doi:10.16186/j.cnki.1673-9787.2022090026

Received:2022/09/12

Revised:2022/12/12

Published:2024/01/25

Experimental study on shear strength of partially filled narrow steel box-UHPC composite beam

MO Shixu1,2, XIONG Hao1,2, ZHENG Yan1,2, CHAI Longjie1,2

1.College of Civil Engineering and Architecture，Guilin University of Technology，Guilin  541004，Guangxi，China;2.Guangxi Key Laboratory of New Energy and Building Energy Saving，Guilin  541004，Guangxi，China

Abstract: Objective In order to study the shear performance of partially filled narrow steel box-UHPC composite beams， Methods static load tests were carried out on four inverted composite beam specimens by three-point loading，and the load-deflection curves， strain distributions，load-slip curves， and final damage patterns of the composite beams were obtained by investigating the damage patterns and deformation characteristics under the action of the negative bending moments. Results The results of the experimental study show that：the UHPC wings significantly improved the deformation capacity and ultimate load carrying capacity of the combined beams；compared with specimen SUCB-3 （NC wing），the load carrying capacity of specimens SUCB-1 （1/2 UHPC wing） and SUCB-4 （full UHPC wing） were increased by 18.2% and 27.3%，while the deformation capacity was increased by 38.02% and 41.2%，respectively；the addition of steel fibers can effectively improve the deformation and ultimate capacity of combined beams under negative bending moments.The addition of steel fibers can effectively inhibit the development of cracks in the wing plate，and the maximum crack width of the specimen was reduced from 1.06 mm to 0.92 mm by increasing the dosage of steel fibers from 0 to 2%，and the deformation capacity was enhanced by 23.61%， while the load-bearing capacity was increased by 4%. Conclusion The formula for calculating the shear capacity of the combined beam considering the contribution of steel box，UHPC flange and filled concrete is presented.

Key words:narrow steel box-UHPC composite beam;static load test;shear bearing capacity;steel fiber content