STRUT-AND-TIE MODELLING OF DEEP BEAMS -AN APPRAISAL

Abstract

The effect of the amount of transverse reinforcement on the efficiency factors of steeply inclined bottle-shaped struts made of normal-strength and high-strength concrete have been experimentally investigated. The amount of transverse reinforcement provided in the form of horizontally oriented rebars was taken as zero, 0.0031, 0.0046 and 0.0069 when expressed in terms of reinforcement ratio. The results show that efficiency factor was influenced by transverse reinforcement content and the steepest increase of 25% and 30% for the normal-strength and high-strength concrete bottle-shaped struts respectively was observed when the transverse steel was increased from zero to 0.003 1. The increase in strut efficiency factor for transverse reinforcement contents beyond 0.0031 was relatively small. Service load crack widths in all the bottle-shaped struts across all the transverse reinforcement contents under investigation were less than 0.3 mm. An optimum 0.003 transverse reinforcement ratio was confirmed for both normal-strength and high-strength bottle-shaped struts.