The Open Civil Engineering Journal

Published by Bentham Open
Online ISSN: 1874-1495
Publications
Scheme of coupled multi-scale framework 
Periodic boundary conditions 
Article
The paper reviews several topics associated with the homogenization of transport processed in historical masonry structures. Since these often experience an irregular or random pattern, we open the subject by summarizing essential steps in the formulation of a suitable computational model in the form of Statistically Equivalent Periodic Unit Cell (SEPUC). Accepting SEPUC as a reliable representative volume element is supported by application of the Fast Fourier Transform to both the SEPUC and large binary sample of real masonry in search for effective thermal conductivities limited here to a steady state heat conduction problem. Fully coupled non-stationary heat and moisture transport is addressed next in the framework of two-scale first-order homogenization approach with emphases on the application of boundary and initial conditions on the meso-scale.
 
Article
Wind, wave and current interactions control the boundary fluxes, momentum and energy exchange between the atmosphere and the ocean, and within the water column. The wind wave effect on the circulation is investigated in a three-dimensional time-dependant ocean circulation model. This POM (Princeton Ocean Model) based model is implemented with realistic coastlines in South China Sea and emphasizes the simulation of physical parameters in the water column. Taking account of the wind waves, an increase in air-sea drag coefficient, reflecting an enhanced sea surface roughness due to increased wave heights, is shown to improve the simulated surface current and the sea surface elevation. It is also found that developing waves with smaller peak periods influenced the surface circulation more significantly. The inclusion of the wind wave parameterization also affects the current near the seabed in the shallow water. The model is validated against current, temperature and salinity data measured in the Asian Seas International Acoustics Experiment (ASIAEX). The simulation results in the period of April - May 2001 show that wave-induced surface stress increases the magnitude of currents both at the surface and near the seabed. On the other hand, wave-induced bottom stress retards the near bottom currents in shallow water. Therefore the net effect of wind waves on circulation depends on the significance of current and elevation changes due to wind waves through both the surface and the bottom. Yes Yes
 
Article
The present Special Issue of The Open Civil Engineering Journal collects a selection of extended, reviewed and revised papers presented at the 1st FIMM French-Italian Meeting on Masonry, held in Marseille, France, from 24 to 25 October 2013. The organizers of the meeting were Prof. F. Lebon, Université d'Aix-Marseille Laboratoire de Mécanique et d'Acoustique (FR), and Prof E. Sacco, Università di Cassino e del Lazio Meridionale (IT). The main aim was to exchange new ideas and show the state of the art of different research groups active in France and Italy, two countries at the top of the world for the research on masonry. Universities involved were: Université d'Aix-Marseille (FR), Université de Montpellier 2 (FR), Université de Limoges (FR), Politecnico di Milano (IT), Università di Roma la Sapienza (IT), Università di Ferrara (IT), Università di Cassino e del Lazio Meridionale (IT). A Scopus enquire with keyword “masonry” ordered by country shows 1609 records for Italy and 274 for France, with a percentage contribution respectively of 12.5% and 2.1% on the global scientific production, putting thus in evidence the importance of a tight interaction between French and Italian research groups. After the success of the first edition, the 2nd FIMM French-Italian Meeting on Masonry, will take place in Milan, Italy, from 30 to 31 October 2014. The special issue collects three papers. Fouchal et al. [1] present an evolution of the interface model originally presented by Rekik and Lebon, including cracks and roughness, with a comparison with experimental data on specimens subjected to shear tests. In the second paper, Tralli et al. [2] report a comprehensive state of the art on the cutting edge numerical research devoted to masonry vaults. Finally, Addessi et al. [3] review some advanced homogenization, micro- and macro-modelling strategies suitable for the analysis of masonry in the inelastic range. I wish to thank all the authors for their valuable contributions. All manuscripts underwent technical peer review. I therefore also wish to thank all the reviewers for their critical comments which undoubtedly improved the original technical value of all contributions.
 
Article
Background Seismic risk mitigation has become a crucial issue due to the great number of casualties and large economic losses registered after recent earthquakes. In particular, unreinforced masonry constructions built before modern seismic codes, common in Italy and in other seismic-prone areas, are characterized by great vulnerability. In order to implement mitigation policies, analytical tools are necessary to generate scenario simulations. Methods Therefore, data collected during inspections after the 2009 L’Aquila, Italy earthquake are used to derive novel fragility functions. Compared to previous studies, data are interpreted accounting for the presence of buildings not inspected due to those being undamaged. An innovative building damage state is proposed and is based on the response of different structural elements recorded in the survey form: vertical structures, horizontal structures, stairs, roof, and partition walls. In the suggested formulation, the combination of their performance is weighted based on typical reparation techniques and on the relative size of the structural elements, estimated from a database of complete geometrical surveys developed specifically for this study. Moreover, the proposed building damage state estimates earthquake-related damage by removing the preexisting damage reported in the inspection form. Results Lognormal fragility curves, in terms of building damage state grade as a function of typological classes and peak ground acceleration, derived maximizing their likelihood and their merits compared with previous studies are highlighted. Conclusion The correction of the database to account for uninspected buildings delivers curves that are less “stiff” and reach the median for lower peak ground acceleration values. The building feature that influences most the fragility is the masonry quality.
 
Design versus Demand, Elaborated by Maria Cristina Avalos (Based on New Zealand Department of Building and Housing, 2012). In the case of the CTV Building after the Darfield Earthquake the columns presented cracks due to the non-ductile reinforcement distribution. It was less than the minimum required reinforcement for shear in circular columns. Additionally, large portions of concrete cover, low concrete compression strengths critical columns, and lack of ductility in the beam-columns joints, which provoke fragile columns, were reported. The forces and displacements produced during the 6.3 Mw earthquake affected the critical columns and made them overloaded. Consequently, it provoked failure on the contiguous slabs [5].  
Alto Rio Condominium irregularity [14].  
Tension Compression Failure in Central Park Building [16].  
Article
Previous works on the earthquakes of Chile 2010 and New Zealand 2011 indicate regular behavior of reinforced concrete buildings with structural walls. However, some buildings suffered significant damage associated with global or local collapse due to diagonal cracking and flexural-compression failure. Structural walls located at the ground floor presented tension-compression failure was probably provoked by high axial forces at the walls extreme ends which could cause this failure in places where there is a lack of bracing and confinement. The purpose of this paper is to analyze the behavior of the reinforced concrete structural wall buildings that failed in the mentioned earthquakes, and identify some of the main reasons that caused the damage as an attempt to improve engineering practices in Ecuador to prevent catastrophic events.
 
Article
Introduction The recent wave of seismic shocks in Central Italy (2016) had once more disastrous consequences for the local monuments, which consisted of old masonry churches and towers. The permanent, seismic-induced damage to cultural heritage has become a serious issue that can no longer be downsized, and questions have been raised about how to satisfactorily assess the vulnerability of such heritage in advance. This paper deals with the investigations into the actual condition of a historic city center partially destroyed by the seismic sequence occurred in May 2012 in Emilia-Romagna. Namely, the case of Finale Emilia – a small to medium-sized village located at the very center of the stricken area – is considered. Methods Three important heritage masterpieces were numerically analyzed using Finite Element meshes to deepen the knowledge of their seismic vulnerability and try to avoid similar disasters in the future. The first structure is a masonry castle known as “Castello delle Rocche”, which underwent severe damages during the seismic sequence. The second and third examples deal with the structural analysis of two towers, both collapsed due to the quakes: the Fortified Tower of the castle and the Clock Tower of the village. The last analysis is devoted to study the seismic behavior of a medium-sized masonry church (Santa Maria del Rosario), heavily damaged by the seismic sequence and whose bell tower collapsed due to the formation of a hinge at mid-height. Results and Conclusion Numerical models were created for all the buildings involved, and a variety of advanced analyses were carried out, including nonlinear static and dynamic ones, to have a deep insight into their expected vulnerability, also finding reasonable correspondence between the numerical results and the actual state of damage observed during the surveys made in the aftermath of the seismic events.
 
Final migration sections. 
A simple geology model of survey area. 
Synthetic data of geology model. 
Standard time section of survey area. 
Article
By summarizing the experiences of routine acquisition geometry designs, and using the 3D seismic survey data of a less explored region for instance, this paper put forward an acquisition geometry design method for less explored region plus the geological stratum calibration by reflection wave and time-depth conversion method. After drilling data and roadway data verification, the re-argumentation of acquisition geometry parameters for parameter determination and the forward modeling technique for geological stratum calibration and the stacking velocity time-depth conversion are proved to be very effective in improving the accuracy of seismic survey.
 
Article
Caving zone and fractured zone both appear in the Changzhi Basin in China as the a large number of coal are mined from the area. Based on ore cluster mining and on GIS (Geographic Information System) technology, in the paper, it combines the 3-D (three dimensional) simulation technology and adopts the spacial interpolation method to develop the 3-D stratigraphic model of the studied region, the 3D stratigraphic model and the division idea which is applicable for the study region are obtained. The virtual drilling technology is applied to obtain precise stratigraphic data and calculate the heights of the caving zone and fractured zone of Changzhi Basin, their relative locations to the overlying aquifer and the water-flowing fractured region of influence based on computer-simulated data are both analyzed. In addition, it also puts forward the concept of effective water-flowing fractured rate, which lays a solid foundation for further study on the heterogeneous evolution of the spatial structure of regional aquifers after the coal mining which also can provide a data support for future studies on the heterogeneous evolution features of water-bearing media.
 
Article
Conventional fictitious stress methods (FSM) employ numerical integration to calculate displacements or stresses on each element unit. The paper represents a kind of three-dimensional fictitious stress method adopting analytical integrals over triangular leaf elements instead of numerical integration and presents how to analyze stress and displacement of surrounding rock around roadway by the 3D-FSM. The results computed by it are compared with the results by Flac3d, which proves that it is a correct and rational method to solve three-dimensional mechanics problems especially about hole and crack in an elastic body.
 
Article
The Maniace Castle in Syracuse, Italy, built under Emperor Frederick II in the first half of the 13th century, is analyzed from a structural point of view by means of a detailed 3D Finite Element model. The castle was struck by many catastrophic events during the centuries, which heavily damaged the structure and caused subsequent changes in the origi-nal implant. After a concise description of the main architectural characteristics of the building and its actual state of degradation, two full 3D FE numerical analyses are discussed, representing respectively the present geometric configuration and that ob-tained after a hypothetical intervention aimed at reporting the structure into its original conceived shape. Conventional static analyses in the linear range are performed on such large scale meshes, under gravity loads and horizontal loads con-ventionally representing seismic excitation, respectively investigating the role played by self-weight into the degradation of some structural elements (particularly central columns of the hypostyle hall) and the effect induced by horizontal forces on both the global behavior and the local widespread local regions with positive stresses. On the basis of such numerical results, some useful observations to be considered in a future plan of restoration aimed at reporting the castle in its origi-nal configuration are finally provided.
 
Article
Due to the complexity of multiple rocks and multiple parameters circumstance, various parameters are often reduced to only one parameter empirically to generalize geological conditions, ignoring the really influential parameters. A developed method was presented as a complement to 3D displacement inversion to obtain the relative important parameters under complex conditions with limited computational work. Furthermore, this method was applied to a high steep slope in open-pit mining to investigate field applicability of the developed system. Back analysis was conducted in the reality of the east open-pit working area of Daye Iron Mine and propositional steps were presented for parameters solving in complex circumstance. Firstly, multi-factor and single-factor sensitivity analysis were carried out to classify rock mass and mechanical parameters respectively according to the extent of their effects on deformations. Secondly, based on the results, main influence factors were selected as inversion parameters and taken into a 3D calculating model to get the displacement field and stress field, all of which would be the artificial network training samples together with inversion parameters. Thirdly, taking the real deformations as input for the trained back propagation (BP) neural network, the real material mechanical parameters could be obtained. Finally, the results of trained neural network have been confirmed by field monitoring data and provide a reference to obtain the matter parameters in complicated environment for other similar projects.
 
Cloud model.  
Qualitative Rule Generator (single condition and single rule).  
Article
Based on the analysis of the classification criteria from various factors,a comprehensive evaluation system of the erosion stability of the vegetated eco-slope protected by 3D geomat is established. To solve the problem of uncertainty in the slope erosion stability analysis and consider the feature of both of random and fuzziness, the theory of Cloud Model has been applied into comprehensive evaluation to realize the uncertainty conversion between the qualitative concept and the quantitative data. By constructing the qualitative rule generator, the specific score of the evaluation index is determined according to the uncertain reasoning. The weights of the evaluation indexes are determined with the help of the Analytic Hierarchy Process developed by Cloud Model (CM-AHP), and then the overall score of the comprehensive evaluation system is obtained. The results of engineering examples demonstrate the practicability and effectiveness of the assessment model, which provides a new way for the evaluation of the erosion stability of the vegetated eco-slope protected by the 3D geomat.
 
Article
Slope protection with 3D geonet is an economic, convenient and eco-friendly technique; and it is increasingly used in practical projects. However, 3D geonet is sensitive to the ambient environment; and it might lose its stability due to rainfall infiltration. In this paper, the overall instability failure of the 3D geonet system under rainfall infiltration is analyzed. By adopting the limit equilibrium method, a slope stability analysis model is established; and the influence of slope angle, rivet space, slope length, rainfall intensity on stability are analyzed, and a formula for calculation of design optimization of rivet space is obtained. The research result would provide technical support for the design and stability analysis of slope protection with 3D geonet.
 
Article
Wetlands are important to the survival of the earth environment and ecosystems, along with the extent of the ecological study of regional governance continues to accelerate, the regulators have implemented various ecological management project management process kinds of data and information related to the increasing range. The traditional data management model is difficult to meet the current needs of engineering data management; On the other hand, the study area of wetland ecological management is a very large and complex systems engineering, the development of ecological planning for the study area, researchers need to master the ecological evolution and resource development data for the study area have a comprehensive understanding of the historical evolution. Therefore, the establishment of research and development based on 3S technology which research regional ecological engineering design data management needs of ecological engineering database is very important for the planning of the regional ecological engineering, management, decision-making, assessment, analysis and dynamic monitoring to provide technical support to achieve the dynamic management of ecological engineering, comparative study of regional environmental and ecological data at different times to seek more rational governance.
 
Article
The performance of resisting foundation displacement of typical single return circuit and double return circuit transmission towers under all kinds of load conditions including foundation horizontal displacement, foundation vertical uneven downward displacement were analyzed by finite element modeling. Results showed that stability failure of single steel angle represents tower's limit state under foundation displacement. The corresponding foundation displacement limits were calculated. And the towers' reliability were assessed by comparing the calculated earth surface deformation in advance to the towers' earth surface deformation permissibility. Result indicates that tower does not fail when foundation displacements are smaller than 0.5% of tower root distance. The assessment result revealed that under coal mining deformation conditions, complex foundation and measures adjusting the length of bolts between towers' legs and foundations can ensure all object towers' safety. The complex foundation is more effective than single foundation in resisting coal mining deformation.
 
Stress-strain curves under shear and compressive loading.  
Tensile stress-strain curves in principal direction.  
Compressive stress-strain curves in principal direction.  
Article
In order to solve the convergence problem of concrete constitutive in the softening phase, an anisotropic nonlinear elastic constitutive model (ANECM) was proposed, which was developed based on the uniaxial concrete constitutive relation in the Chinese code for design of concrete structures (GB 50010-2010). The user material subroutine (UMAT) based on ANECM is developed in ABAQUS software. The above UMAT is applied to analyze a simulation model in ABAQUS software. The result shows that compared to the default plastic-damage concrete constitutive in ABAQUS, ANECM is an effective and appropriate model to simulate the performance of concrete and it has improved the convergence problem.
 
Article
Introduction Reliability analysis is a good tool to deal with the uncertainty and has been widely used in the engineering system. The first order reliability method (FORM) is generally used to calculate the reliability index but FORM is time-consuming and requires derivative computing. Methods Artificial Bee Colony (ABC) algorithm is a very simple, robust and population-based stochastic optimization algorithm. In this study, an ABC-based reliability analysis was proposed to calculate the reliability index of engineering system through combining Artificial Bee Colony (ABC) algorithm with FORM. FORM was adopted to calculate the reliability index and design point. ABC is used to solve the constrained optimization about FORM. The procedure of ABC-based reliability analysis was presented in detail. Results and Conclusion The proposed method was verified by two classic examples and then applied to geotechnical engineering. The results show that the ABC algorithm can effectively solve the global optimization problem in FORM. Results demonstrate that ABC-based reliability analysis is a good approach to obtain the reliability index and design point with a good accuracy so that it can be applied to analyze the reliability of a complex engineering system.
 
Article
To investigate the energy absorption characteristics and crush behavior of layered aluminum honeycomb, the experiments of layered aluminum honeycomb structure under quasi-static load had been carried out, mainly includes single, double, triple, four layer combinations. The results showed that: the peak force and the mean plateau force of single-layer aluminum honeycomb structure are proportional to the surface density, however they decline slightly with increase of the height; unequal height double layered aluminum honeycomb structure has more advantage in cushion performance; with the increase of layers, the MP ratio will decrease; the combination of placing soft layer between hard layers is better than the others.
 
Article
Introduction Bridge scour is one of the major causes of bridge failure. Prediction of the maximum depth and shape of local scour plays an important role in bridge design and maintenance. In this paper, k-ε turbulent model combined with wall function was employed and complex flow fields are exhibited. The bed load transport model summarized by Qian and Wan [1] was applied to evaluate the development of local scour. Besides, σ-grid module was developed and embedded into the commercial solver FLUENT to fit the change of channel-bed. Method In this module, the change of the elevation of the channel bed is calculated through using user defined functions(UDF), and the motion of the grid system is realized based on a program developed through C++ language, which extends the applications of FLUENT. The evolution of local scour hole for two cases, i.e. , local scour around a cylindrical pier and a semicircular abutment, was simulated. Results and Conclusion The depth and the shape of local scour as well as the flow fields were predicted. Numerical result conforms well to the experimental measurement. Especially, it provides fairly reasonable prediction on the key issue of the maximum scour depth. The satisfactory agreement validates the numerical method developed in the present study. In addition to the validation purpose, the different performance of this method for predicting local scour around the cylindrical pier and the semicircular abutment was discussed.
 
Comparisons of strong motion intensities obtained with the four different definitions of duration for the accelerograms in the data base, a) Ism-McS vs Ism-VL, b) Ism-B vs Ism-VL, c) Ism-TB vs Ism-B, d) Ism-TB vs Ism-VL, e) Ism-TB vs Ism-McS, f) Ism-McS vs Ism-B.
Plot of duration in seconds with distance for magnitude range of 5<M<5.9 and the four definitions of duration, a) VL, b) B, c) TB and d) McS.
Plot of duration with distance for magnitude range of 7<M<7.7 and the four definitions of duration, a) VL, b) B, c) TB and d) McS.
Article
Variation of strong motion intensity, root mean square of ground acceleration and time-duration in seconds obtained from 83 accelerograms of 18 earthquakes with magnitudes between 5 to 7.7 were investigated considering four definitions of strong section of accelerograms given by Vanmarcke-Lai; Bolt, Trifunac-Brady and McCaan-Shah. Strong motion intensities were calculated for all definitions of strong duration. Even though, durations in seconds and root mean square of ground acceleration values resulted quite different among the four definitions of strong sections, both durations in seconds and root mean square of acceleration squared values tend to compensate each other to yield the same strong motion intensity for each definition used. Q-ratio as defined by Vanmarcke-Lai (Peak Ground Acceleration divided by root mean square of acceleration) was found not constant but instead it varied significantly for all strong motion definitions. Similarly, ratio of strong motion intensity over peak ground acceleration squared as defined by Vanmarcke-Lai holds linear for time durations less than 20-30 seconds for all definitions, afterwards it shows large dispersion. Finally, Vanmarcke-Lai time duration in seconds appears to increase from near field distance up to a certain medium distance after which it starts to decrease.
 
Article
Background Testing standards prescribe dog-bone samples for the determination of clear-wood longitudinal tensile strength. However, the literature reports a high number of invalid tests due to the unexpected failure of the sample outside the gauge length. Motivation The paper aims at understanding the reason for the premature failure of dog-bone samples and suggesting possible strategies for improving testing protocols. Methods The paper starts with a comparative review of standards for different orthotropic materials. Thereafter, it analyzes the stress distribution in a clear-wood dog-bone sample using a recently proposed stress-recovery procedure and Finite Elements. Finally, the sample failure is considered applying Tsai-Wu and SIA criteria. Results Comparative review highlights the controversy on the choice of the sample geometry. Both analytical and numerical results confirm the presence of shear and transversal stresses in necking regions, overlapping with axial stress greater (up to 2%) than the one in the gauge region. As a consequence, clear-wood dog-bone samples fail not due to a pure axial stress state in the gauge region (as expected), but due to complex stress state in necking region, where failure index is 4 ~ 5% greater than the one in gauge region. Conclusion Assuming that dog-bone samples fail in the gauge region due to pure axial stress is simplistic, as demonstrated by analytical and numerical evidence. As a consequence, interpretations of experimental results based on this belief are misleading and testing protocols should be refined. Indeed, the presence of spurious stresses interfering with expected pure axial stress seems unavoidable. Therefore, clear-wood testing standards should allow to use prismatic samples or, alternatively, to consider as valid also tests on samples breaking outside the gauge region. Both the proposed solutions apparently reduce the accuracy of the experiments, while in contrast, they provide the best achievable results, speeding up the testing procedure and reducing the testing costs.
 
The main scene of the accident. 
Collapse of super-heater tube chamber. 
Tearing seam between the attachment weld. 
Article
By means of on-siteinvestigation, inspection,interior experiments, theoreticalanalysis and calculation, a detailed analysisis carried out on the causeof the partialcollapse accident about a waste-heat boiler steel structure in a cement plant of Hunan province of China. The resultsof inspectionand analysis show that: as a key part of load transfer, the connection weld of long thin steel plate is poor in quality, meanwhile, the detail of beam-column connection can not meet the requirement of rigid joint stipulated by the design, which are the main causes for the collapse accident of boiler steel structure. Based on the analysis of accident cause, some problems worthy of consideration are put forward to the design and constructionof this kind of structure, such asthe weld procedure and quality control of long thin steel plate connection weld, etc.
 
Environment overview of the analyzed area.  
River stretches with excessive pollutants after 90 min in low-flow, medium-flow or high-flow seasons.  
Affected areas after 30/60/90 min in medium-flow season.  
Affected areas after 30/60/90 min in high-flow season.  
Area of regions with excessive pollutants under different conditions.  
Article
Oil pipeline leakages often bring catastrophic impacts on rivers along the pipeline, drinking water sources, and farm land irrigation etc. Based on the distinct spatial-temporal attributes in the analysis of oil spill, diffusion and consequences thereof, we present the theoretical concept and reasoning for leakage accidents spatial analysis through combining GIS and accident aftermath model. Specifically, we aim to achieve quantitative analysis and visualization of oil spill accidents through several GIS functions, which include buffer analysis, overlay analysis, spatial statistical analysis and visualized analysis. Taking a specific leakage accident of oil pipeline river-crossing section as an example, we have analyzed the polluted areas under different diffusion time and the hydrological conditions. In addition, we have evaluated populations and farm land areas affected in terms of drinking water and irrigation as well as their spatial distributions. The results demonstrate that our method can achieve quantitative analysis and visualized representations of oil spills to support policy-makers in making contingency plans.
 
Classification of the respondents according to their experience.
Summary of priority weights of category and sub-category of (66) interviewers' data.
Relevant scores of the factors.
Article
Background The accuracy of the cost estimate is a key success factor for any construction project. It is the base for an effective tendering process. It can also be considered as the cornerstone of the cost control process. Objective This paper aims to develop a model that can be used to assess the expected cost estimating accuracy of construction projects. This model is named as Construction Cost Estimate Accuracy Index (CCEAI). Methods A questionnaire survey that contains fifteen factors clustered into four categories was carried out among 90 experts based on the construction cost estimate. Only sixty-six questionnaires were returned. The Analytical Hierarchy Process (AHP) was used to identify the relative weights of the different cost estimates. Results The questionnaire results were analyzed using the AHP technique to calculate the relative weight for each of the input factors and categories. A Construction Cost Estimating Accuracy Assessment model (CCEAI) was developed based on the calculated relative weights. Then, three projects were used as case study applications to check the validity of the proposed model. The results showed that the CCEAI model is greatly reliable in predicting the expected accuracy of the cost estimate. Conclusion The results of this research and the developed model are very important and can be considered as a powerful tool to predict and improve the expected accuracy of any future construction cost estimate.
 
Article
Background At the early phase of project development, highway engineering estimators seek to determine the duration of highway construction projects for the purpose of construction planning and administration. Thus, it is vital to study and analyze the estimation accuracy factors of highway construction project duration. In this regard, several studies have been conducted to identify and analyze the estimation accuracy factors of project duration in various ways to improve the estimation and management performance of all the contracting parties. However, very less effort has been devoted to evaluating the duration estimation accuracy factors in the case of the highway construction industry under fuzzy environment. Objective This paper aims to analyze and prioritize the critical factors that potentially affect the duration estimation accuracy of the highway construction projects in Ethiopia under fuzzy environment. Methods An extensive review and discussions with highway engineering experts were carried out to explore and identify the duration estimation accuracy factors. The study data collection process consists of two stages. The first stage is to conduct a questionnaire survey. Whereas, the second stage is to carry out the pair-wise comparison matrix to capture the imprecision and vagueness in subjective responses. Then, a λ-cut set method to reduce the initial list of factors and exploratory factor analysis was used to classify the reduced set of factors into smaller groups. Finally, a fuzzy hierarchy process algorithm with the use of triangular fuzzy numbers was presented for prioritizing critical factors. Results A cut -off value, λ = 0.95, was verified which resulted in the identification of critical accuracy factors. Accordingly, 12 critical factors were opted and categorized as a cluster of similar items into 5 groups. Finally, the analytical results obtained from fuzzy AHP algorithm revealed that project complexity, project size, bridge type and complexity were found to be the four top-ranked factors based on the global priority weight. Conclusion These factors must be a serious concern in estimating and administering the contract and the duration of highway construction projects at the early phases of project development so that the time de via tion upon the completion of the project can be minimized.
 
Performance scheme of the bleeding test.
Scheme of the moisture adsorption test of the pipes.
Dependency of thrust from the percentage of fatty acids and pipe jacking speed.
Contact surface of the simulated pipe (optional image).
Article
Background The demand for underground space utilization using pipe jacking method is increased especially in the congested urban area. Methods In the method, the over-cutting area is formed between pipes and surrounding soils in order to smoothly construct underground pipelines. The backfilling materials as a lubricant are injected into the over-cutting area during the constructions in order to reduce the friction resistance and to sustain the surrounding ground against the overburden pressure. Therefore, the performance of lubrication for backfilling material is significant. In this study, the fatty acids are added into the backfilling material to improve the lubrication performance. Conclusion Laboratory studies have shown that the bleeding rate is reduced with the increase in addition ratio of fatty acids, however, the excess addition may cause the shrinkage of the backfilling material due to the effect of water absorption from the pipe. Additionally, 3% addition of fatty acids into the conventional backfilling material is the most effective to reduce the thrust for pipe jacking based on the results of the direct shear tests.
 
Article
The mechanical characteristics of rock salt have an important influence on the safety of the salt cavity. The acoustic emission (AE) technique was used to analyze the generation of microcracks in rock salt under uniaxial compression condition. By monitoring acoustic emission in whole process of stress - strain curve under uniaxial compression test, the damage characteristic of rock salt is obtained. The AE rate-strain curve is able to reflect the damage development process with better consistency evident with the cracks generating. The failure form of rock salt is mainly the shear failure under condition of low loading strain rate. After shear failure, a lot of small crushed particles spread on the surface of the failure surface. A damage constitutive model of rock salt is determined on the basis of acoustic emission characteristics, which could reflect the strength and deformation characteristics before the peak strength.
 
Article
The wind turbine foundation serves as a permanent construction in the harsh marine corrosive environment, its anticorrosion design is essential to the safe use of the wind turbine structure. At present, there is a significant controversy over the local corrosion mechanism (such as pitting corrosion, and crevice corrosion) and its diffusion mechanism in the academic circle. In the paper, the Faraday electrochemistry formula was used to compute the local corrosion degree of the steel pipe pile for the wind turbine and obtain the general corrosion equivalent. The local corrosion effect of the offshore steel pipe pile for the wind turbine was converted into homogeneous corrosion thickness loss of certain length, and then the ultimate strength of the offshore steel pipe pile foundation for the wind turbine was analyzed under the conditions of local corrosion. The result indicates that the maximum ultimate strength reductionof the steel pipe pile for the wind turbine induced by the local corrosion in the splash zone is 80.8% of the noncorrosive ultimate strength. The maximum ultimate strength reduction of the steel pipe pile for the wind turbine induced by the local corrosion in the continuous immersion zone is 63% of the non-corrosive ultimate strength. Once the local corrosion rate in the splash zone exceeds 10%, the ultimate strength of the steel pipe pile for the wind turbine will exhibit a negative exponential decrease. The local corrosion in the continuous immersion zone has a huge effect on its ultimate strength. There are no significant signs of the structural strength loss. The areas prone to local corrosion should be prioritized in anti-corrosion design of the steel pipe pile for the wind turbine.
 
Article
Introduction: In this study, the acceleration time-history curve of blasting vibration is obtained at different explosion distances in different amount of explosion with MATLAB analysis software to determine the dynamic response of mining blasting vibration to surrounding reinforced concrete (RC) frame structures. Objective: Moreover, this paper discusses the dynamic response of two RC structures with different numbers of stories that happen to blasting vibration waves generated by using different amount of explosion at different blasting distances. Result: Results show that the vibration response of the RC frame structures may be larger under the action of blasting vibration. The smaller the explosion source distance, the lower is the structure, and the larger is the story drift, that is, in general, with the same explosion charge and small explosion source, the deformation of lower structure is larger than the higher. The larger the explosion source distance, the smaller is the change range of floor displacement. A larger distance results in a weaker blasting vibration response. Conclusion: Furthermore, the acceleration amplitudes of the top stories are almost equal in both structures with the same amount of explosion and the same explosion distance. It is suggested that the higher the structure, the greater is the influence of explosion source distance on the change rate of floor displacement and story drift. Therefore, allowable safety distance should be determined according to the mining conditions and structural height during structure design.
 
Article
Nowadays, the stress analysis mostly aimed at general buried pipelines. And few of the gas pipelines in tunnel (especially under the seismic action) were analyzed. Therefore, it is necessary to analyze the stress distribution of gas pipeline under seismic action in tunnel. In this paper, CEASAR II software was used to establish the stress model of China-Myanmar XX tunnel pipeline under seismic action, based on the seismic spectrum. A pipeline dynamic stress analysis was performed by inputting spectral parameters of gas pipeline, and the results indicated whether or not the pipeline displacement and stress under a violent seismic action would conform to specification. We came to that: (1) In general, the most dangerous section of the pipe is the bend. Measures to control stress should be taken to reduce the stress. (2) Axial seismic action and comprehensive seismic action effected by greater impact on pipelines. Therefore, the stress variation at the axial seismic and comprehensive seismic action should be focused on. (3) Through the displacement checking of the pipeline, the effect of axial seismic action and comprehensive seismic action to displacement was larger. (4) Unlike buried pipeline, the axial displacement was large compared to other two direction displacement. And strengthening the monitoring efforts was necessary.
 
Properties of Fly Ash 
Details of Mixture Proportion
Article
The development of alkali-activated binders seems to present a greener alternative to OPC. The present study has been made on the low calcium fly ash with alkali activator as an alternative binding material as mortar. The mortar has been prepared with ennore sand and Indian fly ash mixed with alkali activator fluid consisting of sodium silicate and sodium hydroxide of different concentrations. The effect of various parameters such as fluid to fly ash ratio, concentration of alkali activators, curing temperature and duration of curing on the compressive strength of mortar at different ages of 3,7, 28 days has been incorporated. 48 hours curing at about 60-70 0 C seems to be optimum for the present alkali activated fly ash mortar.
 
Article
As the core of digital elevation model, interpolation methods have been run through the each link, such as production, quality control, accuracy assessment, analytical applications and etc. The local radial basis function interpolation method based on spatial relationship of natural neighbor was proposed in this paper. The interpolation reference points were chosen by the Delaunay Triangulation. The first-order and second-order neighboring of interpolation points as the interpolation reference points were used to construct local radial basis function. This method was applied to the construction of digital elevation model, and the correspondent errors were analyzed. Experimental result shows that the method has a good effect on the construction of different landform.
 
Article
In order to meet the needs of performance-based seismic design, a new type of adaptive-slit shear wall that is easy to construct and behaves well under cyclic loading is introduced to improve the seismic performance of conventional shear wall structures. The seismic damage of an adaptive-slit shear wall develops gradually and it transforms from integral wall into slit wall. The mechanical characteristics of adaptive-slit shear walls suggest that such walls are adaptive to various seismic requirements under earthquakes of different intensities. Compared with conventional shear walls, the new wall is highly ductile and is advantageous in controlling the seismic damage process.
 
Article
This paper suggested a new connection protocol, adding cover-plate between shear links and column, which was used to enhance moment and shear carrying capacity of beam, relax the restriction and assure the sufficiency development of plastic deformation of the link, and dissipate more earthquake energy. Considering the scale ratio of 1:3, the experimental data was achieved by a specimen under cyclic loading, which was verified by nonlinear finite element analyses. Results indicated that the new type of eccentrically braced steel frame has enough stiffness and deformation capacity, draws link away from flange of column, and dissipates more earthquake energy. The single diagonal eccentri- cally braced frames adopted adding cover-plate protocol would ensure sufficient lateral stiffness under ordinary circum- stances, including lateral loads due to wind and moderate seismic disturbances, have preferable resisting seismic behavior under rare earthquake, and be so practical and costly that they could be easily applied in the present project. Some factors which affect resisting seismic behavior were the thickness of the connection-plate between beam and column, adding stiffeners, and the decrease in the length of A segment etc.
 
Article
Background Geopolymeric binders are especially indicated when reusing a wide diversity of wastes. This is an important feature, especially in the European context, in which a circular economy and future zero waste are targeted. Still, the cost of these materials, due to the use of high purity activators, prevents their commercialization as they are simply not competitive enough. Objective The reduction in the amount of activators could be a cost-efficient solution if the associated decrease in the mechanical properties turned not to be excessive. This means that it is important to investigate the manner in which these additives can be used on their composition in order to compensate that mechanical reduction. Results and Conclusion This paper discloses results concerning the mixed design of fly ash based geopolymeric mixtures using metakaolin, Portland cement (OPC) and calcium hydroxide as additives. Their influence on the mechanical properties, microstructure and cost-efficiency was studied. The results showed that the use of Portland cement as an additive leads to lower compressive strength. Results also show that geopolymers with different additives have different optimum Na 2 SiO 3 /NaOH ratios.
 
Composition and properties of cement, micro-silica and nanosilica.
Article
Background Nano-silica is a new pozzolan that is boosting the field of nanomaterials and can be used effectively in the concrete industry. ASTM C1240 is used to qualify silica fume pozzolans for use in concrete and for marketing purposes. Objective The present study aims to assess the adequacy of ASTM C1240 in qualifying nanosilica for use in concrete and to introduce a modified procedure to measure the pozzolanic activity of nanosilica used with cementitious composites. Methods The effects of various particle sizes and dosages on the compressive strength of blends in standard mortar were investigated. The correlation between the chemical reactivity and the compressive strength were also investigated using TGA and XRD analyses. The criterion conceived was validated at two ages: 7 days and 28 days. Results and Conclusion The strength activity index results revealed that the following standard procedure ASTM C1240 is not applicable for nanosilica due to the high surface area and great pozzolanic reactivity of SiO 2 nanoparticles, so a lower cement replacement percentage should be used. This study suggests that it be no more than 7%. The pozzolanicity testing results confirm that a nanosilica replacement level of more than 7% could not be effective in transforming further Portlandite into a C-S-H or other major cementing compound, leading to a “false negative” for nanosilica pozzolans.
 
Article
This paper introduces the research status and analysis of the Multi-Extruded-Expanded-Plates pile (the MEEP pile) at home and abroad, by studying when the plate of pile embedded in different characteristics soil layer, the thickness, physical properties of upper and lower soil layer adjacent to the soil with plate cause the influence on soil break and bearing capacity of the soil layer with plate, analyzing the work together with pile and soil in different soil layer, providing a theoretical basis to improve the calculation formula of bearing capacity of single pile, ensuring the rationality and reliability of the design of the MEEP pile.
 
Conference Paper
Uncontrolled, unreasonable foundation pit dewatering is often the primary cause of deformation of nearby buildings. It is therefore imperative to diminish or eliminate the negative influence during dewatering. This paper describes the application of artificial recharge to rectify adjacent building deformation due to pumping. Bases on the principle of potential function superposition, a water line equation with pumping and injection wells steady or unsteady simulations operate in a confined aquifer are deduced, thereby an "influence radius" concept for unsteady flow is proposed. Through a project example, the control effect of recharge for nearby building deformation due to pumping is evaluated, results of which confirms that recharge can be used as an effective management methods. Moreover, some suggestions about the layout of recharge wells are put forward.
 
Comparison of time histories of the relative displacement of the top floor. 
Article
Introduction Seismic isolation has been proven to be an efficient approach to seismic retrofitting of structures based on the concept of reducing the seismic forces by lengthening the structural fundamental vibration period. However, superstructures may collide with each other under seismic excitation as the top displacement increases in the case of base-isolated adjacent structures. The relative displacement of top floors of superstructures is decreased more effectively by connecting the isolation layer of adjacent structures with a large floor, compared with the method to increase the width of seismic joint by using building monolithic movement technology. A specific engineering of base isolation for retrofitting of existing adjacent frame structures is studied in this paper. Methods Seismic response was evaluated for the structures in different cases by time-history analysis. Parametric studies are performed in order to achieve the laws of top displacement difference of superstructures influenced by the change of dynamic characteristic of towers in the case of base-isolated multi-tower structure with a large floor. Results and Conclusion The results of extensive numerical analysis verify the effectiveness of isolation with a large floor in minimizing the forces from earthquake and protecting the top story from crashing into each other, which has important reference value for application of retrofitting with isolation technology on adjacent reinforced concreted frames.
 
Article
Three-dimensional model is established with finite difference method to simulate construction process based on design and construction plans of existing overpass pile foundation adjacent to certain large-section railway tunnel in Chengdu, China. Ground, isolation pile, main bridge pier and ramp pile near the tunnel are taken as research object, and surface settlement amount, displacement change law of each pile foundation and structural mechanics property are analyzed to further judge whether safety of adjacent overpass structure can be ensured during construction in accordance with used tunnel design and construction plans. Research result shows that the maximum value of surface settlement amount is 13 mm, and settlement range is within 8 m at two sides of tunnel axis; and the settlement amount of pile top of main bridge pier is greatest, referring to 47 mm. Axial force and bending moment borne by the main bridge pier are greatest, and horizontal displacement and bending moment distribution at different positions of the main bridge pier at two sides of the tunnel have the characteristics of right-and-left symmetry, and point of inflection is at the position being 1/3 of pile length away from the pile top, while point of inflection of isolation pile is at the position being 2/5 of pile length away from the pile top, and reinforcement of the pile body may be adjusted accordingly. The pile with minimum safety factor is the isolation pile which is closest to the tunnel, and the minimum safety factor is 3. 5. As displacement value of each pile foundation is within allowed range, and safety factor meets standard requirement, so construction as per the design and construction plan may ensure safety of adjacent overpass structure.
 
Article
The air shaft deep foundation pit 6 is influenced by subgrade unbalance loading of highway 312, specifically its deep horizontal displacement of supporting piles and subgrade settlement of expressway 312 under unsymmetrical load effect. This paper carries out construction monitoring and numerical simulation analysis and gives a detailed study on the influenced factors of support structure deformation. Calculation results show that subgrade unsymmetrical load has a great influence on deep horizontal deformation of supporting piles. The maximum horizontal displacement at the bias side is about three times more than non-bias side’s; when the distance of subgrade to foundation pit is the same as the depth of excavation, the influence of subgrade on pit can be ignored; as the cohesion and internal friction angle increases, the horizontal displacement of fender piles decreases. However, enlarging the embedded depth of supporting piles has no significant influence on the stability of foundation pit.
 
Article
Aerodynamic admittance is a key parameter affecting the analysis accuracy of the bridge buffeting response. However, few articles have covered the issue of the wide-body flat box girder with much smaller depth-width ratio (such as 1/12 studied in this paper). Therefore, to explore the real buffeting force of the wide-body flat box girder, experiments of the static force coefficients and aerodynamic admittance are carried out in wind tunnel. Wooden segmental model has a scale ratio of 1/60 to an actual 42 m wide suspension bridge girder. Using the high-frequency-force-balance (HFFB) equipment fixed with the segmental model under the conditions of different wind speeds and different wind attack angles, wind power spectrums of the buffeting force are measured and the variation of aerodynamic admittance parameters is analyzed. The results show that the aerodynamic admittance of the box girder measured in the experiment with this so much smaller depth-width ratio differs from the corresponding classical Sears expression. Some inspiration can be presented for the future study of the buffeting response for this kind of much wider bridge with the similar ratio in this paper.
 
Article
With respect to the recent issue related to the lack of research on tensile creep model of the admixture concrete at early age and simulation, the admixture influence function with factor of the admixture dosage was established based on composite exponential function as reference model based on existed creep rules and appropriate assumption. It has been proposed that contributing factor, c, quantitatively represented the sensitivity of concrete creep changes to the admixture and correlation between concrete creep and the admixture. The model fitting was then made after tensile creep experiment by adding different admixtures such as fly ash, slag, silica fume and polypropylene fiber in contract to reference concrete test. It indicated that the model exhibited a good fitting performance, which is practical and useful as well as readily adopted by simulation. Meanwhile, the contributing factor also demonstrated quantitatively the variation among the effect of the admixtures (fly ash, slag, silica fume and polypropylene fiber) on the tensile creep of the concrete. Finally, the model was applied to an as-built concrete project for extended simulation, the results indicated that tensile creep can effectively improve the distribution of surface tensile stress and alleviate detrimental effect due to day-night temperature differences.
 
Article
In order to study life support key techniques in mine refuge station, test the clinical emergency response of participants and human survival parameters in rescue state. A manned test with 50 miners for 48h in a real underground refuge station was conducted in Guilaizhuang gold mine. The experiment simulated rescue living environment of human and consisted of three stages (the passive stage, the compressed air supplying stage, and the compressed O supplying stage). By monitoring environmental concentrations of O 2 , CO 2 , temperature, relative humidity, and human activity states during the test, the O 2 consumption, CO 2 production and respiration quotient was obtained and analysed in different activities, time quantum and O 2 concentration. On the basis, the minimum air supply volumes for the survival of test personnel were determined. That is 0.067m/min per person and is far lower than the national standard 0.3m/min per person. During the test, no people experienced discomfort by health check and questionnaire. It is expected that the conclusions provide an important reference for the design of underground refuge stations and mine emergency rescue.
 
Article
By taking the super-long railway tunnel as the object of research, based on setting problems of emergency stations adopted by super-long railway tunnels, from the viewpoint of people's safe evacuation, several aspects were studied, such as the mode of evacuation and rescue by adopting emergency station, the number and interval of the cross passage, and the people's safe evacuation time under different fire scenes at the emergency station. The basis for optimal design and construction of the emergency station in the super-long railway tunnel was provided, and it has vital practical significance to the perfection of fire emergency rescue and safe evacuation plan in super-long railway tunnels.
 
Article
In the tunnel construction, due to the limitation of the survey and design and the complex dynamics of tunnel surrounding rock geological conditions, so it is difficult for complex geology with the microscopic accurate grasp, often which caused by geological exploration data do not tally with the actual situation, often encountered in karst water inrush, large deformation in weak rock, cave-in subsidence, geological hazards, such as gas outburst, rock burst cause person casualties, delays, in order to minimize geological disaster influence degree, advanced geological prediction before construction is very necessary. Using regression analysis, based on engineering vault subsidence and horizontal convergence has carried on the regression analysis, research results can be reference for related engineering design and construction. Detailed introduces the principle, methods and outstanding characteristic of tunnel reflection tomography advanced prediction system, and take Jianfengling mountain tunnel of Darui line railway as an example, the prediction results are analyzed in detailed processing, and on-site validation, finally points out the problem for further study the technology.
 
Article
Solid Isotropic Microstructure with Penalization(SIMP) in topology optimization was deeply analyzed, and thus SIMP topology optimization criteria algorithm was deduced. Simulation analysis to the results was also conducted by Ansys, so as the structural lightweight design to machine crossbeams of the HTM series gantry. By verifying, the structure was 3.8% lower than the traditional structure quality, stiffness increased by 16.07%, and the overall inherent frequency was improved. By applying topology optimization method to the design process of the machining center HTM series, material utilization is improed and production costs were reduced.
 
Article
Background The Architecture, Engineering, and Construction (AEC) industry is one of the sectors that contribute the most to the Palestinian economy. However, it now suffers from many problems, one of which is not adopting new innovations, such as Building Information Modeling (BIM). BIM recently achieved far reaching consideration in the AEC industry. Aim This research aimed to understand the contribution of BIM to the enhancement and application of Knowledge Areas (KAs) in the AEC industry in Palestine. Methods A quantitative survey was utilized in the pilot study. Thirty copies of the questionnaire were dispersed to respondents from the target group. The completed questionnaires were analyzed to test for statistical validity and reliability. After the pilot study, the questionnaire was validated and dispersed to the entire sample, comprising respondents from the target group who were selected by convenience sampling. Eighty copies of the questionnaire were dispersed, and 71 copies of the questionnaire were obtained from the respondents with a response rate of 88.8%. Results To draw meaningful results, the gathered information was analyzed by utilizing quantitative data analysis techniques, including the RII, Pearson correlation analysis, and Factor analysis. Conclusion The results illustrated the extent of enhancing the application of KAs in the AEC industry using BIM technology from the highest to lowest as follows: Cost Management (CM), Time Management (TM), Resource Management (REM), Procurement Management (PROM), Scope Management (SCM), Stakeholder Management (STM), Integration Management (IM), Quality Management (QM), Communication Management (COM), Risk Management (RM), and Safety Management (SM). As an example, BIM is effectively applied to each KA, and high efficiency is achieved when BIM is applied to TM by 4D modeling; to CM by 5D modeling; to REM by collaboration; to PROM by quantity takeoff; to SCM by element-base; to STM and IM by using integrated project delivery; to QM by using clash detection; to COM by centralized, structured data management, and information flow; to RM by constructability; and to SM by automated safety code checking.
 
Size distribution plots for CFBC fly ash and ground MSWI bottom ash. 
Compressive strength values of AAC samples. 
Drying shrinkage of AAC0, AAC2 and AAC4 specimens. 
Article
Background Municipal solid waste incineration (MSWI) bottom ash contains a not insignificant amount of metallic aluminum, while circulating fluidized bed combustion (CFBC) fly ash is rich in active SiO 2 . Objective To reduce the materials cost of autoclaved aerated concrete (AAC) production, these two types of solid waste could theoretically be used as the aerating agent and silica source, respectively. Method In the present work, the metallic aluminum concentration in an MSWI bottom ash sample was determined from hydrogen generation and this ash was used to make AAC in conjunction with CFBC fly ash. The extent of air entrainment in the resulting AAC specimens was varied by changing the bottom ash to fly ash ratio, and the effects of this ratio on the properties of the AAC were investigated. Results Results showed that the ratio has a negligible effect on both the type and the morphology of the hydrates in the AAC, but is inversely proportional to the compressive strength, density and volume stability. Conclusion This study proves that AAC having satisfactory properties can be successfully prepared from a combination of MSWI bottom ash and CFBC fly ash.
 
Top-cited authors
Samuel Sakyi Koram
  • Jiangsu University
Bassam Tayeh
  • Islamic University of Gaza
Gabriele Milani
  • Politecnico di Milano
Antonio Formisano
  • University of Naples Federico II
Yajun Liu
  • Georgia Institute of Technology