多钢种混用钢梁静力承载性能试验研究与分析

Experimental Study and Analysis of Static Load-Bearing Performance of Hybrid Steel Girders

为探究不同腹板高厚比和钢种组合对钢梁静力承载性能的影响,分别设计制作了1个同钢种钢梁和3个多钢种混用钢梁,并对试件进行四点弯曲试验,得到各试件的破坏形态、荷载-位移曲线、荷载-应变曲线、腹板和翼缘屈服荷载以及极限荷载等,并且将理论计算值与试验值进行对比分析;然后利用有限元ABAQUS进行非线性屈曲分析,将计算结果同试验结果进行对比,验证有限元模型的合理性,基于此进行参数分析,进一步探究腹板高厚比和钢种组合对钢梁静力承载力的影响,同时结合用钢量变化分析改变腹板高度、腹板厚度和腹板强度的经济性;最后将参数分析所得翼缘屈服弯矩、塑性极限弯矩、弯扭屈曲临界弯矩与相应理论公式计算结果相对比,为多钢种混用钢梁的设计提供参考。结果表明:1)试件M-1翼缘屈服荷载比试件S-1翼缘屈服荷载大8.7%,说明在两个试件设计高厚比与采用GB 50017—2017《钢结构设计标准》计算所得相应高厚比限值的比值相同时,多钢种混用钢梁设计承载能力略优于同钢种钢梁。因此实际结构中,当腹板高厚比较大时,翼缘可采用更高强度等级钢材,同时腹板可采用较低强度钢材,形成多钢种混用钢梁以代替同钢种钢梁,可适当提高钢梁静力承载能力,同时节省钢材用量;2)当截面高度增大,试件腹板屈服荷载有所提高,试件M-3腹板屈服荷载比M-1高12.7%,初始缺陷对钢梁承载能力的影响主要体现在加载后期,因腹板高厚比增大,其初始缺陷程度会增大,同时承载力会提升,故与试件M-1相比,试件M-2和M-3翼缘屈服对应荷载相差不大,破坏荷载分别降低了4.7%和9.4%;3)通过增大腹板强度等级,用钢量提高7%时翼缘屈服弯矩的提升仅7%,效果不佳;增大腹板高度时翼缘屈服弯矩的提升效率可达到增大腹板厚度对应提升效率的8倍;4)多钢种混用钢梁翼缘屈服弯矩、塑性极限弯矩和弯扭临界弯矩均可参考相关文献中理论计算公式进行确定。

In order to investigate the effect of different height to thickness ratio of web and steel grade combinations on the static load carrying performance of steel beams,one same-grade steel beam and three Hybrid steel girders were designed and fabricated respectively,and four-point bending tests were conducted on the specimens to obtain the damage pattern,load-displacement curve,load-strain curve,corresponding load of web and flange yielding and ultimate load of each specimen,and the theoretical calculated values were compared with the experimental values.Buckling analysis was then performed by ABAQUS,and the calculated results were compared with the experimental results to verify the reasonableness of the finite element model.After that,parametric analysis was carried out to further investigate the effect of height to thickness ratio of web and steel grade combinations on the static load carrying performance of steel beams,and to analyze the economics of changing web height,web thickness and web strength with the variation of steel consumption.Finally,the flange yielding moment,plastic limit bending moment and critical moment of bending and torsional buckling obtained from the parametric analysis are compared with the results of the corresponding theoretical equations to provide some suggestions for the design of hybrid steel girders.The results show:1)The yield load of specimen M-1 flange is 8.7%larger than that of specimen S-1 flange,which indicates that the design capacity of Hybrid steel girders is slightly better than that of the same steel girders under the condition that the ratio of height to thickness ratio of web is the same as that of calculated value of the specification GB 50017—2017 Steel Structure Design Standard.Therefore,in the actual structure,when the web height to thickness ratio of web is large,the flange can use higher strength grade steel,while the web can use lower strength steel,forming Hybrid steel girders instead of the same steel girders,which can appropriately improve the static bearing capacity of steel girders and save the amount of steel at the same time;2)When the height of the cross-section is increased,the yielding load of web of specimen is improved,and the yielding load of web of specimen M-3 is 12.7%higher than that of M-1,the effect of initial defects on the load carrying capacity of steel beams is mainly reflected in the late loading stage,because the web height to thickness ratio of web increases,the degree of its initial defects will increase,and at the same time,the load carrying capacity will be improved.Therefore,compared with specimen M-1,specimens M-2 and M-3 flank yielding corresponding to the load is not a big difference,and the destructive loads are reduced by 4.7%and 9.4%,respectively;3)By increasing the strength grade of the web,the steel consumption is increased by 7%,and the improvement of flange yielding moment is only 7%,which is ineffective;the improvement efficiency of flange yielding moment can reach 8 times of the improvement efficiency corresponding to the increase of the web thickness when increasing the height of the web;4)The flange yielding moment,plastic limit moment and torsion critical moment can be determined by referring to the corresponding theoretical calculation formula.