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The government of India has embarked on the construction of major highways with concrete pavements to eliminate frequent maintenance of bituminous pavement, damaged by heavy commercial vehicles and moisture. Hence, it is necessary to re-examine the current pavement design with a sound analytical approach. The current practice in the construction of concrete pavement in India is to place pavement quality concrete (PQC) over dry lean concrete (DLC) layer with a bond-breaking layer of 125-micron plastic sheets between the DLC and PQC layers to eliminate possible reflective cracks from the DLC to the PQC layer. Concrete pavement can be bonded to lean concrete (LC) when both layers are laid one after the other with two pavers (‘fresh-on-fresh’ or ‘wet-on-wet’). This type of pavement is also known as twolift concrete pavement (TLCP), and such pavements were constructed in India during the last three years. No readymade solutions are available to compute stresses in such TLCPs. The objectives of the research are manifolds. Firstly, this article illustrates the analysis of Two-Lift Concrete Pavement (TLCP) using Finite element programming software (ANSYS) with an interface layer CONTA 174, which is able to capture interfacial stresses occurring between layers due to non-linear temperature gradient distributed over the depth of the slab. Then the design of pavements with TLCP has been introduced using the cumulative fatigue damage method. Finally, the cost of construction for TLCP is determined and compared with that of conventional concrete pavement. It was found that the material cost for TLCP is less than that of conventional concrete pavement because the stresses induced due to both load and environmental effects in TLCP are significantly lower when compared to those on the conventional concrete pavement.

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... The following approaches were adopted to compute stress, strain and displacement at various locations. • Closed-form solutions -Westergaard (Westergaard, 1926b), Modified Westergaard (Bradbury, 1938), etc. • Finite Difference Method (FDM) (Wang et al., 2009) • Finite Element Method (FEM) -High-end computational software like ABAQUS (Uddin et al., 1995), AnSYS (Swarna et al., 2021), etc., are used in FEM. Some of the software developed by a few states' Department of Transportation (DOT's) such as the Oregon Department of Transportation (ODOT), Mechanistic-Empirical Pavement Design Guide (MEPDG), etc. ...

... • 2D Finite Element Solutions: KENSLABS (Huang & Wang, 1974), ILLISLAB (Tabatabaie & Barenberg, 1980;Tabatabaie-Raissi, 1977), ILSL2 (Khazanovich, 2003) and ISLAB2000 (Khazanovich, 2003). • 3D Finite Element Solutions: EverFE (Davids et al., 1998), CHEVRON (Ramsamooj, 1999), ANSYS (Maitra et al., 2009;Swarna et al., 2021), ABAQUS (Kuo, 1998). ...

... These cracks can happen either due to traffic or environmental loading. If the slab width is more than 5.2 m (Swarna et al., 2021), (Heath et al., 2003) a possible shrinkage gradient together with a negative temperature gradient can cause top-down cracking. However, in most cases, bottom-up cracking occurs because of traffic and environmental loading. ...

Despite the cost-effective nature of asphalt pavements, concrete pavements are preferred for their superior serviceability. Many agencies use Jointed Plain Concrete Pavement (JPCP) designs with a standard slab size of 3.5 × 4.5 m, focusing on transverse cracking. However, night-time Longitudinal Top-Down Cracking (LTDC) can occur in widened slabs due to tandem and tridem axles. This study employs a Finite Element (FE) approach to assess wider slabs under various loads. Longitudinal tensile stresses at critical points were found to increase with the slab width. Therefore, the study emphasizes the need for a design approach addressing transverse and longitudinal cracking. The design of the wider slabs (4.5 × 4.5 and 5.0 × 4.5 m) is demonstrated using a case study. If the longitudinal joint in a 9.0 m slab is placed at 5.0 m from the edge, the pavement could perform better than other slab sizes. However, it is necessary to design the pavement considering both longitudinal and transverse cracking. ARTICLE HISTORY

... Although 2LCP is becoming a technically feasible technique, successful implementation of the technique will require more demonstration projects to promote the practice and to eliminate difficulties and challenges for 2LCP implementation demands laboratory and field studies to determine optimum time lag between the two lifts under different conditions, minimum bond strength, and CoTE on debonding issues and/or thermal deformation. Several full-scale demonstration projects (Cable J. K et al. (2004), Brand A et al. (2014)., Hu J et al. (2014) and Swarna S et al. (2019) report that two-lift construction offers an economic solution with almost similar performance as the conventional. ...

Now-a-days concrete pavements are gaining more and more importance to eliminate regular maintenance of asphalt pavement, damaged due heavy traffic and moisture. Several types of plain concrete pavement are in use in various countries depending upon the climate, availability of materials, soil types, experience, and traffic. It is therefore necessary to improve the current pavement design with a sound analytical approach. To lower the cost of construction of concrete pavements, researchers came to a new type of concrete pavement construction named Two-Lift Concrete Pavement (TLCP). In this type of pavement construction, Pavement Quality Concrete (PQC) can be bonded to lean concrete (LC) when both layers are constructed one over the other with two pavers (“fresh-on-fresh” or “wet-on-wet”). No analytical techniques are available to compute the stresses in TLCPs. To compute the stress in TLCP under various environmental and loading conditions, a finite-element programming software (ANSYS) is used. These stresses place an important role in determining the design of concrete pavements. To achieve this, a Central-Composite design with face-centered statistical design is utilised. In this design, statistical assumptions such as Normality, constant variance and Independence are checked and found that all assumptions are acceptable, but box-cox suggested to transform the model to square root. So, the model is transformed to square root form. The statistical model is validated using four random points and it is noticed that the model satisfies all the points. Conclusions are drawn from the interaction plots of the model. From the model, it is noticed that the factors such as temperature gradient over the depth of the slab and modulus of subgrade reaction are insignificant but when it interacts with other factor (PQC thickness and LC thickness), the interaction became highly significant.

... Yeon and Kim (2018) found that phase change materials (PCMs) have a positive effect on alleviating freeze-thaw degradation of concrete pavement, which became minimal when the ambient temperature was much lower than the transition temperature. In India, 2LCP is often constructed by paving pavement quality concrete (PQC) over dry lean concrete (DLC) and adding micron plastic sheets between layers to eliminate interlayer reflective cracks (Swarna et al., 2021). ...

Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges. In the past 10 years, the pavement infrastructure strongly supports the rapid development of the global social economy. New theories, new methods, new technologies and new materials related to pavement engineering are emerging. Deterioration of pavement infrastructure is a typical multi-physics problem. Because of actual coupled behaviors of traffic and environmental conditions, predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis. In order to summarize the current and determine the future research of pavement engineering, Journal of Traffic and Transportation Engineering (English Edition) has launched a review paper on the topic of “New innovations in pavement materials and engineering: A review on pavement engineering research 2021”. Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering, this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world. The content includes asphalt binder performance and modeling, mixture performance and modeling of pavement materials, multi-scale mechanics, green and sustainable pavement, and intelligent pavement. Overall, this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.

... In the case of bonded concrete pavements, monolithic slab behaviour is observed. The studies have indicated that bonded concrete pavement may be designed to be marginally thinner PCC slabs compared to un-bonded concrete pavements (Swarna et al., 2018(Swarna et al., , 2021. Further, the numerical analysis by Fang et al. (2013) have shown that an increase in the lower/base layer thickness reduced the load related stresses in two-lift concrete pavement. ...

The transformation in axle loads of vehicles along with environmental factors requires stiff base layer for concrete pavement and one such stiff layer is dry lean concrete (DLC). The DLC would have variable stiffness as a result of the construction practices. The present study focuses on understanding the influence of DLC stiffness on the tensile stresses in plain cement concrete (PCC) slab using Finite Element (FE) analysis. The PCC slabs are analyzed considering various cases: bonded and un-bonded base with positive and negative temperature differentials. From FE analysis, it is observed that an improved DLC base stiffness has a more pronounced effect on stresses to recede in the PCC slab of bonded concrete pavement with a positive temperature differential. The influence of DLC stiffness was less in the bonded concrete pavement with a negative temperature differential, while marginal in un-bonded concrete pavement with positive and negative temperature differentials.

... It is concluded that although two-lift paving construction generally has a higher cost associated with the additional equipment, labor and scheduling efforts, the cheaper bottom lift material can compensate for that increased cost. Swarna et al. (2019) developed finite element models of two-lift wet on dry concrete pavements and have simulated thermal and structural loads for evaluating the performance of such system. It was concluded that, compared to conventional pavement construction, the two-lift construction with more inexpensive material can result in the desired structural adequacy. ...

This year marks ten years since the Great East Japan Earthquake in 2011 and the following Fukushima Daiichi nuclear accident. This accident has created a critical need to quantify the seismic response of such critical structures under different levels of seismic hazard. Most seismic-related research studies have been conducted on reinforced concrete walls employed in conventional buildings; however, such walls in nuclear and industrial structures are uniquely designed with very low aspect ratios and relatively large thicknesses. Therefore, several studies have demonstrated that the seismic performance of reinforced concrete walls in nuclear and industrial structures has not been yet adequately quantified to enable robust seismic risk assessment. In this respect, the current study uses a multi-layer shell element in OpenSees to develop a numerical model that can simulate the seismic response of reinforced concrete shear walls with low aspect ratios similar to those used in nuclear and industrial structures. Subsequently, the developed model is validated against the results of several walls tested in previous experimental programs under cyclic loading. The validation results show that the developed model can capture the response of the walls including the initial stiffness, peak load, stiffness degradation, strength deterioration, hysteretic shape, and pinching behaviour at different drift levels.

Constructing structures with the lowest possible use of the material has long been an interesting topic among engineers. In this regard, the resilience of structures in the face of natural hazards and their concomitant effects, such as the resonance phenomenon, should also be taken into account. Frequency-constrained optimization problems seek to not only construct structures with the least possible material amount, but also prevent the resonance phenomenon, enhancing the sustainability of the structures by reducing the total material consumption while minimizing the future damage cost incurred by structural components due to this effect. This article assesses the truss optimization problems with natural frequency constraints using the improved version of the newly developed meta-heuristic algorithm, referred to as the water strider algorithm (WSA). Improved water strider algorithm (IWSA) utilizes two mechanisms to improve the performance of WSA. The first one is the opposition-based learning (OBL) technique, and the other is a mutation method. The OBL technique for the initial population improves the convergence rate and the accuracy of the final result, and the mutation method helps it to approach the global optimum and avoid the local one. Three benchmark spatial truss optimization problems are selected from the literature to examine the efficiency of IWSA in comparison to other well-established algorithms as well as its standard version, WSA. The results reveal the viability and competitiveness of the IWSA algorithm in the framework of design optimization with frequency constraints in comparison to its standard version and other structural optimization algorithms.

The present study has examined the two-lift concrete pavement (2LCP) fracture and mechanical behavior by casting the Roller Compacted Concrete (RCC) as the bottom lift and the conventional or fibrous Portland cement concrete (PCC, FPCC) as the top lift. To this end, the three-point bending test was carried out on notched beams by considering different thicknesses for both layers. Results showed that fibers had no positive effects on the compressive and flexural strength, but improved the post cracking behavior considerably. Compared to full-depth RCC/PCC, 2LCP specimens had similar flexural strengths, but an increase in the FPCC top-layer thickness increased the fracture energy noticeably.

The current practice in the construction of jointed plain concrete pavements in India is to lay paving quality concrete (PQC) over roller-compacted concrete designated as dry lean concrete (DLC). A 125-μm plastic sheet is placed as a bond-breaking layer at the interface of the DLC and PQC. By placing the PQC layer directly over fresh lean concrete (LC), the two layers will bond without any extra bond-breaking layers, and there may be a considerable reduction in PQC thickness. Reducing the PQC layer thickness decreases the amount of aggregates used, which helps preserve quality aggregates that are rapidly depleting. Pavements in which the PQC is laid directly over LC can be designated as a two-lift concrete pavement (TLCP). Joints must be provided with deep saw cuts to avoid random cracking. The LC can be made up of recycled concrete or marginal aggregates to obtain a sustainable pavement. However, readymade analytical solutions are not available for the computation of stresses in two-lift bonded concrete layers for pavement design. This article presents a three-dimensional finite element solution for stresses in bonded concrete pavements. Stresses in both layers are presented in order to arrive at an optimum thickness combination so that both layers are safe during the design life. Stress computation is done for the conditions of simultaneous application of temperature gradients and axle loads. The cracking of the LC layer because of high flexural stresses at the bottom is found to be the critical factor in the design of TLCP.

Full-depth and two-lift concrete slabs were cast with fractionated reclaimed asphalt pavement and recycled concrete aggregate as partial and full replacements of the coarse aggregate in a ternary blend concrete containing cement, slag, and fly ash. These large-scale slabs were monotonically loaded at the edge to quantify the effect of recycled aggregates on the slab's flexural capacity. Although the introduction of these recycled aggregates into the concrete reduced the compressive, split tensile, and flexural strengths as well as the elastic modulus of the concrete relative to virgin aggregate concrete, fracture testing demonstrated that recycled concrete aggregate can have fracture properties statistically similar to those of virgin aggregate concrete. Testing of the flexural capacity of the slabs revealed that concrete with recycled aggregates had peak loads at failure similar to or greater than those of virgin aggregate concrete despite a significant difference in beam flexural strength. The calculated tensile stress in the slab at flexural failure was underpredicted by the beam flexural strength by a factor of 1.5 for virgin aggregate concrete and 1.9 to 2.7 for concrete with recycled aggregates; these findings demonstrate that the beam flexural strength results are not always reliable predictors of slab capacity, especially with recycled aggregates. Because of lower beam flexural strengths with recycled aggregates, pavement engineers should compare the fracture properties of concrete containing recycled aggregate with those of typical virgin aggregate concrete before deciding whether to increase the required concrete slab thickness.

Two-lift concrete paving (2LCP) involves placing two layers of concrete (wet-on-wet) instead of a single homogeneous layer. The practice not only allows the use of local aggregates that might not be suitable for conventional pavement, but also provides opportunities for incorporating recycled materials and higher levels of supplemental cementitious materials (SCMs) to produce an economical and sustainable pavement. The practice can also produce durable pavements through the optimization of top lift mixture design with desirable surface characteristics including improved skid resistance and reduced noise. While 2LCP could become a viable and competitive alternative to conventional single-lift paving, challenges of 2LCP are to have the proper paving equipment and pavement construction management, the right mixture proportions to ensure the use of local materials in the bottom lift to result in an economical placement and to ensure a high quality top lift. Through information collected from an extensive literature review, surveys, interviews and a recently hosted 2LCP workshop, a summary of benefits of 2LCP from sustainability and cost effectiveness perspectives was provided. Four 2LCP projects recently constructed in the U.S. were summarized as case studies. This paper also discusses additional requirements in materials, equipment and construction, project scheduling and jobsite management, which will be beneficial in the implementation of 2LCP construction.

The frictional force between concrete slab and subbase is accompanied by horizontal slab movements induced by variation of temperature and moisture in the concrete slabs. The frictional force is exerted in the opposite direction from the horizontal slab movement and causes stress in the slab. Rational evaluation of subbase friction is important in configuring joint sealing, slab thickness, and reinforced steel. Determination of the subbase friction is also required as an input for the recently developed concrete-pavement-construction program HIPERPAV. Lean concrete has been widely used as the typical subbase for jointed concrete pavement in Korea. Generally, polythene sheet is placed between the lean concrete subbase and the concrete pavement slab as a friction reducer. In addition, an asphalt bond breaker may be used as an alternative friction reducer in some cases. Three series of push-off tests were conducted to study the characteristics of subbase friction for this typical Korean jointed concrete pavement system under three different subbase conditions (I, test slab directly cast on lean concrete subbase; II, polythene sheet placed between test slab and lean concrete subbase; and III, 4-cm asphalt bond breaker placed between test slab and lean concrete subbase). For each series, tests were performed under various conditions (rate of movement, slab thickness, number of movement cycles) to investigate the influence of these potential factors on the development of subbase friction.

In a jointed concrete pavement, the dowel bar system and the aggregate interlock are two mechanisms for transferring wheel loads from one panel to the adjacent panel. The aggregate interlocking load transfer mechanism is effective for narrow joints while the dowel bar system works well for both narrow and wider joints. This paper examines the effects of different parameters on load transfer efficiency of a joint with the help of a three-dimensional finite-element model for the analysis of a dowel-jointed concrete pavement. The model was compared using experimental data available in the literature. The group action of the dowel bar system was also examined and useful relationships have been developed for estimation of the relative load shared by the individual dowel bars. These relationships will be useful in the design and evaluation of dowel jointed concrete pavements.

Nonlinear finite element analysis of dowel-jointed concrete pavements is presented. The nonlinearities considered are cracking of concrete in tension, compressive yielding of concrete, and loss of support due to lift-off of pavements because of temperature gradients. Smeared cracking representation of cracks in concrete and a plasticity-based material model are employed. Loss of support due to removal of subgrade material through pumping is considered. Analysis of a doweled joint subjected to shear loading is performed to obtain dowel-concrete interface response characteristics. Analyses of plain concrete pavements subjected to self-weight, temperature gradients, and static wheel loads are performed with four different extent of loss of subgrade support and two different dowel-concrete interface characteristics. The loss of subgrade support may lead to a rapid deterioration of pavements through fatigue, by increasing the tensile stress level in concrete. Faulting of slabs may also be due to loss of support at the far end of the slabs. Softening of the dowel-c0ncrete interface stiffness significantly affects the efficiency of the joint in transferring the loads. Nighttime temperature curling further increases the stresses due to lift-off of slabs at the ends, while daytime temperature curling is found to be less critical.

Performance of concrete pavements is controlled by the behavior and performance of the jointing system used, especially the performance and load transfer efficiency of the joint. A finite-element program is presented that includes the analysis of slabs with various joint systems in PCC pavements. Dowelled joints, joints with aggregate interlock, and joints with various types of load transfer schemes can be taken into account during the analysis of the slab under load rather than analyzing the slab and joint systems separately and superimposing the results. The program described is also capable of analyzing slabs comprised of two layers with different material properties, either bonded together or unbonded. Slab thickness, slab modulus values, and subgrade support values can each be varied at each node point in the program to evaluate jointed slabs of nonuniform stiffness and nonuniform support.

The edge loading tensile stress determination in a concrete slab due to individual and combination effects of wheel loading and thermal curling is important to a mechanistic-based design procedure. This paper presents a mechanistic-based approach in developing a predictive model. Through the use of the principles of dimensional analysis, the dominating mechanistic variable were necessary. A new regression technique together with traditional linear and nonlinear regressions were used to develop prediction models. These prediction model provide an accurate representation of the finite-element model.

This paper quantifies the environmental improvements in current versus past pavement materials and construction practices employed by the Illinois State Toll Highway Authority (tollway authority). Improvements in sustainability performance were measured with a life-cycle assessment (LCA) approach. Three scenarios were generated to evaluate tollway authority practices on the basis of eight 2013 Interstate reconstruction and rehabilitation projects. The first scenario, 2013 projects, analyzed the actual pavement material and designs of the 2013 projects. The second scenario, materials baseline, was based on the 2013 projects but modified to include mix designs with less-sustainable materials used by the tollway authority circa 2000. The third scenario, design and materials baseline, considered both mix designs and pavement design practices used circa 2000. To improve the spatial and temporal relevance of the analyses, two regional databases of life-cycle inventories representing processes from 2013 and 2000 were developed and applied to the 2013 projects and 2000 baselines. A tool developed by the Illinois Center for Transportation (ICT) of the University of Illinois at Urbana-Champaign, the pavement ICT-LCA 0.95, was used to evaluate the sustainability performance indicator (SPI), global warming potential (GWP), and cumulative energy demand (CED) for each scenario. The resultant savings in SPI, GWP, and CED from the first scenario ranged between 17% and 28%, 12% and 16%, and 13% and 26%, respectively, compared with the second scenario, and 12% and 33%, 8% and 26%, and 11% and 32%, respectively, compared with the third scenario.

A finite-element method programmed for a high-speed computer was developed for determining the stresses in concrete slabs with load transfer at the transverse joints. The method is based on the classical theory of thin plates on Winkler foundations and yields numerical results that check closely with other available solutions as well as with the experimental measurements from the AASHO Road Test.

The load transfer mechanism between the dowel and the concrete is a complex phenomenon. This mechanism depends mainly on a parameter known as the modulus of dowel support (K), the value of which can be determined by load testing. A high modulus of dowel support value indicates a good contact between the concrete and the steel dowel. There is a lack of sound approach to identify with any degree of accuracy the modulus of dowel support (k), which makes it difficult to rely on the analytically developed formulas that are sensitive to its value. The obtained numerical results were validated with classical analytical solutions of shear and moment along the dowel. The group action of the dowel bar system was examined and useful relationships have been developed for estimation of the relative load shared by individual dowel bars. These useful relationships have been used to developed prediction Model to predict the shear force in dowel group action of dowel bar system and deflection at the loading nodal point. The prediction Model results for shear force in dowel group action of dowel bar system and deflection at the loading nodal point were relatively close to the F.E. Model results, with the different range between 2.2% to 7%.

In 1978, an experimental two-layer concrete pavement was opened to traffic on SR-45 near Fort Myers, Florida. The experimental pavement included a series of two-layer concrete pavement sections with various design features placed over either a granular or a cement-treated subbase. These sections consisted of a 3-in. (7.5-cm) portland cement concrete (PCC) surface over a 9-in. (23-cm) lean concrete (commonly referred to as econocrete) layer. The control section consisted of a standard PCC 9 in. (23 cm) thick with joints spaced at 20 ft (6 m) on a cement-treated subbase. After 30 years of service, the sections constructed over a granular base performed better than those placed over a cement-treated subbase. The distresses on the two-layer concrete pavement sections built on the granular subbase were minimal, regardless of their slab lengths. In contrast, the control section experienced greater cracking, greater corner deflections, and moderate-to-severe spalling. The findings validate several features of Florida's current design policies, such as limiting joint spacing to 15 ft and prohibiting cement-treated subbases directly below concrete pavements. Furthermore, this project has demonstrated that a two-layer concrete system consisting of a relatively thin high-quality PCC surface over a lower-quality econocrete layer and a granular subbase can be a sustainable and long-lasting pavement design alternative.

Issues related to the finite element modeling of base and subgrade materials under jointed plain concrete pavements are examined. The three-dimensional finite element program EverFE, developed in conjunction with the Washington State Department of Transportation, was employed for the analyses. The relevant modeling capabilities of EverFE are detailed, including the ability to model multiple foundation layers, the incorporation of loss of contact between slab and base, and the efficient iterative solution strategies that make large three-dimensional finite element analyses possible on desktop computers. The results of parametric studies examining the effects of foundation type (layered elastic and dense liquid) and properties on the response of jointed plain concrete pavements subjected to axle and thermal loads are presented. Special attention is paid to the interactions between joint load transfer effectiveness and foundation type, and joint load transfer is shown to change significantly with different foundation models and properties. A consideration of simultaneous thermal and axle loadings indicates that the effect of foundation type and properties on critical slab stresses caused by edge loading and a positive temperature gradient is relatively small. However, the slab response is quite sensitive to foundation type for a combined negative temperature gradient and corner loading. On the basis of these results, use of an equivalent dense liquid foundation modulus in mechanistic rigid pavement analysis or design is not recommended when stiff base layers are present.

A three-dimensional (3D) finite element (FE) model is developed to investigate whether the condition of plane sections remaining plane exists in concrete pavements subjected to nonlinear temperature gradients. This model is utilized to validate the analytical method proposed by Mohamed and Hansen. The 3D brick element is chosen so that the plane section condition is not imposed in the model, as compared with the model using the hat plate element. Furthermore, the possibility of loss of contact between the pavement slab and the subgrade is studied. The condition of full contact is investigated for a nonlinear temperature gradient that produces the maximum tensile stress in the slab according to the data used. Two slab lengths and two radii of relative stiffness are considered. It is found that plane sections remain plane for the entire slab except for a region very close to the free edges, which also establishes the boundary where solutions by Mohamed and Hansen are applicable. In both cases of the contact condition, the 3D FE model predicts no loss of contact between the slab and the subgrade.

The static elastic layer model is customarily used for analyzing deflection measurements and back-calculating pavement layer moduli. Estimation of in-situ layer moduli by means of a mechanistically based iterative technique is known as back-calculation. Despite the fact that the falling weight deflectometer (FWD) load induces a dynamic load, dynamic/impact analysis routines are seldom, because of the mathematical complexity. Dynamic deflection prediction models are developed in this study, which can be used in back-calculation routines. The first step in accomplishing this is to select an appropriate analysis model for which ABAQUS - a general purpose finite-element program - is used. Static and dynamic deflection responses from the ABAQUS model of an uncracked pavement are validated. Following this first step, cracks and joints along with other features of the pavement are modeled in addition to nonlinear behavior of pavement materials. Deflection responses of cracked pavement under a series of increasing loads, assuming linear and nonlinear behavior of base, subbase, and subgrade materials, are computed and compared. After finalizing the model, a synthetic deflection database, specifically with FWD load, is developed relying on a fractional factorial design layout in which thicknesses, layer moduli, and cracks are allowed to vary over a range. Making use of this database, regression equations that predict surface deflection bowls in terms of layer moduli and thicknesses are developed. Deflection equations are validated using field data from two in-service pavements.

This paper develops a solution of warping stresses in concrete pavement slabs resting on a Pasternak foundation. The solution is derived using the classical thin-plate theory. Warping stresses in a slab of length A and width B is obtained by superposing the solution of a slab with length A and infinite width and that of a slab with width B and infinite length. It is shown that the commonly adopted traditional procedure of computing warping stresses with Winkler foundation is a special case of the general solution derived in this paper. The traditional procedure overestimates warping stresses. These stresses decrease as the subgrade shear modulus increases. Comparison with experimental measurements indicates that the present solution produced more accurate warping stresses than those obtained using the Winkter-foundation solution. The derived solution is presented in a dimensionless chart of warping stress coefficients for speedy evaluation of warping stresses in concrete pavements.

Westergaard solutions for maximum bending stress and deflection are derived by assuming infinite slab width and length, and ignoring possible thick-plate behavior of slab under loading. This paper examines the effects of these two factors on Westergaard solutions by comparing with thick-plate solutions for rectangular slabs derived by the writers. The infinite slab assumption is found valid if the slab length is more than four times the radius of relative stiffness. However, because of thick-plate action, not all solutions for slab responses converge to Westergaard values when slab sizes are large. For large slabs where the effect of slab dimensions is negligible, the difference of thick-plate solutions and Westergaard solutions for maximum bending a;tress are less than 15% for square slabs, and less than 20% for 3.66 m (12 ft) wide rectangular slabs. For these large slabs, the values of maximum deflection obtained from the two solutions show good agreement in the case of square slabs. However, for 3.66 m wide rectangular slabs, Westergaard solutions underestimate maximum deflection by 10-70%, depending on the value of radius of relative stiffness of the slab-on-grade system.

The finite-element study of the effect of temperature variation on plain-jointed concrete pavements is presented. Temperature variation causes curling and thermal-expansion stresses. Curling stresses result from temperature gradients through a slab depth. Thermal-expansion stresses are induced due to uniform changes in temperature that cause the slab to expand. The developed three-dimensional (3D) model consists of four slabs separated by longitudinal and transverse joints. The interaction between the ground and the concrete slab along with interaction at the joints were modeled using interface elements. These elements gave the model the capability to solve for partial contact between curled slabs and the ground to investigate the effect of compressive stresses that may develop at the joints during curling, and to study the influence of friction between slabs and the ground. The data obtained using the finite-element model has shown reasonable agreement with the results obtained from three computer models: KENSLABS, ILLI-SLAB, JSLAB, and the analytical solution proposed by Bradbury. The best correlation was obtained with JSLAB. The model was used to perform parametric studies on curling and thermal-expansion stresses to study the effect of superposition of both stresses and to address the effect of uniform temperature changes on joint opening. Another simpler model using nine layers across the depth of a pavement slab was used to introduce the effects of nonlinear temperature distribution. The results of the parametric studies are presented and compared with other solutions. The arithmetic addition of positive curling stresses and thermal-expansion stresses were less than those stresses obtained by superposition. In some cases, the calculated joint openings were higher than the allowable joint opening. Nonlinear temperature distribution caused higher tensile stresses than the Linear distribution of temperature. The difference in tensile stresses between the two distributions was approximately 3-13% of the modulus of rupture of concrete.

This parer exarnines the use of Pasternak foundation model in the analysis of load-induced concrete pavement deflections and bending stresses, as well as thermal stresse caused by warping of slabs. Using theoretical solutions developed by the authors for strctural responses of slabs supported on Pasternak foundation, predicted slab deflections and bending stresses are computes and checked against actual field data. The field data, containing pavement responses under applied loads and thermal gradients respectively, are obtained from the results of full-size slab experiments reported in the literature. Satisfactory slab deflection and bending stress predictions by the Pasternak solutions can be obtained by calculating subgrade shear modulus as the product of modulus of subgrade reaction and a coefficien θ. With reference to actual field measurements, the analysis in this study indicates that using a constant θ value of 0.35 m2 in the proposed Pasternak foundation model would achieve 1% to 25% improvements in the accuracy of pavement responses predictions as compared with the corresponding solutions given by models with Winkler foundation.

Winkler or dense liquid (DL) and elastic solid (ES) subgrade models (figures 1 and 2, respectively) are used most often in pavement modeling. However, neither the DL nor the ES idealization is entirely adequate when applied to real soils and the predictions from both exhibit discrepancies with observed, in situ behavior. The DL model assumes that shear resistance of the subgrade is negligible compared to shear capacity of the subgrade. It models the foundation as a set of independent springs. On the other hand, the ES model attributes to the foundation a higher degree of shear interaction than is usually available in the field. Use of the ES model results in infinite stress predictions under the edges and corners of a plate resting on it. Moreover, both models fail to describe subgrade behavior beyond the slab edge; soil deflections vanish more rapidly than predicted by the ES but not nearly as fast as assumed in the DL formulation.

The features and concepts underlying EverFE2.2, a freely available three-dimensional finite element program for the analysis of jointed plain concrete pavements, are detailed. The functionality of EverFE has been greatly extended since its original release: multiple tied slab or shoulder units can be modeled, dowel misalignment or mislocation can be specified per dowel, nonlinear thermal or shrinkage gradients can be treated, and nonlinear horizontal shear stress transfer between the slabs and base can be simulated. Improvements have been made to the user interface, including easier load creation, user-specified mesh refinement, and expanded visualization capabilities. These new features are detailed, and the concepts behind the implementation of EverFE2.2 are explained. In addition, the results of two parametric studies are reported. The first study considers the effects of dowel locking and slab-base shear transfer and demonstrates that these factors can significantly affect the stresses in slabs subjected to both uniform shrinkage and thermal gradients. The second study examines transverse joint mislocation and dowel looseness on joint load transfer. As expected, joint load transfer is greatly reduced by dowel looseness. However, while transverse joint mislocation can significantly reduce peak dowel shears, it has relatively little effect on total load transferred across the joint for the models considered.

A novel application of the principles of fracture mechanics combined with multilayered elastic theory is used to obtain the design stresses midway between the transverse joints at the bottom of the longitudinal edge of rigid pavements and for corner loading of slabs without dowels. The thermal curl stresses and deflection for slabs that are curled up, with and without vehicular loading, are also determined. The basic idea is to treat a joint with no load transfer, as a crack in a continuously supported plate on an elastic foundation. The deflection and stresses caused by the joint are determined by fracture mechanics, and those for the continuous pavement are determined by the CHEVRON multilayered elastic computer program. The total deflection and stresses are then obtained by superposition. The deflection and stresses so determined are compared with the Westergaard theoretical solutions, the results of finite-element programs, and experimental data from the American Association of State Highway Officials Road Test, showing good agreement.

To evaluate curling stresses in concrete pavements requires the input of a temperature differential or even a temperature distribution between the top and bottom of slabs. However, the slab temperature fluctuates throughout a day with many weather factors, such as air temperature, sunshine, clouds, and rain. It is still controversial about which measure during a day is the most appropriate input for curling analysis. The stress model adopted in this study to estimate pavement damage was developed with three-dimensional (3D) finite-element analysis. Field temperature measurements during different times of a day at 14 sites in the United States were input to calculate pavement compound stresses due to curling and wheel loads. By introducing fatigue hypothesis, an algorithm was developed to obtain "equivalent damages" and "effective temperature differential." The calculated effective temperature differentials were further correlated with local climate data.

Ternary blend concrete with reclaimed asphalt pavement as an aggregate in two-lift concrete pavement

- R Bentsen
- W A Vavrik
- J R Roesler
- S L Gillen

Bentsen, R., Vavrik, W. A., Roesler, J. R., & Gillen, S. L. (2003). Ternary blend concrete with reclaimed
asphalt pavement as an aggregate in two-lift concrete pavement. Proceedings of the 2013 International
Concrete Sustainability Conference, 6-8.

Reinforced concrete pavement. Wire Reinforcement

- R D Bradbury

Bradbury, R. D. (1938). Reinforced concrete pavement. Wire Reinforcement, 1-190.

Two-lift Portland cement concrete pavements to meet public needs

- J K Cable
- D P Frentress
- J A Williams

Cable, J. K., Frentress, D. P., & Williams, J. A. (2004). Two-lift Portland cement concrete pavements to
meet public needs. FHWA, U.S. Department of Transportation.

Dynamic analysis of rigid pavements with different subgrade-support models

- K Chatti
- T Kim

Chatti, K., & Kim, T. (2001). Dynamic analysis of rigid pavements with different subgrade-support models. Proc. of 7th International Conference on Concrete Pavements, International Society for Concrete
Pavements, Orlando, FL, 165-179.

Feasibility study of two-lift concrete paving

- J Hu
- D W Fowler
- M S Siddiqui
- D P Whitney

Hu, J., Fowler, D. W., Siddiqui, M. S., & Whitney, D. P. (2014). Feasibility study of two-lift concrete paving
(Technical Report No. FHWA/TX-14/0-6749-1). FHWA, U.S. Department of Transportation.

Finite element analysis of rigid pavements with partial subgrade contact

- Y H Huang
- S T Wang

Huang, Y. H., & Wang, S. T. (1974). Finite element analysis of rigid pavements with partial subgrade
contact. Transportation Research Record, TRB, National Research Council, 485, 39-54.

Construction of a cement concrete pavement in a Hilly Terrain in India

- R K Jain
- S Mirtunjay
- B B Pandey
- K Jwalendra

Jain, R. K., Mirtunjay, S., Pandey, B. B., & Jwalendra, K. (2016). Construction of a cement concrete pavement in a Hilly Terrain in India. 11th International conference on Concrete pavements, San Antonio,
TX, 252-256.

Investigation on temperature and friction stresses in bonded cement concrete pavement (Doctoral dissertation

- V V Subramanian

Subramanian, V. V. (1964). Investigation on temperature and friction stresses in bonded cement concrete
pavement (Doctoral dissertation, PhD thesis). Transportation Engineering Section, Civil Engineering
Department, IIT Kharagpur.

Two lift paving: An overview. Two-Lift Concrete Paving Workshop

- P Taylor

Taylor, P. (2013). Two lift paving: An overview. Two-Lift Concrete Paving Workshop.

Temperature variations and consequent stresses produced by daily and seasonal temperature cycles in concrete slabs

- J Thomlinson

Thomlinson, J. (1940). Temperature variations and consequent stresses produced by daily and seasonal
temperature cycles in concrete slabs. Concrete Construction Engineering, 35(6), 298-307.

Analysis of stresses in concrete pavement due to variations of temperature

- H M Westergaard

Westergaard, H. M. (1926a). Analysis of stresses in concrete pavement due to variations of temperature.
Highway Research Board, 6, 201-215.

Computation of stresses in concrete roads

- H M Westergaard

Westergaard, H. M. (1926b). Computation of stresses in concrete roads. HRB, National Research Council,
5(1), 90-112.