[CCoE Notice] Ph.D. Defense Announcement

[Khator, Suresh]

Dear Cullen College Faculty,

Please encourage your students if they are interested in this area.

Suresh Khator
_______________________________________________________
Suresh K. Khator, Ph.D., P.E.                         Phone: 713-743-4205
Associate Dean, College of Engineering    Fax: 713-743-4214
University of Houston                                     Email: skhator at uh.edu
E421 Engineering Bldg 2                                www.egr.uh.edu/ie
Houston, TX 77204-4008

Behavior of Reinforced Concrete Elements Subjected to a Tri-Directional Shear Load Using a State-of-the-Art Panel Tester

Ph.D. Dissertation Defense
By Moheb Labib
March 2nd, 2011, 10:00 am at CEE Conference Room

Committee Chair:               Dr. Ashraf ayoub

Committee Members: Dr. Thomas T. Hsu, Dr. Abdeldjelil Belarbi, Dr. Y. L. Mo, Dr. Gangbing Song , Dr. Farouk Attia

Abstract

The two-dimensional design and behavior of typical reinforced concrete (RC) structures has been extensively studied in the past several decades by investigating the constitutive behavior of reinforced concrete elements subjected to a bi-axial state of stress. The true behavior of many large complex structures, however, requires knowledge of the constitutive laws of RC elements subjected to a tri-axial state of stress. The goal of this investigation is to develop new constitutive relationships for RC elements subjected to a tri-directional state of stresses. Recently, the panel tester at University of Houston was upgraded to facilitate testing of concrete elements subjected to tri-directional shear stresses. The addition of these jacks makes the panel tester the only one of its kind in the US that is capable of applying such combinations of stresses on full-scale reinforced concrete elements. This dissertation presents the details of the mounting and installation of the additional hydraulic jacks on the universal panel tester. The investigation involved conducting an experimental program to test several reinforced concrete elements subjected to different combinations of in-plane and out-of-plane shear stresses. Increasing the applied out-of-plane shear stresses reduced the membrane shear strength of the elements. The effect of applying out-of-plane shear stresses on the in-plane shear strength for the elements was represented by modifying the softening coefficient for the compression strut of the membrane element to account for out-of-plane shear stresses. The modified model was able to capture the ultimate capacity and in-plane shear stress-strain curve of the tested elements up to the peak point. The effect of the in-plane shear reinforcement ratio on the interaction between in-plane and out-of-plane shear stresses was evaluated. The model also was implemented in the Finite Element package FEAP and was used to predict the ultimate capacity of many structures subjected to combination of in-plane and out-of-plane shear stresses. The results of the analytical model were used to develop simplified design equations for members subjected to bi-directional shear loads. The applied out-of-plane shear load was resolved in two equal out-of-plane shear components to construct tri-directional shear interaction diagrams.

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