Dynamic Characteristics of Post-Tensioned Girders with Web Openings

Abstract

Results of an experimental and theoretical investigation on the dynamic characteristics of post-tensioned concrete girders with web openings subjected to repeated cyclic loading are presented. Rectangular, T and I cross-sectional girders were fabricated and tested. Each cross-sectional group included a girder with none, one, and two openings centered about the midspan for a total of nine test girders. Experimental testing included static, dynamic, fatigue, and ultimate loading of each girder. Fatigue loadings of up to 10,000,000 cycles were applied. The finite element method was used to determine the dynamic characteristics of the tested girders and to conduct an extensive parametric study. It is shown that repeated cyclic loading leads to significant cracking at the openings' corners and a deterioration in the dynamic characteristics of such structural members. In addition, the natural frequencies are significantly influenced by the shape of the prestressing strands and magnitude of the prestress force level.