Static and Dynamic Behavior of Concrete Lift Joint Interfaces

Abstract

Displacement controlled shear tests on concrete lift joint specimens with different surface preparations are conducted to compare dynamic sliding joint behavior with the static behavior. Experimental results indicate that the coefficient of friction decreases with the increase in normal load, under both static and dynamic shear. The shear strength is dependent on surface preparation. Monolithic specimens and water-blasted joints show higher shear strengths than untreated joints and plane independent joint surfaces. No strength degradation is noticeable under dynamic sliding shear tests since hysteresis loops are very stable. No dependency of shear strength on frequency content of the imposed shear displacements is observed. An empirical lift joint constitutive model is developed as a function of a basic friction coefficient and a roughness friction coefficient that is dependent upon the type of surface preparation. The proposed lift joint constitutive model is used to study the seismic sliding response of a 90-m concrete gravity dam.