Finally, the DLAs from two approaches were compared with those from other methods. The results show that DLAs obtained from the proposed approaches are greater than those from the conventional methods, which indicate that the current conventional methods underestimate the dynamic response of the structure. The authors recommend that the weighted average method based on experiments be used to compute DLAs because it can reflect the vehicle's whole impact on the bridge.
... As an example, often we note a small but evident lowering of the zero-line after the passage of the carriage that can persist even during the next passage. A more robust definition of IM has been discussed by Paultre [26]. It does not require the knowledge of the zero-line, and it takes into account both negative and positive deflections. ...
Article
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The dynamic impact factor (IM) is a widely accepted parameter to account for the effect of vehicles on bridges. An accurate evaluation of this IM is of paramount importance in bridge engineering, both for designing safe and economical new bridges, and for the assessment of the existing ones. At the state of the art, the current procedure for the experimental assessment of the IM of a bridge relies upon the deployment of a sensor network. The aim of this article is to propose the use of a remote sensor, the interferometric radar, for assessing the IM without the deployment of any sensor on the bridge, with evident advantages in terms of cost, time and safety of the workers. Two different case studies of bridges in Northern Iran are reported. In both cases the interferometric radar has been demonstrated an effective and reliable measurement equipment for this kind of in-field assessment.
... where DLA exp = experimental dynamic load allowance; Ddyn max = maximum dynamic (measured) vertical deflection (mm); and Dsta max = maximum static deflection (mm). Some researchers 19,20 have stated that the maximum static response of a bridge can be obtained by (1) conducting a quasi-static test where vehicles move across the bridge at a low speed between 5-16 km/h (3-10 mi/h); (2) filtering the measured dynamic response with a low-pass filter to eliminate the dynamic components of signal; or (3) using finite element models (FEM) to calculate the static response when the vehicle weight and loading position are known. In this study, the first option was used to obtain Bridge A7957's DLA (i.e., the values of the Ddyn max and Dsta max were recorded with the RSV-150 and used to estimate the DLA exp ). ...
Article
Self-consolidating concrete (SCC) has emerged as an alternative to build stronger structures with longer service life. Despite the advantages of using SCC, there are some concerns related to its service performance. The effect of a smaller coarse aggregate size and larger paste content is of special interest. It is fundamental to monitor the response to service loads of infrastructure employing SCC in prestressed concrete members. Bridge A7957 was built employing normal-strength and high-strength self-consolidating concrete in its main supporting members. The diagnostic test protocol implemented in this research included static and dynamic tests and the calibration of refined finite element models simulating the static loads acting on the structure during the first series of diagnostic tests. The main objective of this study centered on (a) presenting a diagnostic test protocol using robust and reliable measurement devices (including noncontact laser technology) to record the bridge's initial service response; and (b) obtaining the initial spans' performance to evaluate and compare the SCC versus conventional concrete girders' response when subjected to service loads. The initial response of the end spans (similar geometry and target compressive strength, but with girders fabricated using concrete of different rheology) was compared, and no significant difference was observed.
... The dynamic load allowance (DLA) or impact factor has been defined as the ration of the maximum dynamic and static responses regardless of whether the two maximum responses occur simultaneously (Bakht & Pinjarkar, 1989, Deng et al., 2015, Paultre et al., 1992. The experimental DLA for the interior girder 3 of Bridge A7957 was estimated using Equation (3). ...
Chapter
Field tests have been widely adopted to monitor and validate the use of novel construction technologies and to perform an experimental evaluation of existing bridges. The AASHTO Manual for Bridge Evaluation defines two test methodologies: proof load tests and diagnostic load tests. Proof load tests are employed to estimate the maximum safe live load a bridge can withstand without undergoing inelastic deformation. Diagnostic load tests are used to better understand a bridge’s in-service response. Diagnostic load tests have largely proven that existing bridge superstructures possess additional strength capacity than predicted by analytical methods. This difference can be explained by considering some in-situ parameters that are beneficial to the bridge’s performance. This chapter introduces an example diagnostic load test conducted on the superstructure of Bridge A7957, built in Missouri, USA, to illustrate how experimental in-situ parameters can be included in the estimation of a bridge load rating. The experimental load rating resulted to be less conservative than the analytical load rating.
... Table 4 gives the values of calculated superstructure equivalent stiffness (k cup ) and damping (c cup ) for a recommended average damping 5% of critical damping (f ¼ 0.05) for the reinforced concrete bridges (Aviram, Mackie, & Stojadinovi c, 2008). From an experimental study on hundreds of highway bridges, the natural damping was found to be in the ranges from 1.3% to 8.4% of critical damping (Paultre, Chaallal, & Proulx, 1992). To verify the application of superstructure equivalent stiffness and damping elements used in the Model-3, a modified model of Model-3 by considering the superstructure mass at the pier top using an equivalent mass point element named Model-3-m sup is considered. ...
Article
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This paper aims to numerically evaluate the effects of girder bridge superstructure on the impact responses and load paths transferring the shear force of pier subjected to a moderate-energy barge collision in LS-DYNA. First, two multiple-pier systems of St. George Island Bridge in Florida which have different piers in terms of structural characteristics (such as mass and stiffness), geometry, and the height of impact location are considered as the cases of study. From the numerical barge collision simulations, different impact responses and load transferring paths from the impact location to farther zones are observed. In addition, the sensitivity of impact responses, and the impact load paths transferring shear force to the superstructure mass, stiffness, and damping are studied by developing four different models of pier-superstructure interaction and carrying out a parametric study. It is found that the increase in the value of superstructure parameters has positive effects on the impact forces and the internal stresses in the piers. However, the sensitivity of shear stresses generated at various zones of the pier extremely depends on the impact load paths transferring shear force in different piers with different relative characteristics rather than the superstructure.
... To evaluate the impact of dynamic loads on the impact forces imposed on the tire-road contact surface, the dynamic amplification factor was computed. According to [42], a moving vehicle generally generates higher dynamic responses in structures than a static vehicle, a phenomenon referred to as dynamic amplification. Deng et al [43] defined dynamic amplification factor (DAF) as given by Equation (12). ...
Article
Trucks experience excitations during haulage due to road roughness, generating dynamic loads. Current mine haul road design techniques assume static tire loads, ignoring dynamic forces. This paper presents mathematical models for estimating tire dynamic forces on haul roads. Models were solved in Simulink® and RStudio® to generate random road profile (class D) according to ISO 8608, and compute dynamic forces for 59/80R63 tire. Results show that road roughness significantly affects impact forces on roads, with tire dynamic forces (1638.67 kN) ~ 1.6 times static forces (~1025 kN) at rated tire payloads. The method presented gives realistic estimates of tire impact forces, which serves as useful input for haul road design.
... Thus, numerical methods are necessary for more general moving load simulations [10]. Authors [11] present a good historical review of the code based dynamic amplification factors (DAF) caused with travelling loads in the context of road traffic. The DAF represents the increase in quasi-static peak deflections and/or stress caused by the dynamics of the travelling load. ...
Article
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In this paper the dynamics of a set of ultra-high-speed (UHS) moving masses/loads traversing a continuous beam are explored. The proposed model is intended to simulate the dynamic response of continues bridges under the new Hyperloop/Transpod trains, which are proposed to travel at up to 1200km/h. This speed introduces a range of dynamic responses that have hitherto not been observed in generic high-speed trains. The analytical results show that the dynamic amplification factors, due to train passage, are significantly larger than current trains. This is due to the combination of ultra-high-speed and continuous beam construction, which is necessary to maintain a partial vacuum in the enclosed tube. Therefore, current design recommendations are not sufficient for these UHS trains.
... Consequently, all modern measuring technologies for bridge structures can be divided into three groups. The first group includes the use of radar systems of millimeter and optical ranges of electromagnetic waves [10][11][12][13][14][15] for estimation of deformations and deflections of bridge elements, including stay-cables which support the buildings. For this purpose, in particular, phase interferometers with a high-resolution range are used. ...
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In remote measurements on large-sized objects main focus is on measuring deformations of bridge surfaces and determination of the dynamic amplification factor in particular. The proposed method estimates deflections of entire lower surface of a bridge due to placement of secondary radiators on this surface. Antenna array directivity pattern (ADP) is distorted during deflection of the bridge surface. ADP distortions contain the information about deflections of the individual points of the surface. Minimization of the distance in a functional space with a quadratic metric (the functional) between a distorted measured ADP and theoretical one allows us to determine these deflections. The main problem is measurement of the secondary radiators system ADP in far zone which often cannot be achieved for real bridges in practical situations. Therefore, a new method for determining surface deflections based only on field amplitude measurements in near-field zone of a secondary radiators system is considered in the article. This amplitude of field strength depends on the bridge surface deflection. The modulus of difference between the normalized amplitude distribution of the measured field at the outputs of the receiving array elements, which is created by the radiators system of an unloaded bridge, and the similar amplitude field distribution of a loaded bridge is minimized and deflection of the bridge at the points of the radiating elements placement is calculated.
... In order to identify the influence of vibrations on the structure of Forum Gdańsk, the method described in [17] was used. It is based on determining the dynamic coefficient, defined as the ratio of the maximum dynamic displacement to a static deflection. ...
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This paper presents the study of the impact of vibration induced by the movement of the railway rolling stock on the Forum Gdańsk structure. This object is currently under construction and is located over the railway tracks in the vicinity of the Gdańsk Głowny and Gdańsk Środmieście railway stations. The analysis covers the influence of vibrations on the structure itself and on the people within. The in situ measurements on existing parts of the structure allow us to determine environmental excitations used for validation and verification of the derived FEM model. The numerical calculations made the estimates of the vibration amplitudes propagating throughout the whole structure possible.
... Bridges are defined as longitudinal structures that have a span length greater than 12.2 m [9]. For bridges, IM has primarily been seen as a function of road surface roughness and the ratio between a bridge's natural frequency and the natural frequency of the vehicle loading the structure [1,5,10,13,14,16,17]. In addition, it has been recognized that trucks typically oscillate at two dominant frequencies: one between 2 and 5 Hz and another between 10 and 15 Hz [6,8,16]. ...
Article
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It is well established that vehicular traffic traveling over bridge-like structures can impart a dynamic load effect that is greater than vehicles’ static weight alone. In order to account for this increased load, bridge design codes use a factor known as the dynamic load allowance (IM) to amplify static vehicular live loads. In the current version of the American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), reductions in IM are allowed for bridges having span lengths greater than 12.2 m with road surfaces in good condition. In addition, the current AASHTO LRFD Bridge Design Specifications allow for a reduced IM for culverts with higher fill depth. However, many culverts have neither span lengths greater than 12.2 m nor higher fill depths and thus are not eligible for such IM reductions. This paper investigated whether similar IM reductions can be considered for culverts with smaller span lengths and fill depths. The field experiments conducted suggest that culverts having span lengths less than 12.2 m and fill depths less than 0.5 m could be considered for similar IM reductions allowed by the MBE.
... Not many authors have collected data dealing with frequencies of bridges, contrarily to what have happened with buildings [9] or footbridges [10], to name the ones by the first author. Authors such [11][12][13] are a few examples of the experts which made data collection dealing with bridge frequencies. In Fig. 6 we show the classical proposal by [12], respecting to the frequency of a large number of general and railway bridges. ...
Article
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A data-base of 285 bridges in Portugal was composed with information about the geometric characteristics like largest span length, height and cross-section, as well as the main vibration frequencies with special emphasis on the frequency of first vertical mode. This data-base includes different bridge typologies ranging from reinforced concrete (RC) box girders and RC beam bridges, steel girder bridges, steel truss bridges, RC arch and stone bridges, cable-stayed bridges and suspension bridges. Each one of the bridges was subjected to an in situ test with a single 3-component accelerometric station and its main natural frequencies were determined. Very good correlation of the vertical frequency with largest span length was obtained for the first four typologies above referred. Good correlations were obtained for the transversal frequency with the total length of long span cantilever RC bridges. Numerical modelling was performed for six long span cantilever RC bridges and comparison with in situ frequencies in the vertical and transversal directions was made. Further discussion was made on the value of frequency estimation, in view of the uncertainties in methods and analysis, the changes that are observed along the lifetime and the corresponding interpretations. This last point is related to the continuous vibration monitoring of structures which is very important in damage detection.
... This increase is quantified by the dynamic amplification factor (DAF) which is defined 380 as the ratio of the structure response under dynamic loads and static loads. There are several 381 definitions for the DAF but the definition of the DAF adopted in this study can be expressed 382 as follows [38,39]. 383 ...
... Most studies using the analytical approach have been conducted to investigate the bridge-vehicle interaction and estimate the DLF. For example, Paultre et al. [1] presented an extensive review of early studies conducted on bridge dynamics and the evaluation of the dynamic amplification factor (DAF). McLean and Marsh [2] provided a synthesis that summarizes the important knowledge and findings with respect to vehicular dynamic load effects on highway bridges. ...
Article
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Studies on dynamic impact of high-speed trains on long-span bridges are important for the design and evaluation of high-speed railway bridges. The use of the dynamic load factor (DLF) to account for the impact effect has been widely accepted in bridge engineering. Although the field monitoring studies are the most dependable way to study the actual DLF of the bridge, according to previous studies there are few field monitoring data on high-speed railway truss arch bridges. This paper presents an evaluation of DLF based on field monitoring and finite element simulation of Nanjing DaShengGuan Bridge, which is a high-speed railway truss arch bridge with the longest span throughout the world. The DLFs in different members of steel truss arch are measured using monitoring data and simulated using finite element model, respectively. The effects of lane position, number of train carriages, and speed of trains on DLF are further investigated. By using the accumulative probability function of the Generalized Extreme Value Distribution, the probability distribution model of DLF is proposed, based on which the standard value of DLF within 50-year return period is evaluated and compared with different bridge design codes.
... The pedestrian bridge dynamic response analysis is the analysis of the bridge structure under dynamic loading force in the crowd with the position of mobile response, and the response is derived the pedestrian load power factor based on power. Analysis of the deformation process to fully grasp the situation by force bridges and bridge components, direct analysis of the carrying capacity and performance of the structure through the use of dynamic response [4]. ...
... In some cases this response is determined from quasi-static tests where the vehicle traverses the bridge at crawl speeds. In other cases, static response is obtained from measured dynamic response by applying a low-pass filter to isolate the difference between static and dynamic effects [3][4][5]. Irrespective of approach used to define field measured static response, the most common method used to find the IM is based on maximum dynamic and static response in an element as shown in Eq. 1. ...
Conference Paper
Live load performance of a recently constructed, prestressed concrete bridge was investigated to determine the Impact Factors (IMs), the Girder Distribution Factors (GDFs). The bridge was subjected to controlled static and dynamic loading using two Denver Transit Partners (DTP) electric-multiple-unit rail cars prior to a commuter rail line being placed into service. The rail cars travelled along northbound and southbound tracks of the four span, horizontally curved, bridge at various speeds. A total 24 tests were conducted and response was measured using a combination of strain sensors and accelerometers installed at critical sections on the supporting girders. Results for IMs and GDFs obtained from the field tests are presented. These results are also compared against relevant code provisions and these preliminary results indicated that IMs are insensitive to train speed and are smaller than investigated code provisions and that measured GDFs were different than those provided by these code provisions.
... Stress range is a key parameter that affects the fatigue behavior of steel bridges. As illustrated in Fig. 4 , the IM_ SR is defined as follows (Patrick et al. 1992): ...
Article
The purpose of this paper is to evaluate the impact factor (IM) in LRFD bridge design specifications for fatigue design and to propose a method for determining reasonable IMs for the fatigue design of steel I-girder bridges that can more rationally consider the effect of the deterioration of the road surface condition (RSC) during its whole lifecycle. The deterioration process of the RSC was investigated under the given traffic and environmental conditions, and the number of truck passages taken for the RSC to deteriorate from one class to the next was investigated. A three-dimensional coupled vehicle-bridge model was developed to simulate the interaction between the bridge and vehicle, with both the bridge and fatigue load models adopted from an existing LRFD code. The IM of the stress range (IM-SR), which is calculated using the stress range instead of the maximum stress used traditionally, was used for the fatigue analysis of steel girders. Numerical simulations were performed to study the IM-SR of steel I-girder bridges under different RSCs while taking into consideration the effect of two other important parameters: bridge span length and vehicle speed. Results show that the RSC has a greater impact on the IM-SR than on the traditional IM, and the IM-SR is greater than the traditional IM calculated using the maximum stress. By considering the cumulative fatigue damage caused by the passage of each truck under different RSCs and the deterioration process of the RSC during its whole lifecycle, simple and reasonable expressions were proposed for the IMs for fatigue design of steel I-girder bridges under the given traffic and environmental conditions.
... Previous studies (Scheling 1992, Hwang and Nowak 1991, Kwasniewski, Wekezer, Roufa, Li, Ducher and Malachowski 2006, Paultre, Chaallal, and Proulx 1992 have considered the impact of abnormal vehicles in general. The aim of this paper is to investigate the impact of mobile crane on short span bridges and discuss their relevance to the South African abnormal loading codes. ...
Article
This paper presents an experimental study of the impact factors of mobile cranes on short span bridges. Previous studies have looked at the impact factors for abnormal vehicles in general but there has been no focus on mobile cranes which have different suspension system and axle configurations. Field tests were performed on a medium span concrete to measure the dynamic impact caused by a 36 tons mobile crane. A wooden plank was placed across the instrumented beam to model a deteriorated road surface. Field measurements were used to calibrate a finite element model representing the vehicle-bridge interaction. The study has found that the impact caused by the mobile crane is dependent on its speed, suspension system, weight and condition of road surface.
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Prezentowana monografia stanowi podsumowanie wieloletnich doświadczeń Instytutu Badawczego Dróg i Mostów (IBDiM) związanych z wykonywaniem badań konstrukcji mostowych pod próbnym obciążeniem. Pierwsza części monografii zawiera krótki przegląd literatury z uwzględnieniem historii, roli i znaczenia badań konstrukcji mostowych pod próbnym obciążeniem w Polsce i na świecie. W drugiej części monografii zaprezentowano stosowaną w IBDiM metodykę badań obiektów mostowych pod próbnym obciążeniem z podziałem na badania pod obciążeniem statycznym i dynamicznym. W kolejnych częściach – trzeciej i czwartej – przedstawiono przykłady badań pod obciążeniem statycznym i dynamicznym z dodatkowym podziałem na badania odbiorcze i diagnostyczne. Przykłady zostały wybrane spośród 780 badań zrealizowanych od 1996 roku przez zespoły Instytutu Badawczego Dróg i Mostów z Zakładu Mostów z Warszawy i z Ośrodka Badań Mostów z Kielc. Kryteria wyboru uwzględniały specyfikę badań prezentowanych konstrukcji lub wystąpienie nietypowego zachowania konstrukcji podczas obciążenia. Ta część monografii może być dla czytelnika mini bazą zachowania różnego typu konstrukcji mostowych pod obciążeniem statycznym lub dynamicznym. W podsumowaniu przedstawiono główne wnioski z zaprezentowanych badań oraz wizję roli badań pod próbnym obciążeniem w najbliższej przyszłości. Proponowane zmiany podejścia do badań odbiorczych pod próbnym obciążeniem są zgodne z wytycznymi „WR-M-23 Wytyczne wykonywania badań drogowych obiektów mostowych pod próbnym obciążeniem. Wzorce i standardy rekomendowane przez Ministra właściwego ds. transportu”. Należy zaznaczyć, że wprowadzone zmiany, a w szczególności związane ze zmniejszeniem zakresu obligatoryjnie obciążanych konstrukcji, wywołały dyskusję w środowisku jednostek wykonujących badania, w tym również wśród autorów niniejszej monografii. --- The presented monograph is a summary of many years of experience of the Road and Bridge Research Institute (IBDiM) in connection with the testing of bridge structures under test loads. The first part of the monograph contains a short review of the literature, including the history, role and significance of tests of bridge structures under test loads in Poland and globally. The second part of the monograph presents the IBDiM’s methodology of bridge structure load testing, with division into static and dynamic loads. The following parts – the third and fourth – present examples of tests under static and dynamic test load with an additional division into acceptance and diagnostic tests. The examples were selected from among 780 studies carried out since 1996 by teams from the Road and Bridge Research Institute from the Bridge Department in Warsaw and the Bridge Research Centre in Kielce. The selection criteria took into account the specificity of testing the presented structures or the occurrence of unusual behavior of the structure during loading. This part of the monograph may constitute for a reader a mini-basis of the behavior of different types of bridge structures under static or dynamic loading. In conclusion, the main findings of the tests presented and a vision of the role of load testing in the near future are presented. The changes proposed in the approach to acceptance load testing are in accordance with the “WR-M-23 Guidelines for Road Bridge Load Testing. Benchmarks and standards recommended by the Minister responsible for transportation”. It should be noted that the changes implemented, especially those related to the reduction of the range of obligatorily loaded structures, caused a discussion among the testing units, including the authors of this monograph.
Article
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The Dynamic characteristics such as damping ratio and natural frequency are an important indicator for predicting the dynamic behavior of bridges, but it is customary during the design that the designer assess the dynamic properties of the dynamic analysis because it is very difficult to determine the damping of the origin before construction and damping is taken as a predetermined constant value independent of the response amplitude and frequency of the structure. In the dynamic analysis of constructions design some experimental research has been concerned with the determination of dynamic structural properties and their relationship with the response amplitude experimentally, but the changes in dynamic properties with vibration amplitude has never been taken During dynamic analysis, further analytical treatments and computer modeling were required to study different cases based on the experimental results available by simulating them with a computer model. Dynamic characteristics are very essential to accurately determine the dynamic response, and it is necessary to study the effect of changes of the actual dynamic characteristics of bridges, which were determined by measuring their vibration in the results of dynamic analysis and comparing them with results that do not take into account the changes of dynamic properties and with laboratory results in order to assess the role of. Dynamic analysis inputs in simulating vibrations by monitoring their responses. As a result, it was found that the dynamic properties are independent of the shape of the external exactions. Also, it was concluded that relationships express the change of dynamic properties in terms of vibration amplitudes. And Similar reliance of the dynamic characteristics to the vibration amplitude is confirmed for the pier model, where the increase of the amplitude of the acceleration is accompanied by a decrease in the natural frequency, and an increase in the damping ratio is obvious. Before choosing design values when considering the dynamic characteristics of a structure, we need to give unique concentration to the predictable vibration amplitudes. Dynamic characteristics changes during dynamic analysis should be considered to produce analytical results that simulate experimental results and are closer to reality.
Chapter
The chapter contains the durability problem of soil-steel bridges. Experimental tests of road and railway bridges under normal service loads are presented. Displacements, strains, vibration velocities, frequencies, accelerations, vibration damping in soil-steel bridges are analysed in detail. Besides, the dynamic amplification factors are also shown as the one of the most important element for designing the bridges. The load rating procedure of soil-steel bridges is presented. Durability tests of the backfill corrosivity are also described including the soil resistivity testing (Wenner method) and acidity (pH value) and moisture content of backfill. Statistical interrelation between soil resistivity and pH, moisture content was performed. American, Australian and Canadian standards concerning the estimation of soil-steel bridge durability were verified and confronted with the conditions of the minimum durability as for culverts (40 years) and the service life expected as for typical bridges (100 years). At the end of the chapter, the deformation of the ground caused by the traffic live loads is shown including the damping in soil medium. In addition, the mathematic model of soil deformation is also given.
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The current evaluation method of load carrying (LC) capacity of bridges in Korea requires a numerical structural analysis model and a vehicle passing-field test on the bridges. However, in order to reflect the current health state of bridges, the numerical (FE) model has to be built every evaluation time. Also, to conduct the vehicle passing test, no other vehicles are allowed to pass over the bridge during the test, which is inconvenient and causes traffic jam. Furthermore, the peak impact factor should be decided considering all possible vehicle speeds on the bridge. However, practically, it is not possible to conduct the vehicle passing test under all of these vehicle speeds. Therefore, in this study, an alternative evaluation method is proposed, and it basically depends on the fundamental frequency of bridges. Generally, bridge natural frequency tends to decline by time; this reduction of frequency is used as an index to present the current health state of the bridge. Also, the proposed method is based on a frequency-peak impact factor response spectrum which considers all the possible vehicle speeds and fundamental frequency of bridge. This paper explains in details the framework of the proposed method, using a simply-supported beam bridge as an example.
Chapter
Das Befahren einer Brücke ist ein instationärer dynamischer Vorgang, bewegen sich doch die mit Massenträgheit behaft eten Brückenbauteile und Fahrzeuge innerhalb der auft retenden Durchbiegungen auf und ab und ändern letztere fortlaufend ihre Stellung. Insbesondere bei Eisenbahnbrücken, bei denen das Verhältnis der Belastung zum Eigengewicht der Brücke hoch ist, kann dies zu erheblichen dynamischen Zusatzbeanspruchungen führen. Dies ist bereits seit den Anfängen des Eisenbahnbrückenbaus in der Mitte des 19.
Article
Nowadays, finite element analyses provide information about the performance of a structure, but they are more or less simplified. Therefore, load tests are the only way to find the “real” behavior of an existing bridge subjected to the rating process. In this paper, the state-of-the-art concerning load tests of concrete road bridges is presented, and the problems of the execution of such tests are specified. It is pointed out that only load tests accompanied with current finite element analyses may result in a proper assessment of the level of safety of the bridge. The authors’ procedure of complex assessment of such bridges combines in-situ examination of the structure, load testing, and finite element modeling. The paper discusses the following topics: • Aims and fundamentals of static diagnostic and proof load tests, • The load application method according to different codes and specifications, • The basis for proper assessment of the target load: reliability index, partial factors approach, global rating factor approach, • Establishing the load allowable on the bridge, based on the applied proof load, • The proposed procedure of assessment of existing concrete road bridges by load testing.
Article
A large subset of the Dutch bridge stock consists of reinforced concrete slab bridges, for which assessment often results in low ratings. To prioritize the efforts of the bridge owner, more suitable assessment methods for slab bridges are necessary. Research efforts over the past years resulted in the development of several methods, at levels requiring increasing costs, time, and effort for increasing accuracy. The last option, when an analytical assessment is not possible due to uncertainties, is to use proof load testing to evaluate the bridge directly. To develop recommendations for the proof load testing of reinforced concrete slab bridges for the Netherlands, different methods are combined: pilot proof load tests on bridges with and without material damage, a collapse test, tests on beams taken from an existing bridge and new beams with similar dimensions cast in the laboratory, and an extensive literature review. The result of this study is a set of recommendations that describe how to prepare and execute a proof load test, and how to analyze the results. This paper summarizes the research program about proof load testing from the Netherlands and gives an overview of the currently developed recommendations and topics for further research.
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Over the years, there have been numerous efforts by researchers in quantifying structural performance and damage from vibration measurements. Curves proposed by several authors try to relate acceleration spectrums to damage level, which were determined based on experimental surveys conducted on buildings. The present work investigates a vibration based criteria for bridge structures as a basis of damage and performance evaluation in existing bridges and also as a way to predict long-term performance during the initial design stage. To achieve this, a database of Brazilian bridges was analysed, whose structural design and dynamic parameters are known. For damage evaluation, a damage index based on dynamic property variation and the general structural condition, observed during detailed inspections, were taken into account. Measured vibration was subsequently assessed against the damage index and an additional reliability index to fatigue, which resulted in a clear correlation between bridge vibration and the indices. As a final result, from the observed correlations, limits of acceleration are proposed to be considered in existing and newly designed bridges to certify an acceptable long-term condition and safety against fatigue effects. A critical assessment of current Brazilian Standard (NBR-15307 2005), which estimates damage as a function of bridge vibration, was also conducted.
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The paper presents selected aspects of dynamic numerical simulations of an orthotropic steel railway bridge loaded by high-speed trains. The model of moving loads was adopted in accordance with the models set out in the applicable standards. The current European code requirements are referred in which the computer calculations of the dynamic response of the structure are the basis for assessing the suitability of the structure to carry high-speed rail traffic (v > 160 km/h). In this research the calculations are based on the author’s method of generating traffic loads in Abaqus FEM environment. It is emphasized in the paper that in most commercial FEM codes (including Abaqus), moving loads are not implemented in modules responsible for defining of loads. The author’s approach to this issue allowed to obtain results confirming its adequacy. In the longer term, the authors will develop a plan to adapt this algorithm in order to generate traffic loads on bridges discretized as spatial and plane numerical models.
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This papers presents a structural assessment of a temporary bridge so called steel modular Fly Over Bridge, by using loading test with static and dynamic schemes. Static test was performed by imposing the bridge using multi axle vehicle with variation of payload start from 240 tons until 300 tons. From static test, it is found that under maximum load condition, the bridge still behave linearly. The maximum stress at the bottom side is still also under the allowable steel stress. There is a residual deflection of approximately 71 mm at mid span because of contraction of the modular segment or insertion link in the connection. Evaluation of dynamic load test shows that from the history of deflection under moving truck, the average Dynamic Load Allowance (DLA) is 1.03 and still complying with the design requirements. Something important to be considered is to make a transverse connection between each side of the segment so that the bridge deformation will occur as in an integrated structure.
Dynamic testing of Milnikek Bridge Department of Civil Engineering, Faculty of Applied Sciences Second series of dynamic testing of Milnikek Bridge
  • P Paultre
  • J Proulx
  • L Thibodeau
  • J Proulx
  • D Hcbert
  • P Paultre
Paultre, P., Proulx, J., and Thibodeau, L. 1992. Dynamic testing of Milnikek Bridge. Research Report SMS-92/01, Department of Civil Engineering, Faculty of Applied Sciences, Universitk de Sherbrooke, Sherbrooke, Que. (In French.) Proulx, J., HCbert, D., and Paultre, P. 1992a. Second series of dynamic testing of Milnikek Bridge. Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, Quebec, Que., May 27-29, Vol. IV, pp. 315-325.
Evaluation of the dynamic properties of a steel arch bridge February 3-7. di is cuss ion by Mark F. Green): this issue
  • J Proulx
  • D Hebert
  • P Paultre
Proulx, J., Hebert, D., and Paultre, P. 19926. Evaluation of the dynamic properties of a steel arch bridge. Proceedings of the Tenth International Modal Analysis Conference, San Diego, Calif., February 3-7. di is cuss ion by Mark F. Green. Canadian Journal of Civil Engineering, 20(5): this issue. Pr~ntcd In Canada / lmprimc au Canada Can. J. Civ. Eng. Downloaded from www.nrcresearchpress.com by Huazhong University of Science and Technology on 06/06/13 For personal use only.