Softening models for nonlinear finite element analysis of reinforced concrete panels subjected to pure shear stresses

Dissertant

al-Husayni, Asrar Sumar

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

1999

English Abstract

This research work is devoted to study the softening phenomenon that occurs in (enforced concrete members subjected to shear or torsion loads.

A numerical analysis technique based on a nonlinear finite element method has been used to investigate the effect of the softening on the behavior of reinforced concrete panels subjected to in-plane pure shear stresses for pre and post-cracking levels of stress.

This thesis describes a three-dimensional nonlinear finite element model suitable for the analysis of reinforced concrete members.

Concrete is modeled by using the 20-node brick elements, while the reinforcing bars are modeled as axial members embedded within the concrete brick dement.

Perfect bond was assumed lo occur between the concrete and the reinforcing bars.

The compressive behavior out concrete is simulated by an elasto-plastic work-hardening model followed by a perfectly plastic response.

This is terminated at the onset of crushing.

In tension, a fined smeared crack model has been used with a tension-stiffening model to represent the retained post-cracking tensile stresses and a shear retention model that modifies the shear modulus of rigidity due to cracking.

The nonlinear equations of equilibrium have been solved using the incremental-iterative technique based on the standard and modified Newlon-Raphson methods.

The convergence of the solution was controlled by a load convergence criterion.

The numerical integrations have been carried out using the 27 Gaussian point's integration rule.

An investigation has been carried out using nonlinear finite element analysis to study and verify he validity of the available softening models to be applied for reinforced panels subjected lo pure shear stresses, Also, two softening models were proposed for this purpose, This investigation covered different grades of concrete ranging between 14.5 and 72.2 Mpa.

The results of this investigation revealed that both proposed softening models give results that are better than these predicted by other available models.

Several parametric studies have lien carried out to investigate the effect of some numerical and material parameters on the predicted finite element behavior.

The influence of increasing the grade of concrete on the shear strength of the panels was investigated.

Also, tile effect of transverse longitudinal reinforcement ratios on the post-cracking behavior and shear strength was estimated.

Due to these investigations, four designing charts covering wide range of torcemenl ratios and grades of concrete between 20 and 80 were developed.

Main Subjects

Civil Engineering

Topics

• Concrete
• Reinforced concrete

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-306276