A softened membrane model for single-box multi-cell composite box-girders with corrugated steel webs under pure torsion

Abstract

Abstract To analyze the nonlinear torsional behavior of single-box multi-cell prestressed concrete (PC) or reinforced concrete (RC) composite box-girders with corrugated steel webs (BGCSWs), a new theoretical model called unified softened membrane model for torsion (USMMT) is proposed in this study. It is developed from the softened membrane model for torsion which was formerly proposed for the torsional analysis of single-box single-cell PC/RC composite BGCSWs. This proposed model incorporates the different contributions of inner and outer corrugated steel webs (CSWs) in the multi-cell BGCSW to the torsional capacity by introducing a rational relationship of shear strains between inner CSWs and outer CSWs. The satisfactory accuracy of the proposed model is obtained when comparing with the experimental and the finite element analysis results, including the torque-twist curves and the smeared shear strains in concrete slabs and CSWs in the full-range torsional analysis. The comparison indicates that the proposed model is capable of predicting the overall torsional behavior of single-box multi-cell BGCSWs.

Keywords

• Single-box multi-cell box-girders
• Corrugated steel webs
• Softened membrane model
• Nonlinear torsional analysis
• Torque-twist curve
• Shear strain