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Projects : CUREE-Caltech Woodframe Project

Element 1 - Testing & Analysis
Task - Anchorage Hillside Buildings to Foundation Tests

PI: Yan Xiao (University of Southern California)

Problem Statement

In the 1994 Northridge earthquake more than 300 hillside dwellings suffered structural damage, including destructive collapse of 14 hillside buildings with the loss of five lives. It is estimated that there are approximately 10,000 existing hillside buildings in the City of Los Angeles. A significant portion of them may be hazardous and susceptible to life-threatening collapse or severe structural damage in event of a major earthquake.

The 1994 Northridge earthquake demonstrated that hillside buildings are especially vulnerable to the failure of the diaphragm to foundation connections when subjected to more complicated loading conditions of combined shear and normal forces. This experimental program is proposed to test the diaphragm-to-foundation anchorage connections under simulated seismic loading to verify the efficiency of the hillside connection retrofit.

Main Objectives

The main objectives of the project are to improve the understanding of the behavior of diaphragm-to-foundation connections that are typical in hillside constructions, and to verify the efficiency of retrofit measures as recommended in the Los Angeles City Hillside Woodframe Buildings Retrofit Ordinance and to provide background data to guide the design practice.


The research project involves testing of several large-scale models of hillside building baselevel diaphragm to uphill foundation connections. The testing parameters include the configurations of principal and secondary anchors. An analytical program is devoted to assess the force demand on the anchors due to earthquake loading.

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last updated 03.23.15