9416175 Henke The aim of this project is to help advance the Nation's ability to engineer freeway structures to resist earthquakes. The main objective is to provide detailed information on in situ undegraded nonlinear inelastic shear stress vs strain characteristics for the soil deposits at the sites of the three freeway structures that collapsed during the 1994 Northridge earthquake. The information is expected to be of value to analytical investigations aimed at identifying the roles of soil conditions in the collapses. The sites are the I-5/Highway 14 Interchange, Highway 118 close to Woodley, and I-10 at La Cienega. Local soil conditions may have amplified ground motions at these sites. The main feature of the project is that uncertainty caused by test- related disturbances to in situ conditions is expected to be held to a relatively low level. Data is to be measured using a field prototype simplified in situ torsional cylindrical impulse shear testing system currently being constructed for the Federal Highway administration (FHwA). This method provides detailed information on in situ undegraded nonlinear inelastic shear stress vs strain characteristic for soil deposits. The method addresses the well known, but not yet fully-resolved, problem of obtaining detailed information on the soil characteristics of interest without disturbing in situ conditions excessively. This problem can cause considerable uncertainty in the results of earthquake analyses. This project is being co-funded with the FHwA. ***
