INFLUENCE OF DIAPHRAGM FLEXIBILITY ON THE OUT-OF-PLANE RESPONSE OF UNREINFORCED MASONRY WALLS

Can C. Simsir^[1], Mark A. Aschheim^[2], and Daniel P. Abrams ^[3]

1. Research Assistant, Ph.D. Candidate, Mid-America Earthquake Center, University of Illinois, Urbana, IL 61801, simsir@uiuc.edu
2. Assistant Professor of Civil Engineering, University of Illinois, Urbana, IL 61801, aschheim@uiuc.edu
3. Hanson Engineers Professor of Civil Engineering, University of Illinois, Urbana, IL 61801; Center Director, Mid-America Earthquake Center, d-abrams@uiuc.edu

ABSTRACT

The paper concerns the seismic response of masonry buildings—in particular, the effects of diaphragm flexibility on the dynamic response of unreinforced masonry walls responding out of plane. Previous static and dynamic studies of out-of-plane response resulted in midheight or rocking collapse of the walls. These modes of failure were enforced by the test setups. No such failures resulted in the present tests, which were conducted on the earthquake simulator (shake-table) at the University of Illinois. In these tests, inertial loads were applied to the outof-plane walls through the diaphragm element. Different diaphragm stiffnesses and various earthquake ground motions were used. Results from this ongoing experimental study as well as an analytical method to determine the dynamic stability of the out-of-plane walls are reported.

This project is supported by the National Science Foundation through the Mid-America Earthquake Center.

Keywords: Unreinforced masonry, dynamic testing, out-of-plane wall, diaphragm flexibility.

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