体外预应力钢-混凝土组合连续梁的试验研究及有限元分析

与承受正弯矩的简支梁不同,连续梁中支座部分承受负弯矩,组成组合梁的钢板件受压力作用,其力学性能受稳定控制,不考虑稳定影响的规范简化塑性算法会带来不安全的结果.以Ⅱ类、Ⅲ类组合梁和是否配置预应力筋为参数,进行了两组共四根连续组合梁的单调加载对比试验.试验结果表明:无论预应力连续组合梁或是普通连续组合梁,最终破坏特征均为负弯矩区混凝土开裂,钢腹板局部屈曲,整个截面畸变失稳,正弯矩区混凝土板压碎；正弯矩区的承载能力可由简化塑性计算方法计算,而负弯矩区的受力性能由稳定控制,影响其承载能力的主要因素为板件的宽厚比所表征的截面种类,考虑屈曲的承载力计算方法与试验结果吻合.对各组合梁进行了有限元数值分析,分析考虑界面滑移、预应力、稳定等影响,结果和试验吻合较好.

Experimental Study and FEM Analysis of Externally Prestressed Steel-Concrete Composite Continuous Beams

Unlike simply supported beams under positive moment,the ultimate load carrying capacity of continuous steel-concrete composite beams is usually limited by either the local buckling failure of steel section or the distortional lateral buckling near interior supports,which is because the steel plate under the negative moment near interior is subjected to compression and inclined to instability.However,the simplified plastic theory taking no account of the instability of the beam will lead to a unconservative result.Four full-scale continuous composite beams were tested,among which two were two-span beams with class 2 cross-section and two were three-span beams with class 3 cross-section.One of the two-span beams was a conventional non-prestressed composite beam,and the other was a composite beam prestressed with external tendons in both the positive and negative moment regions.One of the three-span composite beams was non-prestressed,and the other was prestressed only in the negative moment regions with external high-strength tendons.The experimental results indicates that all beams collapsed with the characteristic of concrete crushing in sagging moment,and the web local buckling and distortional buckling of the steel beam.The capacity of beams in positive moment can be calculated by simplified plastic theory,while the capacity of beams in negative moment is affected by section classification divided by width to thickness ratio of the plate,the simplified calculation method based on the web buckling is agreed well with the experimental results.A numerical analysis was conducted for all the beams considering interface slipping,prestressing force,and so on,which agrees well with the experimental results.