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Much of the post-war reinforced and prestressed concrete infrastructure in North America and Europe is reaching its design life and engineers are in need of tools that can be used to assess the shear behavior of these structures. The Compression Field Theory (Collins, 1978) and the Modified Compression Field Theory (Vecchio and Collins, 1986) form the basis of a suite of design procedures and software that engineers can use to assess concrete structures subjected to shear. The complexity of these tools varies from simple hand calculations, such as the sectional design procedures or strut-and-tie procedures in CSA A23.3-14 and AASHTO-LRFD, to sectional software tools, such as Response-2000, and full finite element programs such as VecTor2. This paper describes how such tools can be used to evaluate shear-critical structures in the context of assessing inventories of bridge structures. A preliminary crack assessment procedure, capable of providing estimates of the residual capacity of bridge girders based on crack slips and crack widths, is also presented. This procedure is based on the Pure Mechanics Crack Model and builds on existing compression field approaches. The tool is envisioned as a means of moving from traditional bridge inspection procedures to more complex methods, based on the theoretical advancements that have been made over recent decades.

The vertical shortening of tall buildings is not negligible, and it is important to account for these deformations to minimize differential movement and ensure that the finished building is level. Compensation via superelevation is common in reinforced concrete construction, but traditional methods of calculating these corrections require stepwise analysis accounting for construction sequence nonlinearity. In this paper, the shortening subsequent to storey construction is derived based upon the elastic displacement profile of the full structure. It is shown that the shortening prior to storey construction may be approximated as a parabola. Long-term volumetric effects may also be included using a strain multiplier approach. The simplified formulation is validated by comparison with detailed construction sequence finite element analyses for a sample column and a case-study wall, showing excellent agreement at a fraction of the computational cost. The proposed method therefore gives practicing engineers a conceptually simple but theoretically sound way to account for vertical shortening in tall reinforced concrete buildings.

A series of three shear panels with transverse reinforcing ratios ranging from 0.23 to 0.68% were tested to failure under reversed cyclic loading. All of the tests showed a reduction in strength of at least 20% with respect to predictions from reliable monotonic analyses. Extensive experimental results including strain distributions and cracking patterns were analyzed to explain this discrepancy, and it was determined that shear behavior under reversed cyclic conditions is not well captured by a single rotating crack model; rather, explicit consideration of both diagonal crack systems is required. This analysis has shown that the behavior can be rationally explained by considering the evolution of crack slip and crack closing hysteresis.

As the desire for high performance buildings increases, a number of solutions to enhance the dynamic response of structures have been explored and implemented. In recent years, base isolation has become a practical and effective strategy for earthquake resistant design. To this end, a number of isolation solutions are currently available. Among these, laminated lead rubber bearings and friction pendulum devices have been most widely used in the last 25 years. Recent studies have explored the possibility of employing flat or curved sliding-surface base isolators with variable friction coefficients. These new types of devices have been shown to be capable of performing theoretically better than traditional sliding isolators in light of their higher energy-absorption capacity. This paper provides insight into the mechanics of variable friction sliding isolators, exploring viable ways of dealing with these types of elements from a numerical point of view. A number of 2D non-linear time history analyses, in which the new elements are treated as non-linear translational spring elements, are conducted and the results are discussed in detail.

The goal of the presented research is to experimentally investigate the influence of reversed-cyclic pure shear loading on the behaviour of reinforced-concrete elements, and to formulate simple analytical models which capture the defining features of non-monotonic shear behaviour. This paper details the reversed-cyclic pure shear testing of three specimens containing varying amounts of transverse reinforcement. The results demonstrate that using monotonic predictions for reversed-cyclic shear strength can be significantly unconservative, with strengths as much as 25% lower than monotonic predictions. A fixed-crack model which accounts for crack-closing behaviour is introduced in order to model the load path-dependent behaviour of these experiments.

In order to meet desired seismic performances, it is increasingly evident that engineers require reliable methods for the estimation of seismic demands on both structural and non-structural elements. To this end, current design codes incorporate simplified methods for the prediction of acceleration demands on secondary structural and non-structural elements for buildings with fixed bases. However, no guidance is currently provided as to how to estimate the seismic demand on nonstructural elements in base isolated structures. In such structures, large floor accelerations may still be recorded, particularly in the case of higher mode interactions or horizontal-vertical coupling effects. In all cases, determining the seismic demand on non-structural elements is necessary in order to be able to perform a rational design of those elements, and to be able to effectively control their seismic response. In order to take a step towards the formation of accurate yet simplified methods of predicting peak floor accelerations and floor spectra in base isolated structures, this analytical work examines the response of a number of base isolated case study structures subjected to a series of ground motions of varying intensity. The results of the non-linear time history analyses are used to identify the factors that appear to affect the shape and intensity of acceleration demands on secondary structural and non-structural elements.