Structural behavior of full-scale precast posttensioned girder with substandard transverse reinforcement–experimental and analytical study

Abstract

Rapid expansion of developed cities create problems mainly attributed to traffic congestions. Recently, Bangkok has faced rapid growth and the expanded neighborhoods require convenient public transport to be linked with central Bangkok and other parts of Thailand. Monorails can be an exceptional alternative to conventional skylines and subways thankfully to their excellent climbing abilities, lower noise, shorter constructions periods, and their capabilities to be adapted within limited spaces. Recently, Mass Rapid Transit Authority adopted monorail system to facilitate public in Bangkok's expanding neighborhoods. A four-span continuous posttensioned girder system has been proposed for the straddle monorail system. Current study focuses on the structural response of full-scale precast posttensioned (FPP) end girders in the proposed monorail system. Results suggested that the girder remained undamaged under service load while exhibiting a linear load versus vertical deflection response. Failure under ultimate load was accompanied by crushing of concrete, buckling of compression longitudinal bars and posttension tendons at the midspan. Further, experimental rosette strains suggested that concrete strains remained well below the ultimate of strains in the vicinity of high shear zones of the girder. Therefore, these results augment that the proposed design practice is safe against shear and the proposed girder can safely be used as the end girder in four-span straddle monorail system. Nonlinear analysis of the girder was performed using advanced tool for engineering nonlinear analysis by adopting its built-in constitutive laws for concrete and steel reinforcement. Predicted analytical response of FPP was in good agreement with experimental results in terms of load-deflection curves, crack patterns, and failure mode. © 2022 International Federation for Structural Concrete.