A Model for Shear Strength of FRP Bar Reinforced Concrete Beams without Stirrups

Danying Gao,Changhui Zhang,Hui Yao

doi:10.1155/2020/8881463

Abstract

The shear failure of a reinforced concrete beam generally occurs when the principal tensile stress near the neutral axis is equal to or greater than the tension strength of concrete. In order to set up a model for shear strength for FRP bar reinforced concrete beams without stirrups by the mechanical method, this paper equivalently transformed the FRP bar reinforced concrete rectangular beam with cracks as one composed of ideal elastic material to facilitate the analysis and proposed a new and more reasonable model of shear strength for FRP bar reinforced concrete beams without stirrups. Then, an experimental database including 235 FRP bar reinforced beams without stirrups was compiled to verify the validity of the proposed model. It was found that the values from the proposed model are in better agreement with the experimental results of shear strength of FRP bar reinforced concrete beams without stirrups in comparison with the models in codes.

Highlights

Fiber-reinforced polymer (FRP) bars have been considered as an advantageous alternative to replace steel bars for reinforced concrete structures due to the high-tension strength, durability, and good fatigue properties [1]
Some of the models are expressed as a function of th􏽱e s quare roots of concrete cylinder compression strength [5, 8], whilst the others are functions of the􏽱c u bic roots of concrete cylinder compression strength ( 3 fc′) [6, 7, 9], but none of them is a function of the cubic ro􏽱ot s of the square of concrete cylinder compression strength ( 3 f′c2). e shear strength calculation models provided by ACI 440.1R-15, JSCE-97, GB50608, and BISE-99 were reported to be conservative for the FRP bar reinforced concrete slender beams without stirrups, whilst the CAN/CSA S806-12 model did not well consider the effects of ρf nor Ef [10], and led to excessive
To verify the efficiency that equation (9) captures the effects of the concrete compression strength and the longitudinal FRP bars on shear strength of the FRP bar reinforced concrete beams without stirrups, the values (Vecxp/Vpcred), which are the ratios of the experimental shear strength to prediction values according to the proposed model, and models recommended by ACI440.1R-15, JSCE-97, CAN/ CSA S806-12, GB50608-2010, and BISE-99 are shown in Figures 6 and 7 with fc′ and ρfEf/Ec, respectively

Summary

Introduction

Fiber-reinforced polymer (FRP) bars have been considered as an advantageous alternative to replace steel bars for reinforced concrete structures due to the high-tension strength, durability, and good fatigue properties [1]. E shear strength calculation models provided by ACI 440.1R-15, JSCE-97, GB50608, and BISE-99 were reported to be conservative for the FRP bar reinforced concrete slender beams without stirrups, whilst the CAN/CSA S806-12 model did not well consider the effects of ρf nor Ef [10], and led to excessive. Us, the shear strength Vc of FRP bar reinforced concrete beams is a function of ft.􏽱 e concrete tension strength can be evaluated through the 3 f′c2 in Eurocode􏽱 2 [18]; Vc can be expressed as a function of 3 f′c2 to show the significant effect of fc′ on Vc. In this paper, the primary objective is to propose a new and more ac􏽱c u r ate shear strength model expressed as a function of 3 f′c2 for FRP bar reinforced concrete beams without stirrups by the theoretical method. A database of 235 FRP bar reinforced concrete beams without stirrups was collected to verify the validity of the proposed model. e efficiency of the proposed model and the ACI 440.1R-15, CAN/CSA S806-12, GB50608-2010, JSCE-97, and BISE-99 models were evaluated by comparing the predictions with experimental results in the database

Proposed Model

Experimental Verification and Comparison