部分充填式窄幅钢箱-UHPC组合梁抗剪试验研究

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

目的为研究部分充填式窄幅钢箱-UHPC组合梁的抗剪性能,方法对4根倒置组合梁试件通过三点加载方式进行了静载试验,通过研究其负弯矩作用下的破坏形态及变形特征,得到了组合梁的荷载-挠度曲线、应变分布、荷载-滑移曲线、最终破坏形态等。结果试验研究结果表明:UHPC翼板显著提升了组合梁的变形能力和极限承载力;相较于试件SUCB-3(NC翼板),试件SUCB-1(1/2UHPC翼板和SUCB-4(全UHPC翼板))的承载力分别提高了18.2%和27.3%,变形能力则分别增强了38.02%和41.2%;钢纤维的添加能有效地抑制翼板裂缝的开展,钢纤维掺量从0提高到2%,试件的最大裂缝宽度从1.06 mm降低到0.92 mm,变形能力增强了23.61%,承载力则提高了4%。结论提出了考虑钢箱、UHPC翼板和充填混凝土贡献的组合梁抗剪承载力计算公式。

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.