Contraction Joints Research Articles

СВІТОВА ПРАКТИКА ПРОЄКТУВАННЯ БЕТОННОГО ПОКРИТТЯ СТОЯНОК ВЕЛИКОВАГОВИХ ТРАНСПОРТНИХ ЗАСОБІВ І ЗОН КАНАЛІЗОВАНОГО ТА МАНЕВРОВОГО РУХУ

Introduction. The introduction to the paper emphasizes the performance of pavements for the traffic areas of channelized/maneuvering traffic zones and heavy vehicles parking lots and highlights the advantages of concrete pavements for the said objects. Problem statement. The issues of the paper concern the design of various types of concrete pavements for the traffic areas of channelized/maneuvering traffic zones and heavy vehicles parking lots. Purpose. The goal of the paper is to compare the main provisions of the designated concrete pavements design in terms of various types of the monolithic pavement concrete slabs, and usage of types of concrete which differ in their laydown methods, and also regarding various principles of joints construction with an accent made on the contraction joints. Results. The main principles of the said concrete pavements designing were reviewed through separation the input design data such as the geotechnical information, the parameters of loading, the pavement service life and the characteristics of the material. The pavement design regarding the requirements for the subgrade/subbase parameters was analyzed more detailed concerning the appointment of the pavement layers thicknesses to reach the required bearing capacity in terms of a modulus of subgrade reaction.

Seismic Fragility Analysis of Arch Dam Based on IDA and ETA Methods

In the assessment of the seismic performance of ultrahigh‐arch dams, challenges such as complex structural models, extensive degrees of freedom, and extended computation times are commonly encountered. Consequently, there is a pressing need to develop a more streamlined and effective approach for investigating the seismic behavior of ultrahigh‐arch dams. The endurance time method, a novel approach in seismic analysis, is increasingly favored for the dynamic analysis of large structures. In this study, the dynamic damage characteristics of an ultrahigh‐arch dam are analyzed based on the endurance time method, and the seismic fragility analysis is evaluated. Utilizing a case study of an ultrahigh‐arch dam in southwest China, a comprehensive three‐dimensional nonlinear model encompassing dam, bedrock, and water interactions is developed. This model incorporates considerations of dam and bedrock damage, cracking, dynamic behavior of contraction joints, and the interaction between the dam and reservoir water. The nonlinear least‐squares function is used to generate three endurance time acceleration functions (ETAFs) based on the response spectra of the hydraulic structure seismic design standard. The dynamic analysis of the above model is carried out by using the endurance time method and the incremental dynamic analysis (IDA) method. The results indicate that the endurance time method can well reflect the fragility of ultrahigh‐arch dams under different intensities of ground motions, with significant computational efficiency.

Effect of attached outlets on the dynamic response of arch dams

Attached outlets are integral components of arch dams to discharge flood. However, they are usually neglected in the current seismic analysis of arch dams for simplicity. This paper aims to analyze the effect of attached outlets on the nonlinear seismic response of arch dams. For this purpose, a 235 m high arch dam is analyzed as a case study. The results indicate that the effect of attached outlets on the seismic response of arch dams depends on the ground motion intensity. For the ground motions with a low peak ground acceleration (PGA), the effect of attached outlets on the concrete damage is slight and local, which is consistent with the existing perception. However, as the ground motion intensity increases, their effect extends to the entire dam body. In contrast, the influence of attached outlets on the joint opening is typically observed at the middle contraction joints. Furthermore, the model analysis demonstrates that the inertia effect of attached structures is the primary contribution to these phenomena. Finally, a simplified simulation approach is used for incorporating the influence of attached outlets by coalescing the mass to the dam surface.

Nonlinear data-driven zero-thickness joint element for concrete dam shear keys

Shear keys have been designed into the contraction joints of many concrete gravity dams to provide interlocking and shear transfer between adjacent monoliths. Their shear transferring capacity is usually estimated as the friction and cohesion that can be mobilized across a 2D plane located at the base of the keys. Once the shear stress in the contraction joint exceeds its estimated shear capacity, the shear keys are typically considered failed, and the joint may subsequently only transfer shear through concrete-concrete friction. This behaviour is often simulated in practice by placing tiebreak contact formulations along contraction joints. However, the nonlinear response and potential residual strength of the keys are usually ignored. In this paper, a novel nonlinear zero-thickness joint element named Macro Shear Key Joint Element (MSKJE) is proposed to simulate the response of a detailed shear key while capturing its nonlinear behaviour. A detailed geometrical numerical model of shear keys using a concrete Continuous Surface Cap Model (CSCM) is first validated against experimental data. Then, a parametric analysis of the number of keys in the joint, confinement pressure, initial opening and lateral boundary condition is performed using the validated detailed shear key numerical models. The stress-displacement responses obtained from the parametric analysis are used to calibrate the proposed MSKJE. At the local shear key scale, the MSKJE models present a very similar stress-displacement response compared to the detailed geometrical key models in terms of stiffness, maximum shear capacity, residual strength and nonlinear softening. At the global dam scale, the MSKJE presents a somewhat similar behaviour to the conventional tiebreak formulations. However, the advantages of the MSKJE over the tiebreak contact include its capability to simulate the nonlinear softening of shear keys, and residual sliding displacement, and, once calibrated, it is not necessary to estimate the shear keys capacity a priori.

Underwater Explosion Resistance Performance of an Old Gravity Dam without Good Longitudinal-Joint Connection Integrity: Coupled Acoustic-Structural Analysis

A gravity dam monolith bounded by the transverse contraction joints on both sides is usually recognized as an independent element in various dynamic analyses. However, in most cases a gravity dam monolith is actually subdivided by longitudinal joints for mass concrete construction requirements. Previous studies of gravity dams subjected to underwater explosion (UNDEX) shock loadings have not dealt with the longitudinal-joint issue in much detail. In this work, a numerical simulation of the dynamic response of an old gravity dam without good longitudinal-joint connection integrity in an UNDEX event is performed. The coupled acoustic-structural analysis procedure with ABAQUS/Explicit is employed. The reliability of the procedure is validated by numerical simulations of two UNDEX impact tests in the literature. Nine calculation cases are considered to compare different responses of the dam with different connection states between monolith sections and underwater detonation depths. The results of this numerical investigation show that the longitudinal joints play an important role in the UNDEX response of the dam. The longitudinal joints greatly weaken the flexural rigidity of the dam and make the dam damaged in a piecemeal manner. This study adds to the rapidly expanding field of the UNDEX resistance performance evaluation of gravity dams by accounting more for the longitudinal-joint issue.

Seismic damage characteristics of high arch dams under oblique incidence of SV waves

This study investigates the seismic damage characteristics of high arch dams considering the oblique incidence of seismic waves. Based on the dynamic implicit finite element method, a viscous-spring artificial boundary is applied to consider radiation damping of the infinite foundation, the seismic wave input is converted into an equivalent nodal force of the artificial boundary, and the equivalent nodal loads of the wave input under oblique incidence of the SV wave is deduced. Taking JP Ⅰ arch dam as an example, combined with the concrete damaged plasticity (CDP) model, the nonlinear dynamic response of the dam under 25° oblique incidence of the SV wave is conducted considering the geometrical nonlinearity of contraction joints and the dynamic mechanical properties of concrete materials. Based on the incremental dynamic analysis (IDA) method, the relative displacement and transverse joint opening are selected as the damage measures for fragility analysis of the arch dam. According to the damage distribution from the analysis of a large number of seismic time-history responses, the damage levels of the arch dam are classified. Three limit states of slight damage, moderate damage and severe damage are proposed for the arch dam. The average responses of the 10 earthquakes are considered as the limit values to quantitatively describe the damage of the arch dam. By fitting the results of incremental dynamic analysis, the seismic probabilistic demand model and seismic fragility curves for the two damage measures to predict the probability of the arch dam reaching damage levels under different seismic actions have been established. The fragility curve shows that the probability of severe damage is almost zero under the maximum design earthquake (PGA = 0.1971 g) and less than 5% under the maximum credible earthquake (PGA = 0.2299 g). It is concluded that JP Ⅰ arch dam has a high degree of safety redundancy and fully satisfies the “two levels” design requirements.

Blast Performance and Damage Evaluation of High Arch Dams Subjected to Far-Field Underwater Explosions: Consideration of Joints

The blast performance of 300-m-high arch dams is an important subject which has been studied widely over the years. An arch dam is convex on the upstream face, and the load is transmitted along the arch axis to the abutments at the ends of the dam. However, the integrity of arch dams is affected by the transverse contraction joints. The blast resistance performance of a 300-m-high arch dam subjected to far-field underwater explosion was investigated considering contraction joints. The acoustic–structural method was employed to model the underwater explosion loads and the interactions among the dam–reservoir–foundation system. To verify the reliability of the acoustic–structural method, a 1∶200-scale model of an arch dam subjected to far-field underwater explosion was tested. A zero-thickness cohesive element was employed to model the mechanical behavior of contraction joints with grouting. Nonlinear dynamic response and damage progress of the high arch dam with transverse contraction joints to the far-field underwater explosion were investigated in terms of peak displacement, velocity, and damage modes. The tensile damage mechanism of the arch dam subjected to the far-field underwater explosion was discussed. The damage modes and deformation mechanism of high arch dams at the different positions of initiation point were presented. A damage index based on the damaged area in the downstream face and foundation face is proposed to evaluate the blast performance of high arch dams subjected to far-field underwater explosions. The results show that the contraction joints have a certain influence on the nonlinear dynamic and damage modes of high arch dams subjected to the far-field underwater explosion. The damage is larger with explosive charges near the one-quarter arch ring in the weak stiffness bank due to the asymmetry of the arch dam.

Towards a Better Understanding of Concrete Arch Dam Behavior during the First Filling of the Reservoir

During the first filling, the reservoir is gradually raised in multiple stages. At each stage, the filling is paused to allow adequate time for monitoring and evaluating the performance of the dam and its foundation. The analysis of the monitored behavior and assessment of security conditions is performed by comparing the values measured by the monitoring system installed in the dam with the values predicted by numerical models representing the structural behavior, the material properties, and the loads. This article addresses the main aspects related to the safety control of concrete arch dams during the first filling of the reservoir. Special attention is given to the nonlinear behavior induced by the opening/closing of the contraction joints. An example of numerical simulation of the behavior of an arch dam during the first filling of the reservoir is also presented. The validation of the computed temperatures, the induced displacements and the induced stresses was performed by comparison with the values measured with the monitoring system installed in the dam.

Use of ultrasonic tomography for the assessment of critical aspects of doweled joints in concrete pavements

The critical (design) parameters to be controlled for concrete pavements construction, in addition to the concrete strength, are slab`s thicknesses and doweled bars position at contraction joints, as they affect hugely structural performance, and, if not properly built may cause early ruptures. Construction compliance of such parameters is nowadays assessed through nondestructive techniques (NDT), such as ultrasonic low-frequency waves. Alignments of inserted doweled bars at contraction joints are analyzed herein for actual slabs as well as how thickness affects such position. Tests were carried out over an airport hangar apron after it has been built. Twenty-five concrete slabs were assessed using ultrasonic tomography allowing to verify disconformities of thicknesses and bars vertical and horizontal misalignments, with fair accuracy on measuring deviation angles of bars.

Assessing Premature Cracks in Urban Concrete Pavements

There are many urban jointed plain concrete pavements (JPCPs) constructed annually in the U.S. by counties, cities, and municipalities, which typically use state department of transportation standards but are not part of a systematic check to determine if design, construction, and performance are meeting expectations. A field evaluation survey with nondestructive testing was initiated on urban JPCPs throughout Illinois to assess performance and identify any deficiencies in design and construction. A total of 67 JPCPs were selected based on their design features and age. A significant number of sections (57%) were selected because they exhibited some level of premature cracking. Based on the field investigation, multiple mechanisms were proposed to explain the premature cracks. Many transverse and longitudinal cracks observed had excessive slab lengths or widths that were inconsistent with best slab geometry practices. There was no link established between observed cracking and the slab-base frictional restraint or the concrete mixture. For some sections, ultrasonic tests over the contraction joints determined certain joints had not activated and likely contributed to transverse cracks in adjacent slabs. Lack of dowel bar lubrication at the transverse contraction joints was also a plausible mechanism that restrained joint movements and produced excessive tensile stresses in the slab, which led to premature transverse cracks. The mechanisms leading to almost all observed premature cracks for these urban JPCPs were attributed to not adhering to existing state standards (slab geometry limits) and specifications (saw-cut timing/depth and dowel lubrication) during the pavement design and construction phases.

Injection of discontinuities in concrete dams with cement-based grouts

ABSTRACT Injecting discontinuities is a recurrent procedure for the rehabilitation of concrete hydraulic structures, namely repairing cracked dam bodies and deteriorated lift and contraction joints. Within this scope, a relatively detailed description of the most important cement injection grouts features is presented, including the main advantages and drawbacks compared to alternatives. The cement-based grouts are among the most utilised materials in these contexts. Economic and environmental related aspects are among the main advantages of cement-based grouts, although some technical features of these grouting materials are also favourable. The equipment utilised for the preparation and for the application of cementitious grouts is also mentioned. This document also addresses aspects related to the assessment of concrete dams’ stability, the preparatory works, the common methodologies and the standard precautions to have into account when planning a rehabilitation operation involving cement grouting for filling cracks or repairing lift or contraction joints in these massive structures. A list of successful rehabilitation case histories is provided, including a short description of the anomalies and their causes, as well as a summary of the main repair measures adopted for each situation.

Setting time in Roller-Compacted Concrete (RCC)

The principal differences of RCC from conventional concrete pavements are workability, rheology, paste content, and compactive effort. RCC pavements obtain significant strength during compaction and, therefore, can be opened to traffic in less time than conventional concrete pavements. For both types of concrete, there are methods to evaluate workability in the fresh state, e.g., slump and Vebe test. However, no standard method is available for either concrete pavement type for evaluating setting time in-situ. Construction activities such as tining/texturing, curing membrane, and sawing of contraction joints are related to the concrete setting time. A recently developed technique for setting time of conventional mortar and concrete with fully contactless ultrasound has shown promising results with higher paste content mixtures. This recently proposed method monitors the initiation time of leaky Rayleigh waves (LR-wave) signals in time and space over the conventional concrete surface. The objective of this study is to determine the setting time in RCC pavements which has significantly lower paste volume and higher aggregate content. Preliminary results have shown that the setting time of an RCC mixture with overfilled paste can be successfully determined. Additional tests on a wider range of RCC mixture constituents and proportions, e.g., lower aggregate void and paste contents, are being conducted to evaluate the limitations of this contactless sensing method and necessary adjustments. Reliable set time determination in RCC pavements can improve QC/QA practices and indicate repeatable triggers for other construction activities like sawing contraction joints.

Three-dimensional failure envelope of concrete dam shear keys

Shear keys provide interlocking mechanisms along the vertical contraction joints of many concrete gravity dams. The shear key ultimate shear capacity is typically estimated as a function of the friction and cohesion that could be mobilised across a 2D shear plane located at the base of the key when subjected to a normal confinement pressure, P. A two-dimensional response of dam monoliths and shear keys shearing-off at their bases, is assumed. However, evidence of 3D interlocking behaviour between dam monoliths and the possibility of different key failure mechanisms involving interacting axial, P, shear, V, moment, M, and torsion, T, indicates that typical empirical formulations could significantly overestimate the actual shear key capacity under floods and seismic loadings. This paper presents an evaluation of the load–displacement response of shear keys subjected to multiaxial loading via nonlinear finite element analyses. A concrete “Continuous Surface Cap Model” (CSCM), available in the computer program LS-Dyna, is first shown to best capture the experimental shear keys' ultimate and residual shear capacity responses among five constitutive models. The effects of the tensile strength, fracture energy, confinement pressure, friction coefficient, initial opening, and dilation conditions on the load–displacement response of keys are investigated. Failure envelopes considering the key multiaxial shear capacity with confinement pressure, P, moment, M, and torsion, T, are developed. The ratios between moment and shear, M/V, and torsion and shear, T/V, control the failure mechanism. Increasing these ratios significantly reduce the ultimate shear capacity.

Long-Term Thermal Stress Analysis and Optimization of Contraction Joint Distance of Concrete Gravity Dams

Results of the conducted research aiming to demonstrate the methodology of optimization of dam monolith length (distance between contraction joints), through monitoring the thermal tensile stresses during construction and service life of a concrete gravity dam that is built using the block method, are presented in this paper. A 3D space–time numerical model for phased thermal stress analysis is employed in a large concrete gravity dam case study. For the adopted block dimensions, schedule, and dynamics of construction and material parameters, the thermal stress analysis is conducted, taking into account the following: thermal physical properties of the material, the cement hydration process, heat exchange with the external environment and the reservoir, and self-weight of the structure. The main advantage of the proposed methodology is the possibility of controlling the cracks resulting from thermal tensile stresses in the monolith of a concrete gravity dam, by optimizing the monolith’s length to minimize the zones in which the tensile capacity of concrete is exceeded. The results obtained from the temperature field analysis show that the maximum temperature increase in the dam’s body results from the cement hydration process in combination with summer air temperatures in the construction phase. The aforementioned factors account for the increase in temperature of up to 45.0 °C, while during winter cooling of the structure occurs due to lower temperatures, especially in the surface zones. The results of the stress field analysis show that the extreme values of thermal tensile stresses are present in the process of a sudden or gradual cooling of the concrete when shrinkage occurs. Finally, it is shown that the reduction of the monolith length by 5.0 m (from 20.0 m to 15.0 m) results in a decrease in the extreme thermal tensile stress values by an average of 0.70 MPa (up to 12.0%) in winter and an average of 1.10 MPa (up to 20.0%) in summer; while for the entirety of the analyzed time period, results in a decrease in the extreme thermal tensile stress values by an average of 16.0% (0.93 MPa).

CONSTRUCTION TECHNIQUES FOR CRACK CONTROL OF CAST-IN-PLACE CONCRETE SLABS AND WALLS

The paper presents recommended construction techniques for crack control of cast-inplace concrete slabs and walls. The crack control in this paper refers to controlling or preventing crack formation during the placing, stiffening and shrinking of fresh concrete. These cracks are influenced by means and methods of construction as opposed to structural cracks due to imposed loads. The techniques affecting construction crack formation involve details regarding volume and length of concrete pour, casting sequence, concrete curing and mix design. These strategies are related directly to concrete joints. Various joint types: saw cut, contraction, expansion and construction joints are discussed. The paper emphasizes that saw cut joint is a dummy or fake joint and has no use for crack control. The suggested techniques recommend the use of full-face construction joints to limit the length of each pour segment to 5m to 10m maximum, followed by water curing of concrete for a minimum elapsed time before placing the adjacent pour. For large projects, several alternate slab panels may be poured simultaneously. The closure pours between the first pour panels can then be cast after the minimum elapsed time. It is noted that continuous wet water curing of concrete is recommended over membrane curing method for better quality control. Lastly, concrete mix which includes 15% to 20% of fly ash is recommended for lower heat of hydration and concrete shrinkage. Several proven examples of successful projects using the recommended techniques, within the past 50 years, are given to confirm the effectiveness of the methods.

CONSTRUCTION TECHNIQUES FOR CRACK CONTROL OF CAST-IN-PLACE CONCRETE SLABS AND WALLS

The paper presents recommended construction techniques for crack control of cast-inplace concrete slabs and walls. The crack control in this paper refers to controlling or preventing crack formation during the placing, stiffening and shrinking of fresh concrete. These cracks are influenced by means and methods of construction as opposed to structural cracks due to imposed loads. The techniques affecting construction crack formation involve details regarding volume and length of concrete pour, casting sequence, concrete curing and mix design. These strategies are related directly to concrete joints. Various joint types: saw cut, contraction, expansion and construction joints are discussed. The paper emphasizes that saw cut joint is a dummy or fake joint and has no use for crack control. The suggested techniques recommend the use of full-face construction joints to limit the length of each pour segment to 5m to 10m maximum, followed by water curing of concrete for a minimum elapsed time before placing the adjacent pour. For large projects, several alternate slab panels may be poured simultaneously. The closure pours between the first pour panels can then be cast after the minimum elapsed time. It is noted that continuous wet water curing of concrete is recommended over membrane curing method for better quality control. Lastly, concrete mix which includes 15% to 20% of fly ash is recommended for lower heat of hydration and concrete shrinkage. Several proven examples of successful projects using the recommended techniques, within the past 50 years, are given to confirm the effectiveness of the methods.

Quantifying the effect of ground-motion nonstationarity on the nonlinear dynamic responses of an ultra-high arch dam

Nonstationarity of a ground-motion time history refers to the changing frequency features over time. The frequency nonstationarity can greatly affect nonlinear structural responses, but is difficult to be captured realistically by current stochastic simulation methods. In this study, the ECSC-rho method is developed to generate synthetic earthquake ground motions through wavelet-packet characterization and optimization. Time and frequency properties of acceleration time histories are characterized using wavelet-packet analysis. The correlation between wavelet-packet coefficients in time and frequency domains is used as a simple proxy to represent nonstationarity in an acceleration time history. The basic idea is to adjust the wavelet-packet coefficients of a seed motion in both time and frequency domains to reconstruct an accelerogram, such that it matches a target spectrum, Arias intensity and nonstationarity feature. Compared with existing spectrum-matching techniques, the ECSC-rho method has distinctive advantages in simulating ground motions with prescribed nonstationarity, response spectra and energy build-up processes. The performance of the proposed ECSC-rho method is systematically validated using an ultra-high arch dam model, which incorporates highly nonlinear dam responses such as the opening of contraction joints and cumulative concrete damage. Extensive numerical simulations will highlight the effects of ground-motion nonstationarity on nonlinear dam responses, and provide practical guidelines for using spectrally-matched synthetic motions in dynamic dam analysis.

Comparison of the Seismic Responses of an Arch Dam under Excitation from the Design Response Spectrum in the New and Old Chinese National Standards

The new Chinese national standard, Standard for the seismic design of hydraulic structures (GB51247-2018), has been published. Compared with the Specifications for the seismic design of hydraulic structures (SL203-1997), the standard design response spectrum curve was revised in the new national standard. In order to compare the seismic responses of an arch dam under excitation from the design response spectrum in the new and old standards, the dynamic calculation of a 240 m high arch dam is carried out by a three-dimensional finite element method. In the dynamic calculation, the B-differentiable equation is used to simulate the tension motion of arch dam contraction joints, and the multi-transmitting boundary method and the Westergaard added mass method are used to simulate the dam–infinite foundation and dam–reservoir interactions, respectively. The results show that the dynamic stress responses of the arch dam under excitation from the design response spectrum in the new standard are increased compared with those of the old standard. The seismic safety of an arch dam may decrease under excitation from the design response spectrum in the new standard. Thus, the seismic validation on built arch dams should be carried out by using the new standard when it is possible.

Pore Preservation and Failure Mechanism of Sinian Dengying Formation Carbonate Reservoirs: A Case Study of Two Ultradeep Wells in the Sichuan Basin, Western China

Despite being one of the most important factors in deep oil and gas exploration, the preservation mechanisms of ultradeep carbonate reservoirs remain poorly understood. This study performed thin-section, geochemistry, field emission scanning electron microscopy, fluid inclusion, and basin model analysis of samples from two boreholes over 8,000 m deep in the Sichuan Basin to determine the pore features and preservation mechanism of the Sinian (Ediacaran) Dengying Formation carbonate reservoirs. The reservoir of CS well #1 is characterised by pore diameters larger than a centimetre (average porosity 7.48%; permeability 0.8562 mD), and the pores are mainly filled with dolomite or bitumen. In contrast, the reservoir of MS well #1 is predominantly composed of micron-scale residual pores (average porosity 1.74%; permeability 0.0072 mD), and the pores are typically filled with dolomite, bitumen, and multistage quartz. The burial thermal histories suggest that both reservoirs were subjected to high pressure (i.e., pressure coefficient > 1.5 ) before the Late Cretaceous. However, the pressure coefficient of the reservoir of MS well #1 has decreased to less than 1.0 owing to strong structural adjustment this well since the Late Cretaceous, which allowed other ore-forming fluids to enter and fill the pores, resulting in further compaction of the pores. In contrast, the pressure coefficient of CS well #1 is 1.1–1.2, which effectively prevented other ore-forming fluids from entering and filling the pores. The findings show that the dynamic adjustment of the Dengying Formation palaeo-gas reservoir indirectly affects the preservation or failure of the reservoir. The occurrence and geometry of bitumen in the Dengying reservoir exhibit good consistency with the pressure changes in both boreholes. In particular, bitumen with an annular shape and contraction joints in reservoir pores is widespread in CS well #1, which is attributed to the continuous preservation of palaeo-gas fields. Conversely, bitumen with a broken particle shape is located among the epigenetic minerals widespread in MS well #1, which is attributed to failure and depletion of the palaeo-gas fields.

Evaluation of Load-Transfer Efficiency of Steel Mesh Reinforced Contraction Joints in Concrete Pavement: Accelerated Pavement Test and FE Analysis

Transverse contraction joints are by far the most common type of joint in jointed plain concrete pavements. Early loading of contraction joints can create a weakened vertical plane and later grow as a full-depth crack. In this study, load transfer efficiency (LTE) of steel mesh reinforced transverse contraction joints were studied at accelerated pavement tests (APT). 3D finite element (FE) model of jointed plain concrete pavement (JPCP) was developed to study deflections and crack propagation in just under the joint of the concrete pavement. The APT tests were focused on the LTE values before and after the crack initiation under the contraction joint region. Experiments were performed on three slabs in which two of these slabs were prepared without reinforcement and one of them was reinforced with steel mesh. Data generated by APT was used for verification of crack propagation modeling in the finite element analysis. Steel mesh reinforced slab gave the lowest vertical deflections (51μm) and highest LTE (91.56%). The LTE value in the reinforced slab after 25,000 passes was 13.63% higher than the average of unreinforced slabs. The findings suggest that the load transfer efficiency was found to be a complex parameter and should be interpreted together with average displacement values when contraction joints are evaluated at early traffic loadings.