Recent calibration of ACI 318-08 for concrete structures was focused on the flexural capacity. The objective of this paper is to develop the statistical parameters for shear capacity of reinforced concrete beams. The capacity of shear reinforcement is a function of steel cross section area, yield strength, and spacing of stirrups. In this paper, the capacity of concrete is considered using ACI formulas and other shear capacity models available in literature. The analysis is performed for various reinforcement ratios, longitudinal and transverse, including beams without web reinforcement. The statistical parameters of resistance are determined from the test results. The reliability analysis is performed, and it serves as a basis for the selection of resistance factors. The selection criterion is closeness to the target reliability index. Recommended values of resistance factors are provided for each of the considered shear capacity methods.

Revolutionary developments relating to novel materials of construction and improvements in the behavior of traditional materials have been taking place throughout the 20th century and into the 21st century. These developments have been considerably facilitated by increased knowledge of the atomic and nano structure of materials, studies of long-term failures, development of more powerful instrumentation and monitoring techniques, decrease in cost-effectiveness of traditional materials have necessitated stronger and better performing materials suitable for larger structures, longer spans, more ductility, and extended durability. The last few decades of the 20th century can be described as the decades of concrete admixtures and composite innovation. The 21st century will be the millenium of high-strength, high-performance concrete for the greening of structures. Population growth has magnified the infrastructure demands for new compatible materials and composites for sustainable green structural systems compatible with the needs of the environment. Increased industrialization has resulted in mineral byproduct wastes that are detrimental to the environment. For example, the world’s production of fly ash was over half a trillion tons in 1989. Currently, it exceeds one and a half trillion tons. Some of these environmentally unfriendly by-products, however, can particularly be used in new concrete to the benefit of the environment. The versatility of concrete and its high-performance derivatives will satisfy many future needs and impact on the structural performance of concrete systems in flexure, shear, torsion and their long-term behavior. The present century can become the golden age of environmentally friendly supplementary cementing materials for high-performance concrete. This paper gives a summary of some of the major developments in the art and science of concrete structures and materials technology through the 20th and into the present decade of the 21st century as the greening material for the environmental needs of the infrastructure.

The causes of the nonlinear behavior of concrete until failure are numerous and complex, particularly for nonmonotonic and rapid loadings. A model is presented coupling damage and plasticity including several effects: development and closure of cracks, damping, compaction, and strain rate effects. The idea is to describe, with the same tools, a wide variety of problems, the model is of explicit form, and what makes possible its implementation into explicit numerical scheme well adapted to the treatment of fast dynamic problems. In this context, the finite element "Abaqus explicit" code is used, and the model has been successfully applied during the past few years to model a large range of complex reinforced concrete structures subjected to severe loadings. In this paper, the main model concepts are presented, and some examples of numerical simulations are given and compared with experimental data. The applications proposed are related to quasi-static loading as well as to rapid loading (impact); in particular, one of them is within the framework of an experiment linked to the design of a reinforced concrete rock-shed gallery located in the French Alps. The results show the relevance of the modelling used, which makes some real numerical experiments very useful for complex structures and/or extreme loadings.

The two-dimensional design and behavior of typical reinforced concrete (RC) structures has been extensively studied in the past several decades. Such design requires knowledge of the constitutive behavior of reinforced concrete elements subjected to a biaxial state of stress. These constitutive models were accurately derived from experimental test data on representative reinforced concrete panel elements. The true behavior of many large complex structures, however, requires knowledge of the constitutive laws of RC elements subjected to a triaxial state of stress. The goal of the proposed work is to develop new constitutive relations for RC elements subjected to a triaxial state of stress. To accomplish this task, largescale tests on representative concrete panels need to be conducted. The University of Houston is equipped with a unique universal panel testing machine that was used for this purpose. This universal panel tester is the only one of its kind in the United States, and the only one in the world that allows for both displacement and forcecontrolled load application through its newly upgraded servo-control system. The panel tester enhanced the understanding of the in-plane shear behavior of reinforced concrete elements. Recently, 20 additional hydraulic cylinders were mounted in the out-of-plane direction of the universal panel tester to facilitate testing of concrete elements subjected to tridirectional shear stresses. The addition of these cylinders makes the panel tester the only one of its kind in the world that is capable of applying such combinations of stresses on full-scale reinforced concrete elements. This paper presents the details of the mounting and installation of the additional hydraulic cylinders on the universal panel tester, and preliminary results of large-scale tests of a series of RC panels subjected to three-dimensional shear loads.

Reinforced concrete shear walls are typically modeled with two-dimensional continuum elements. Such models can accurately describe the local behavior of the wall element. Continuum models are computationally very expensive, which limits their applicability to conduct parameter studies. Fiber beam elements, on the other hand, have proven to be able to model the behavior of slender walls rather well, and are computationally very efficient. With the inclusion of shear deformations and concrete constitutive models under a biaxial state of stress, fiber models can also accurately simulate the behavior of walls for which shear plays an important role. This paper presents a model for wall-type reinforced concrete structures based on fiber beam analysis under cyclic loading conditions. The concrete constitutive law is based on the recently developed softened membrane model. The finite element model was validated through a correlation study with two experimentally tested reinforced concrete walls. The model was subsequently used to conduct a series of numerical studies to evaluate the effect of several parameters affecting the nonlinear behavior of the wall. These parameters include the slenderness ratio, the transverse reinforcement ratio, and the axial force. These studies resulted in several conclusions regarding the global and local behavior of the wall system.