Lateral Load Response of Two Identical Bridge Column-Foundation Systems in Warm and Freezing Conditions (05-0431)**
Muhannad T. Suleiman, Lehigh University
Sri Sritharan, Iowa State University
David J. White, Iowa State University

Ambient temperatures in the Midwest and East Coast of the United States typically range from 35oC to -20oC. Cold temperatures below freezing significantly increase the soil shear strength and stiffness. Although the effects are not as significant, the strength of concrete and reinforcing steel are also increased by cold temperatures. Consequently, the lateral load behavior of bridge columns becomes dependent on seasonal weather conditions, which is not addressed in the current design practice. This paper summarizes the results of large-scale cyclic lateral load tests on two identical bridge column–cast-in-drilled-hole shaft systems, installed in glacial till soil, and their predicted behavior. The tests were conducted at 23oC and -10oC. When compared to the warm temperature test, the cold temperature test showed more than twice the elastic stiffness and 39% increase in the lateral strength, while shifting the location of the maximum moment upward by 0.74 m. Using the results from Cone Penetration (CPT) and Pressuremeter (PMT) soil tests, lateral load behavior of the test units were predicted using numerical models that consisted of beam elements representing the column and the shaft and lateral nonlinear springs modeling the soil response. The temperature effects on soil, concrete and steel were accounted for when developing the soil response and moment-curvature behavior of the beam elements. The overall response of the bridge column-foundation systems predicted using the p-y curves developed from CPT matched the measured response more closely than that developed using the PMT since PMT measured the average response of the frozen soil layer.