Title: Studies on the Seismic Response of Waffle-Flat Plate Buildings
Author(s): M. Rodriguez and R. Meli
Publication: Symposium Paper
Appears on pages(s): 449-464
Keywords: buildings; earthquake-resistant structures; flexural strength; loads (forces); plates (structural members); reinforced concrete; shear strength; stiffness; waffle slabs; Structural Research
Waffle-flat plate buildings are very popular in different countries. Their seismic performance has been very poor. Several research projects on the seismic response of these buildings have been performed at the Instituto de Ingenieria, UNAM; their results and findings are summarized in this paper. First, the main features of the structural system and of its resistance to lateral loads are presented. The most common mechanisms of collapse are described and the observed performance during the 1985 Mexico earthquake is discussed. A case study of building performance during the earthquake is briefly presented. Results of an experimental research on a two-story model of a waffle-slab building are described. The specimen was first tested in a haking table and later subjected to cycles of static lateral loads. The specimen showed a rather poor behavior with very small lateral stiffness and limited energy dissipation capacity. The failure mechanism was mainly governed by the shear and flexural strengths of the columns and by flexural cracking in waffle slabs. Recommendations for the proper use of the system are given, emphasizing the need to combine it with structural walls, bracings, or stiff frames to achieve the necessary lateral stiffness and strength in a building.