Lateral-Torsional Buckling of Structural Concrete Beams: Experimental and Analytical Study: Fid-Bau Portal

Lateral-Torsional Buckling of Structural Concrete Beams: Experimental and Analytical Study

Hurff, Jonathan B. / Kahn, Lawrence F.

Abstract

Precast structural concrete beams have become longer and more slender, increasing the likelihood of a stability failure. Although there are methods to determine the lateral-torsional buckling load for reinforced and prestressed concrete beams, there has been no conformity as to which is the more accurate method, nor do they account for initial imperfections. Six slender, rectangular pretensioned concrete beams were tested and showed that the lateral-torsional stability behavior was similar to that of reinforced concrete beams except for (1) changes in material properties owing to a different stress state and (2) the effects of prestressing on the cracking behavior of the cross section. The stability behavior proved to be sensitive to initial imperfections; therefore, both a geometric nonlinear stability analysis and a simplified equation were developed. The predictive methods were compared with the current and past results, and the analytical methods showed good correlation with all structural concrete experimental results. The results indicate that prestressed concrete beams are susceptible to lateral-torsional buckling and the initial imperfections serve to reduce the buckling load owing to nonlinear geometric behavior and a nonrectangular compression zone.