SP-237CD This CD-ROM is a collection of 19 papers presented at a workshop sponsored by Joint ACI-ASCE Committee 447, Finite Element Analysis of Reinforced Concrete Structures, and JCI Committee 016SP, in Maui, Hawaii, USA, in November 2003. A broad range of topics was addressed, including the creation of new experimental data sets for use in developing, calibrating, and validating models; the development and validation of plain, reinforced, and fiber-reinforced concrete constitutive models; new approaches to simulating the response of reinforced concrete continua; new element formations to enable improved simulation of component response; and new computational techniques.

Over the past years techniques for non-linear analysis have been enhanced significantly via improved solution procedures, extended finite element techniques and increased robustness of constitutive models. Nevertheless, problems remain, especially for real world structures of softening materials like concrete. The softening gives negative stiffness and risk of bifurcations due to multiple cracks that compete to survive. Incremental-iterative techniques have difficulties in selecting and handling the local peaks and snap-backs. In this contribution, an alternative method is proposed. The softening diagram of negative slope is replaced by a saw-tooth diagram of positive slopes. The incremental-iterative Newton method is replaced by a series of linear analyses using a special scaling technique with subsequent stiffness/strength reduction per critical element. It is shown that this event-by-event strategy is robust and reliable. First, the example of a large-scale dog-bone specimen in direct tension is analyzed using an isotropic version of the saw-tooth model. The model is capable of automatically providing the snap-back response. Next, the saw-tooth model is extended to include anisotropy for fixed crack directions to accommodate both tensile cracking and compression strut action for reinforced concrete. Three different reinforced concrete structures are analyzed, a tension-pull specimen, a slender beam and a slab. In all cases, the model naturally provides the local peaks and snap-backs associated with the subsequent development of primary cracks starting from the rebar. The secant saw-tooth stiffness is always positive and the analysis always ‘converges’. Bifurcations are prevented due to the scaling technique.

A finite element model is developed for the analysis of fiber reinforced concrete plane stress members failing by mode I fracture. The constitutive law is built on the variable engagement model where the behavior of a fiber composite is obtained by integration of its parts (fibers and concrete matrix) over the cracked surface. In developing the model in this way the formulation is made generally applicable to any type of steel fiber-cement based matrix and to fiber cocktails with any combination of fibers in the mix in any ratios. The model is demonstrated for a reactive powder concrete girder failing in shear using local and non-local modeling. The finite element formulation is shown to be capable of modeling the girder, with good accuracy observed for the global load versus displacement history and is shown to correctly capture the localized shear failure mechanism.

Seismic design provisions for beam-column joints in the AIJ guidelines are based mainly on earlier experimental studies. However, it is necessary to establish a more rational, performance-based design method, especially for joints subjected to two directional seismic forces. This can be accomplished by analytical study of the stress transfer mechanisms in joints. In order to understand the progression of damage in joint concrete, accumulated absorbed strain energy for concrete and reinforcement was calculated from the results of FEM analysis. The stress transfer mechanisms and progression of damage in concrete and reinforcement provide a basis for establishing a more rational, performance-based design method for RC structures.

The purpose of this paper is the development of simplified numerical tools dedicated to seismic analysis of reinforced concrete structures. Beam formulation and constitutive relationships are described to simulate the behavior of shear walls under complex loadings. The attention of this work focuses on the torsion effects and the way to account for cross section wraping for simplified analysis.