考虑翼缘约束的钢-混组合梁腹板高厚比设计限值研究OA

To study the influence of flange restraint on the web height-to-thickness ratio limit of composite beams,a stiffness ratio coefficient was introduced to quantify the constraining effect on webs from flanges.Based on the relationship between restraint stiffness and web buckling performance,the arctangent function was proposed as a unified formula for calculating both the shear and bending buckling coefficients of the web.Specific coefficients of the formula under negative bending moment were determined using finite element analysis.Using the"yield before buckling"criterion and combining with the buckling equation under com-pound stress,the height-to-thickness ratio limits of the web under pure shear and combined bending-shear were analyzed.Results indicate that,when flange restraint is considered,the height-to-thickness ratio limit for uns-tiffened webs increases by 15%to 28.6%compared with the"standard for design of steel structures",and by 25%to 37.5%compared with the"specification for design of highway steel bridge".Under combined bending-shear stress,the web height-to-thickness ratio limit is affected comprehensively by the shear-compression ratio,stress gradient,and lower flange-web stiffness ratio.Compared with the pure shear condition,when the stress gradient α≥1.75,the negative bending moment relaxes the limit,while when α≤1.25,the limit decreases.The proposed method for calculating the web height-to-thickness ratio limit consid-ers both flange restraint effects and actual stress conditions,demonstrating better economy and accuracy.