Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Civil and Environmental Engineering


Maged Youssef


Analysis and design of fire-exposed Reinforced Concrete (RC) frames before and after jacketing with concrete layers are commonly performed using prescriptive methods that rely on the concept of fire rating. These methods were developed based on empirical results on individual RC members subjected to certain fire conditions. In typical fire scenarios, the residual capacity, stiffness and thermal deformations affects not only the local performance of each fire-exposed member, but also the load redistribution and global behavior of the entire frame. In terms of fire safety, the philosophy of the new building codes considers objective-based design as an alternative of the current prescriptive methods. Unfortunately, performing full scale experiments and comprehensive numerical analysis on RC frames are expensive and time consuming. Therefore, this thesis aims at developing a simple yet robust analysis procedure for estimating the post-fire behavior of RC frames before and after repair using concrete jackets.

The study encompasses three main phases. Firstly, the influence of interfacial slip in jacketed RC members on the capacity, stiffness and deformation behavior is assessed. An analytical model is developed to analyze the jacketed sections using the sectional analysis method and considering nonlinear material behavior. The validated model is utilized to conduct a parametric investigation aiming at examining the effect of geometrical and mechanical properties on the performance of the jacketed members and to propose modification factors to account for interfacial slip.

In the next phase, the behavior of individual fire-exposed RC members is investigated. The influence of temperature-load history, support type, initial load conditions, material properties and geometrical characteristics on the complete deformation behavior is examined in view of a proposed comprehensive sectional analysis model. The significance of each parameter is captured by performing detailed statistical analysis on the results to determine the different residual characteristics of each member.

The dissertation is culminated by presenting a case study to illustrate the proposed analysis procedure. The global behavior of an intact, fire-exposed and repaired RC frame is discussed in view of two fire scenarios. The results show the significance of considering the mutual interaction between members to determine load redistribution and residual deformations.