Seismic Performance of Joist-Pocket Connections. I: Modeling

By W. Bradford Cross, Assist. Prof., Dept. of Civil Eng., Southern Illinois Univ. at Edwardsville, Edwardsville IL 62026-1800, P.E., A.M. ASCE,

and Nicholas P. Jones, Assoc. Prof., Dept. of Civ. Engrg., The Johns Hopkins Univ., Baltimore, MD 21218-2686, A.M. ASCE.

Abstract:

This paper outlines the development of a technique for the examination of the seismic performance of joist and beam bearing connections in unreinforced masonry structures. An understanding of these "pocket" connections will allow for better estimates of the behavior of brick buildings, and provide a useful tool for the design of seismic retrofit details, particularly in cases when it is imperative to minimize the interventions. A finite element model which accounts for the friction and impact behavior at the diaphragm-to-wall interface is developed. An equivalent coefficient of restitution procedure is described to account for energy loss in collisions between flexible bodies. Several simple but representative examples are presented to illustrate the method and demonstrate its ability to capture the sliding and impact behavior at the connection detail. In the companion paper, an historic brick building that was shaken during the Loma Prieta Earthquake of 1989, is modeled using the approach described herein.