不同侧压比荷载下U型约束混凝土拱架全尺寸试验研究

Full scale tests on U-steel confined concrete supporting arches under loads with different lateral pressure coefficients

以直腿半圆形UCC拱架为对象,进行了不同侧压比荷载条件下的全尺寸拱架试验研究,从变形破坏形态、承载力、材料应变等方面进行对比分析,掌握了新型拱架的承载特性和屈服失稳机制。拱架受力初期处于线弹性变形阶段,拱架内力呈显著压弯状态,由于部分截面出现了强度破坏而导致拱架整体屈服,而后随持续加载拱架出现整体结构失稳,进而彻底丧失承载能力。UCC29试验拱架在λ=1.0加载条件下整体屈服承载力为1 230 k N,是相同尺寸U36拱架的1.56倍。拱架屈服承载力随侧压比λ(λ≥0.5)呈指数型降低趋势,且拱架变形形态及危险截面位置也受侧压比影响显著。对于直腿半圆形拱架而言,侧压比在一定范围内越小,拱架内力越接近轴压状态,拱架能够承担的荷载也越高。

Full scale mechanical tests on the new supporting arches with straight-leg and semi-circular shape were performed. The bearing characteristic,bulking and instability mechanism were investigated by comparative analysis on deformation and failure pattern,bearing capacity,steel strain,etc. Tested arches are in the linear elastic deformation stage at the early process of loading,and the inner force of arch is a combination of compressive axial force and bending moment,and the bulking of arch is caused by the strength failure of some sections of its members. Then with the increase of load,the overall structural instability of tested arch occur,subsequently the arches lose the bearing capacity completely. Under the loading condition of lateral pressure coefficient λ = 1. 0,the yielding bearing capacity is 1 230 k N,which is 1. 56 times of the U36 arch with the same size. Along with the increase of λ( λ≥0. 5),the yielding bearing capacity shows an exponentially decreasing trend,and the deformation mode and positions of dangerous sections are changed significantly. The statement of inner force of arch with straight leg and semicircle shape under the lower lateral pressure load comes closer to the axial compression,which make the arch bearing capacity increase.