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Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. The significance of an integral bridge design is that it avoids durability and recurring maintenance issues with bridge joints, and maybe bearings, which are prevalent in traditional bridges. Integral bridges are less costly to construct. They require less maintenance and therefore cause less traffic disruptions that incur socio-economic costs. As a consequence, integral bridges are becoming the first choice of bridge design for short-to-medium length bridges in many countries, including the UK, USA, Europe, Australia, New Zealand and many other Asian countries. However, integral bridge designs are not without challenges: issues that concern concrete creep, shrinkage, temperature effects, bridge skew, structural constraints, as well as soil–structure interactions are amplified in integral bridges. The increased cyclic soil–structure interactions between the bridge structure and soil will lead to adverse soil ratcheting and settlement bump at the bridge approach. If movements from bridge superstructures were also transferred to pile-supported substructures, there is a risk that the pile–soil interactions may lead to pile fatigue failure. These issues complicate the geotechnical aspects of integral bridges. The aim of this paper is to present a comprehensive review of current geotechnical design practices and the amelioration of soil–structure interactions of integral bridges.

The nonproportional multiaxial ratchetting of cast AZ91 magnesium (Mg) alloy was examined by performing a sequence of axial–torsional cyclic tests controlled by stress with various loading paths at room temperature (RT). The evolutionary characteristics and path dependence of multiaxial ratchetting were discussed. Results illustrate that the cast AZ91 Mg alloy exhibits considerable nonproportional additional softening during cyclic loading with multiple nonproportional multiaxial loading paths; multiaxial ratchetting presents strong path dependence, and axial ratchetting strains are larger under nonproportional loading paths than under uniaxial and proportional 45° linear loading paths; multiaxial ratchetting becomes increasingly pronounced as the applied stress amplitude and axial mean stress increase. Moreover, stress–strain curves show a convex and symmetrical shape in axial/torsional directions. Multiaxial ratchetting exhibits quasi-shakedown after certain loading cycles. The abundant experimental data obtained in this work can be used to develop a cyclic plasticity model of cast Mg alloys.

The cyclic deformation of VHB 4910 dielectric elastomer is experimentally investigated by performing a series of strain-controlled and stress-controlled pure-shear-like cyclic tests at room temperature. In the strain-controlled cyclic tests, obvious Mullins effect is observed in the first cycle, and continuous stress softening is characterized in the subsequent cycles; the Mullins effect and continuous stress softening are intensified by prescribing larger peak strains and higher strain rates. In the stress-controlled cyclic tests, remarkable ratchetting takes place, and its evolution becomes more significant if higher stress levels, lower stress rates and longer hold time at peak stress are prescribed. Moreover, a partial recovery of residual strain indicates that, besides obvious hyper-elasticity, the VHB 4910 dielectric elastomer also exhibits both recoverable viscoelasticity and measurable irrecoverable visco-plasticity during the cyclic tests.

At room temperature, the cyclic softening/hardening characteristics and ratchetting behaviors of axle steel EA4T were experimentally observed by considering uniaxial and non-proportional multiaxial cyclic loading paths. The effects of loading conditions and loading paths on low-cycle fatigue behaviors were discussed. The experimental results are obtained as follows: Firstly, under strain controlled monotonic tension, the yield strength of axle steel EA4T depends on the loading strain rate (rate-dependent). Secondly, under symmetrical strain controlled cyclic load, axle steel EA4T shows cyclic softening characteristics, and the cyclic softening characteristics depend on strain amplitude, strain rate and non-proportional multiaxial cyclic strain loading paths. Finally, under asymmetric stress controlled cyclic load, the ratchetting behaviors of axle steel EA4T is greatly dependent on the stress level, stress rate and multiaxial stress loading paths.

This paper presents the results of experimental studies and numerical simulations of the ratcheting for the PA6 aluminum. In the initial determination of the material hardening parameters, the samples were subjected to the symmetrical strain-controlled cyclic tension-compression test. The experimental stress-strain curve was compared with the numerical one obtained for non-linear Frederick-Armstrong and Voce models. For better fitting of both curves, the optimization procedure based on the least-square method and the fuzzy logic was applied. After establishing the hardening parameters, numerical simulations of the ratcheting were made. The boundary value problem was solved by means of discrete analysis. The data (force and displacement) obtained in numerical computations were used to control the ratchetting experiment. The results of experiments and numerical calculations were compared. Good convergence proves the reliability of the determination of material hardening data.

The cyclic deformation and corresponding internal heat production of ultra-high molecular weight polyethylene (UHMWPE) polymer were investigated under the uniaxial strain-controlled and stress-controlled cyclic loading conditions. It is seen that the UHMWPE behaves basically a cyclic stabilizing feature since the responding stress amplitude does not remarkably change during the cyclic loading, except for that at high strain rate (where an obvious cyclic softening is caused partially by the thermal softening); an apparent mean stress relaxation occurs in the asymmetrical strain-controlled cyclic tests, and the degree of mean stress relaxation increases with the increasing mean strain; an obvious ratchetting takes place in the asymmetrical stress-controlled cyclic tests, and the ratchetting strain depends greatly upon the applied mean stress and stress amplitude, as well as the prescribed stress rate. Moreover, it is found that the temperature on the surface of specimen increases apparently in the uniaxial strain-controlled cyclic tests and the temperature variation becomes more remarkable when the prescribed strain rate is higher. However, the temperature variation is not so apparent in the uniaxial stress-controlled cyclic tests due to much smaller responding strain amplitude.

In this paper, a phenomenological constitutive model is constructed to describe the uniaxial ratchetting (i.e., the cyclic accumulation of inelastic deformation) of soft biological tissues in the framework of finite viscoelastic-plasticity. The model is derived from a polyconvex elastic free energy function and addresses the anisotropy of cyclic deformation of the tissues by means of structural tensors. Ratchetting is considered by the evolution of internal variables, and its time-dependence is described by introducing a pseudo-potential function. Accordingly, all the evolution equations are formulated from the dissipation inequality. In numerical examples, the uniaxial monotonic stress–strain responses and ratchetting of some soft biological tissues, such as porcine skin, coronary artery layers and human knee ligaments and tendons, are predicted by the proposed model in the range of finite deformation. It is seen that the predicted monotonic stress–strain responses and uniaxial ratchetting obtained at various loading rates and in various loading directions are in good agreement with the corresponding experimental results.

A moving train subjects a rail cross section to many wheel passes and heat generation at the interface from bulk friction and microslip. Frictional heating at the interface causes the temperature of the contacting rail surface and wheel surface to rise. After the train has passed, the rail temperature drops to ambient till the next train arrives. Wheels, on the other hand, pick up the frictional heat input continuously and hence their steady state temperature could be much higher than that of the rail. A hot wheel provides an additional temperature rise at the rail surface. The accompanying thermal stresses and thermal softening may enhance the rail wear rate. This has been investigated in the present study. A ratchetting failure-based computer simulation has been employed to assess the wear rate of a pearlitic rail steel. It is found that the thermal stress effect on wear rate is only the modest, but thermal softening can enhance the wear rate by up to an order of magnitude for the conditions considered.

The stress-strain behaviors were investigated by monotonic and cyclic stressing tests for high density aluminum foam at room temperature. The cyclic accumulations of deformation for the material were measured in varied loading levels. The effects of mean stress and stress ratio on the ratcheting strain were discussed. The experimental results show that tension response is different from the compressive response. There is obvious cyclic accumulations of deformation (i.e., ratcheting effect) under compression-compression cyclic loading even if the holistic stress-strain response is linear. And the ratcheting of aluminum foam greatly depends on mean stress and stress ratio in asymmetric stress cycling. The experimental rules and data are significant for constitutive description and numerical simulation of aluminum foam.

A previously published model for plasticity assessment in rolling contact, based on a simplification of the non- linear kinematic and isotropic hardening model of Chaboche and Lemaitre, is discussed, and an update is introduced in order to improve its accuracy in the plastic strain prediction within the region just underneath the contact surface. The update is based on a correction of the yield limit and of the strain rate as a function of the load ratio of the tensile stress in the direction parallel to the contact surface. The effectiveness and the accuracy of the updated model in not too severe conditions are demonstrated through comparisons with results obtained by finite element model (FEM) analyses. An application of the model to some experimental results obtained on rail and railway wheel steels is also carried out, and quite good agreement is found in plastic strain prediction, although some discrepancies are found. The method appears to be a valid tool for practical application, especially for its ability of combining the effects of different phenomena and of simulating a number of cycles of the order of millions in a reasonable time.