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The 2016 Kaikoura earthquake resulted in shaking in excess of design level demands for buildings with periods of 1-2s at some locations in Wellington. This period range correlated to concrete moment frame buildings of 5-15 storeys, many of which had been built in Wellington since the early 1980s, and often with precast concrete floor units. The critical damage states used to assess buildings during the Wellington City Council Targeted Assessment Programme are described and examples of observed damage correlating to these damage states are presented. Varying degrees of beam hinging were observed, most of which are not expected to reduce the frame capacity significantly. Buildings exhibiting varying degrees of residual beam elongation were observed. Cases of significant beam elongation and associated support beam rotation resulted in damage to precast floor unit supports; in one case leading to loss of support for double-tee units. The deformation demands also resulted in damage to floor diaphragms, especially those with hollowcore floor units. Cracking in floor diaphragms was commonly concentrated in the corners of the building, but hollowcore damage was observed both at the corners and in other locations throughout several buildings. Transverse cracking of hollowcore floor units was identified as a particular concern. In some cases, transverse cracks occurred close to the support, as is consistent with previous research on hollowcore floor unit failure modes. However, transverse cracks were also observed further away from the support, which is more difficult to assess in terms of severity and residual capacity. Following the identification of typical damage, attention has shifted to assessment, repair, and retrofit strategies. Additional research may be required to determine the reduced capacity of cracked hollowcore floor units and verify commonly adopted repair and retrofit strategies.

This study predicted transverse cracking progression in laminates including 90° plies. The refined stress field (RSF) model, which takes into account thermal residual strain for plies including transverse cracks is formulated, and the energy release rate associated with transverse cracking is calculated using this model. For comparison, the energy release rate based on the continuum damage mechanics (CDM) model is formulated. Next, transverse cracking progression in CFRP cross-ply laminates including 90° plies is predicted based on both stress and energy criteria using the Monte Carlo method. The results indicated that the RSF model and the CDM model proposed in this study can predict the experiment results for the relationship between transverse crack density and ply strain in 90° ply. The models presented in this paper can be applied to an arbitrary laminate including 90° plies.

The coupled effect of transverse cracking and cyclic drying–wetting conditions on chloride penetration in concrete is explored in this paper. The transport mechanisms of chloride in cracked concrete subjected to drying–wetting cycles are described and simplified. An experimental investigation was conducted for sustained cracked concrete beams and the results are reported here. It is found that the depth interval of the convection region in cracked concrete varies from approximately 10 to 20 mm, which is slightly greater than that found in sound concrete. Also, it increases with the increase in crack width and decreases with the increase in fly ash content. At the cracked sections, the speed of chloride penetration is increased by the presence of cracks. It is shown that the modified diffusion model is still practicable for describing the chloride distribution in transversely cracked concrete when the crack width is within a range close to 0·30 mm. Finally, a regressive relationship between equivalent chloride diffusion coefficient, DCleq, and crack width, wcr, is proposed with a quadratic function of crack effect.

International audience; Multi-cracking of brittle thin layers and coating is a phenomenon difficult to model especially because of the large number of cracks that may occur. It is overcome herein by conducting calculations, not on the whole structure, but only on a simplified cell that is representative of the structure by periodic duplication. The coupled criterion is applied within this representative cell (RC) and allows to predict the crack density under an increasing applied load, the length of the RC being a variable parameter of the model. Based on the simultaneous fulfilment of an energy and a stress conditions, it allows to take into account thin layers where the crack onset is energy driven and thicker layers where the stress condition governs the transverse cracking. Results are in a good agreement with various experiments found in the literature, conducted on cross-ply laminates and coated substrates.

The characterisation of fatigue damage evolution in constrained glass fibre reinforced plastic off-axis laminates is presented. A newly developed imaging technique known as Automatic Crack Counting (ACC) is used to quantify the off-axis crack state in constant amplitude (CA) and variable amplitude (VA) block loading tension-tension fatigue tests and constant amplitude compression-tension tests. The quantified crack states are analysed by combining the newly developed ACC method with a data mining approach and applying these to large data sets obtained during fatigue tests. It is shown that for a constant stress level, the stochastic nature of off-axis crack initiation and crack growth is accurately modelled by the Weibull distribution, with the distribution parameters being efficiently derived using the developed approach. The data-rich characterisation provides new insight in the crack density evolution process for VA and C-T loading, as well as derived Weibull distribution parameters in combination with the classical S-N curves and Paris’ Law relationship. Hence, providing an improved approach that includes the stochastic and deterministic information for physically based modelling of crack density evolution for fatigue loading.

This paper presents a numerical study evaluating the influence of nonlinear material behavior on the stiffness reduction due to inter-fiber cracks. It is shown that the relation between crack density and damage variables changes as the load level increases. A three-dimensional nonlinear material model is used in a representative volume element study to accurately calculate the local stress distribution around cracks. The studies show that as the load increases the stress recovers to the far-field level within a shorter distance, and consequently the plastic deformation causes a decrease in the crack-induced stiffness reduction. To provide damage variables for a coupled elastoplastic-damage material approach at the homogenized ply level, the results of a systematic representative volume element study are used for interpolation. For verification, the response curves of several laminates influenced by inter-fiber cracks are simulated and compared to experimental results. The presented procedure enables the constitutive laminate response under large deformations to be accurately predicted.

Cracking has become a primary mode of distress in recent years that frequently drives the need for rehabilitation of asphalt pavements. Meanwhile, asphalt mix designs are becoming more and more complex with the increasing uses of recycled materials, recycling agents, binder additives/modifiers, and multiple warm mix asphalt technologies. Thus, there is an urgent need to identify reliable cracking tests that can be used for routine mix design to eliminate brittle mixes. This paper critically reviewed cracking mechanisms and laboratory tests. A total of 12 cracking tests were discussed at a cracking test workshop held as part of the National Cooperative Highway Research Program Project 9-57. Seven cracking tests were selected for further laboratory evaluation and field validation. Four of the simpler cracking tests from the seven were evaluated in this paper, these being the Texas Overlay Test (OT), Disk-shaped Compact Tension (DCT) test, Semi-Circular Bend test from the Louisiana Transportation Research Ce...

The purpose of this paper is to investigate the moisture absorption effect on the stress distribution of the cross-ply laminates with transverse matrix cracks. Two analytical models were used to evaluate the stress distribution, Shear Lag and the variational approach. The results show that a complete parabolic variation of displacement gives a good approximation of the stress distribution compared to the finite element analysis. Furthermore, the cracked cross ply laminate is submitted different temperature and moisture concentration distribution. The predicted model shows that moisture absorption has a significant effect on the stress distribution especially at the higher crack density.

High quality predictive program provides an alternative to assess the long-term performance of asphalt pavements if well-evaluated based on field performance. The asphalt pavement performance models embedded in the Pavement ME Design program were developed based on hot mix asphalt (HMA) pavements, and the predictive quality varies depending on specific conditions. The applicability of the Pavement ME Design program as well as the embedded performance models to warm mix asphalt (WMA) pavements is even unclear. In addition, the ability of the Pavement ME Design program in differentiating HMA and WMA performance, if any, has not been evaluated. Therefore, the objectives of this study are to determine the predictive quality of the Pavement ME Design program for the field performance of WMA pavements, and further to evaluate the capability of Pavement ME Design program in detecting performance difference between HMA and WMA pavements if there is any. A total of 43 asphalt pavements (both HMA and WMA) from 16 projects were evaluated based on their field measured and predicted performance, in terms of rutting, transverse cracking and top-down longitudinal cracking. Results indicate that (1) The Pavement ME Design program can predict the field rut depth well for HMA and WMA pavements, in terms of both numerical values and rankings. However, the software in general over-estimates the field rut depth; (2) The Pavement ME Design program cannot predict field transverse cracking or field longitudinal cracking correctly irrespective of pavement type; (3) The results suggest that the effect of moisture should be considered in the Pavement ME cracking models for both HMA and WMA pavements, and (4) Overall, the predictive quality of the Pavement ME Design program for HMA and WMA is similar, either in good or poor prediction results. The WMA technology does not fundamentally alter the behavior of asphalt materials in pavement application. We suggest treating WMA similarly as HMA while applying the Pavement ME Design program for performance prediction. However, the corresponding WMA material properties should be used as input values.

During the ice-cover period, initial ice-cover breakup precedes ice-jam flood events. Hence, it is important that breakup processes are well understood in order to be better prepared for ice-jam flood forecasting. Being able to predict ice-cover breakup provides an indication when ice-jam flood forecasting should commence. This chapter explains ice-cover breakup processes that can lead to ice jamming and ice-jam flooding. Spreadsheet exercises are provided to help reinforce the concepts of these processes and to help the reader build up a repertoire of tools that can be used to estimate backwater levels from ice jams. These tools will be extended in later chapters to help develop a simple ice-jam flood forecasting system.

Transverse cracking is probably the first and most dominant mode of damage in composite materials. In this paper, transverse cracking of cross-ply [02/90n]s (n = 2,3,4) laminates under uniaxial tension load was studied by means of experimental and numerical methods. In the numerical simulations, a simplified computational strategy only focusing on the damage of the resin was proposed and the mechanical response of the cracking cross-ply laminates was studied by finite element analysis of multi-scale representative volume elements (RVEs). In the RVEs, the longitudinal 0&deg, plies were represented by macro-scale, homogeneous, orthotropic elastic solids while the 90&deg, plies were modeled by the discrete fibers and the surrounding matrix resin in micro-scale. Based on researching the critical longitudinal mechanical strain &epsilon, x which initiates the cracks, the in-situ transverse ply strength and the stiffness degradation of the transverse plies, the simplified computational strategy proposed was proven correct. In addition, the crack initiation is sensitive to residual stress. Higher process-induced residual stress levels are dangerous to laminates, leading to early crack initiation.

© 2018 Elsevier Ltd Voids are an important type of manufacturing defects in fiber-reinforced composites. Matrix cracking is sensitive to the presence of voids. Although this cracking occurs at the ply scale, its dynamics is strongly affected by ply's microstructure, in particular, fiber distribution, fiber content, and the presence of voids. In the current study, a computational approach to simulate the influence of intra-laminar voids on cracking in composite laminates is developed. The approach combines finite element models of two scales: a micro-scale model, where the fibers and voids are modeled explicitly, and a meso-scale model, where the cracking phenomenon is captured on the ply scale. The micro-scale model, incorporating plasticity and damage in the matrix, provides input for the meso-scale model, which simulates the progressive cracking by means of the extended finite element method. The methodology is applied to investigate the effect of voids on the density of transverse cracks in cross-ply laminates in function of the quasi-static tensile load. Different sizes and contents of voids, which are chosen based on experimental micro-computed tomography data, are simulated. The numerical experiments show that the presence of voids leads to earlier start of the cracking, with the crack density evolution less sensitive to voids. ispartof: COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING vol:117 pages:180-192 status: published

International audience; The growth of fiber/matrix interface cracks (debonds) located on consecutive fibers along the through-the-thickness direction is studied in glass fiber-epoxy UD composites. Two different families of Representative Volume Elements (RVEs) are developed: the first implements the classic condition of coupling of the vertical displacements to model a unit cell repeating symmetrically along the vertical (through-the-thickness) direction; the second uses a novel set of boundary conditions, proposed here by the authors, to represent a unit cell repeating anti-symmetrically along the vertical direction. The model is analyzed in the context of Linear Elastic Fracture Mechanics (LEFM) and the Mode I and Mode II Energy Release Rate are evaluated to investigate crack growth. The calculation is performed using the Virtual Crack Closure Technique (VCCT) and the evaluation of the J-Integral in the framework of the Finite Element Method (FEM). It is found that Mode I dominated propagation is favored when debonds are located on the same sides of their respective fibers, while larger debond sizes can be achieved in Mode II dominated growth when they lie on the opposite sides. No effect is present when at least two fully bonded fibers are located between the partially debonded ones.

We evaluated rebar corrosions in a continuously reinforced concrete pavement (CRCP) in use for more than 30 years through field surveys. Ultrasonic shear-wave tomography analysis and concrete coring indicated that horizontal cracks occurred within approximately 300 mm from the transverse cracks in both sound and deteriorated parts. Longitudinal rebar corrosion was only observed within approximately 150 mm from the transverse cracks. X-ray computed tomography image analysis revealed that the loss of cross-sectional area in the rebar due to corrosion, which was the largest within 70 mm from the transverse cracks, was generally 15–22%, whereas the loss at a distance of greater than 70 mm from the transverse cracks was largely decreased to approximately ≤ 4%. The chloride content in concrete at the rebar depth did not exceed the critical value, except in areas adjacent to transverse cracks. Our results suggest that the effect of rebar corrosion on long-term CRCP deterioration is insignificant.

The performance of jointed plain concrete pavement is affected by various design parameters including mechanical and thermal properties of concrete. Out of these, coefficient of thermal expansion, elastic modulus and modulus of rupture are a few important ones and to evaluate the effects of these material properties on pavement performance, simulations were carried out in MEPDG. All other design parameters such as traffic, design life, climate and road bed soil conditions were considered as constant and pavement performance was evaluated. The simulation results appreciated that with an increase in coefficient of thermal expansion of concrete, the pavement performance was adversely affected. In addition, with an increase in elastic modulus and modulus of rupture values of concrete, the strength of concrete increases and resultantly an improved pavement performance was obtained. It became evident that these material parameters should be carefully considered while designing a rigid pavement. Keywords: Coefficient of thermal expansion (CTE), Modulus of rupture (MOR), Jointed plain concrete pavement (JPCP), Mechanistic empirical pavement design guide (MEPDG), Transverse cracking, Joint faulting

A novel nonlocal discrete model is proposed in this paper to study the deformation and failure behaviors of cross-ply laminated composite plate under static or quasi-static mechanical loadings. Different from existing numerical approaches, the proposed model accounts for the material anisotropy at both constitutive and structural level. To achieve this purpose, the proposed model rotates the underlying topological structure, rather than transforming the material’s tangent stiffness matrix as in the continuum-based simulations. Thus, different failure behaviors can be modeled as the natural outcome of the breakage of connecting springs. The proposed model is verified and validated by comparing the simulation results with analytical solution and experimental observations from open literature.

The long-term performance of asphalt concrete (AC) overlays using mixtures containing reclaimed asphalt pavements (RAP) is compared with the performance of overlays using virgin mixtures. Data from 18 sites of the long-term pavement performance (LTPP) program are used for analysis. Each site consists of 8 side-by-side experimental sections that vary in overlay thickness and pre-overlay treatment method. The selected performance indicators include fatigue cracking, longitudinal cracking, transverse cracking, rutting, and roughness. Explorative data analysis, non-parametric survival analysis, and pair- t tests are used to compare possible performance differences. The analysis results suggest that there are interactive effects between the use of RAP-containing mixtures, overlay thickness, and pre-overlay treatment method. With relatively thin (51 mm) overlay and minimal pre-overlay treatment, undesirable performance of RAP-containing mixtures is expected. Conversely, with relatively thick (127 mm) overlay and intensive pre-overlay treatment, RAP-containing mixtures outperform virgin mixtures in rutting and roughness, without inducing additional cracking-related distresses. The field performance of RAP-containing mixtures is believed to be driven by their fundamental properties, i.e., the reduced cracking resistance and increased stiffness.

The first damage mode to appear in continuous fibre-reinforced composite laminates subjected to in-plane loading is usually transverse cracking, i.e. matrix cracking in the off-axis plies of the laminate. Since the density of transverse cracks has a great influence on the subsequent failure steps like delaminations, it is important to be able to predict it accurately. In this paper, the evolution of crack density with increasing external load is predicted using a combination of the Coupled Criterion of Finite Fracture Mechanics and the Equivalent Constraint Model.

A method for assessing the susceptibility of a weld to transverse cracking is proposed based on a newly designed test specimen featuring a transverse gap in the centre to control restraint and produce a large residual stress in the weld metal. Through FEM simulation of the effects of the weld bead length on the longitudinal residual tensile stress (σx) after welding, it is confirmed that the transverse gap can significantly increase σx after welding. Furthermore, with a fixed transverse gap length, σx increases monotonically with the length of the weld bead. Two different commercial weld wires were used to check the effectiveness of this method; the experimental results obtained indicate that the critical cracking length of the weld bead differs depending on the weld wire used. The critical length of the weld bead can therefore be used as an effective index of its susceptibility to transverse cracking.

With the growing awareness of sustainable construction practices and because warm-mix asphalt (WMA) is environmentally friendly, WMA is gaining popularity for pavement construction in the United States. Currently, it is generally believed that rutting and moisture damage are two major concerns for WMA pavements, but because WMA requires less aging, its cracking resistance is expected to be improved. One of the primary cracking distresses of concern is transverse cracking, which could be thermal cracking in asphalt pavement or reflective cracking in asphalt overlay caused by underlying thermal cracking. Thus, transverse cracking is another primary distress. This study investigated the long-term field transverse cracking of 28 pavement projects, including WMA pavements and corresponding hot-mix asphalt (HMA) control pavements across the United States, covering different climate zones, WMA technologies, service years, pavement structures, and traffic volume levels. Two distress surveys were conducted at an interval of 2 years, and the material properties of the asphalt mixtures and binders were determined with field cores and extracted binders. The long-term field performance of the WMA and HMA pavements were compared for transverse cracking. The study found that HMA and WMA pavements exhibited comparable transverse cracking. Fracture work density obtained from indirect tensile testing at 14°F was found to be the significant determinant for transverse cracking. Significant mix design parameters were identified that can affect the resistance of mixtures to transverse cracking and that can be employed to guide the development of a well-performing mix design.

Metal/ceramic composites with lamellar microstructures are a novel class of metal-matrix composites produced by infiltration of freeze-cast or ice-templated ceramic preforms with molten aluminium alloy. The cost-effectiveness of production and relatively high ceramic content make such composites attractive to a number of potential applications in the automotive, aerospace and biomedical engineering. A hierarchical lamellar microstructure exhibited by these composites, with randomly orientated domains in which all ceramic and metallic lamellae are parallel to each other, is the result of the ice crystal formation during freeze-casting or ice templating of preforms from water-ceramic suspensions. In this paper, a single-domain sample of metal/ceramic composite with lamellar microstructure is modelled theoretically using a combination of analytical and computational means. Stress field in the sample containing multiple transverse cracks in the ceramic layer is determined using a modified 2-D shear lag approach and a finite element method. Degradation of stiffness properties of the sample due to multiple transverse cracking is also predicted.

Asphalt pavements in colder climates encounter significantly shortened service lives because of excessive transverse cracking. This paper presents the results for 26 pavement sections in Minnesota that were studied to evaluate the effects of asphalt mix designs on pavement cracking performance. The field performance is presented with various cracking measures and compared with mix design aspects such as amount of asphalt binder, binder grade, and amount of recycling. The disk-shaped compact tension (DCT) fracture energies measured on the field cored samples are also compared with cracking performance. In this study, asphalt pavement sections from several locations were evaluated to encompass various types of asphalt mixtures and asphalt construction types that were commonly used in Minnesota. The amount of transverse cracking for each section was converted into a newly proposed cracking performance measure that accounted for the amount, rate, and timing of cracking. The comparisons between asphalt mixture attributes and cracking performance measures showed that the amounts of total asphalt binder and recycled asphalt binder may not be sufficient. Performance testing, in addition to currently used controls (mix volumetrics and constituent properties), is recommended to ensure good cracking performance. The DCT fracture energy results for companion sections show that mixtures with higher fracture energies exhibit lower amounts of transverse cracking.