Study on Seismic Characteristics of Partially Concrete-Filled Steel Bridge Piers with Thin-Walled Stiffened Cross Section

(1)宽度-厚度参数R=0.7的加筋板钢柱试件的极限强度约为相同钢截面且未包覆混凝土的相应钢柱试件的1.2倍，延性约为1.9倍，滞回能约为2.7倍。(2)桥梁桥墩在循环荷载作用下的强度劣化在桥墩内构件加筋板屈曲的荷载水平上表现得较为明显，随后在截面角处或柱底处的焊接部位出现裂缝。(3)钢混凝土桥墩内包覆混凝土的高度应根据施加弯矩和阻力弯矩的分布来确定。(4)纵向加筋板可以有效地应用于混凝土填充钢桥墩，因为纵向加筋板的局部屈曲被包裹的混凝土所阻止。(5) R=0.7的加劲板较多的钢桥墩在兵库县南部地震等强烈的内陆型地震中可能受到严重破坏。(6)钢柱试件在柱高下1 / 4处采用螺柱部分填充混凝土，钢柱上部钢筋部分R=0.7的加筋板在一个方向上受到较大水平位移时发生局部屈曲。在钢构件的这种破坏模式下，作为组合柱的效果是不能预期的。(7)所考虑的桥墩最大响应加速度约为桥墩基底最大地震加速度的1.3倍。(8) R=0.7的加筋钢柱试件在少数荷载循环下，由于截面一角出现纵向裂纹，极限强度大幅下降，而R=0.35的加筋钢柱试件在柱底座焊接处出现横向裂纹。因此，这些零件的焊接设计和制造不仅要考虑强度，还要考虑足够的延展性。(9) R=0.35的加劲板组成的钢桥墩的极限强度和延性即使在兵库县曼部地震等强震作用下也没有明显下降。（10）日本《公路桥梁规范》中的抗震设计方法对2级和II级内陆地震倾向于保守设计。少

(1)The concrete-filled steel column specimen consisting of stiffened plates with the width-thickness parameter R=0.7 had about 1.2 times the ultimate strength, 1.9 times the ductility, and 2.7 times the hysteresis energy of the corresponding steel column specimen with the same steel cross section and without encased concrete.(2)The deterioration of the strength of a bridge pier under cyclic loading becomes significant at the loading levels where a component stiffened plate in the pier buckles, and then a crack occurs in welding part at the corners of the cross section or the column base.(3)The height of the encased concrete in the concrete-filled steel bridge piers should be determined according to the distributions of the applied and resistance bending moments.(4)Longitudinally stiffened plates can effectively be used in the concrete filled steel bridge piers, because the local buckling of the longitudinal stiffeners are prevented by the encased concrete.(5)The steel bridge piers with … More stiffened plates of R=0.7 may be seriously damaged by such strong inland type earthquakes such as the Hyogo-Ken Nambu Earthquake.(6)Local buckling occurred in stiffened plate with R=0.7 in the upper steel part of the steel column specimen filled partially with concrete in the lower quarter of the column height by using studs, when it was subjected to large horizontal displacement in one direction. The effect as a composite column can not be expected in the case of this failure mode in the steel part.(7)The maximum response acceleration of the bridge piers under consideration is about 1.3 times the maximum seismic acceleration at their pier bases.(8)The ultimate strength of the steel column specimen with stiffened plates having R=0.7 decreased substantially at a few number of loading cycles because of a longitudinal crack at a corner of the cross section occurred, while a transverse crack occurred at welding part on the column base in the case of the steel column specimen consisting of the stiffened plates of R=0.35. Welding of thess parts should, therefore, be designed and fabricate against not only strength but also adequate ductility.(9)The ultimate strength and ductility of steel bridge piers consisting of the stiffened plates of R=0.35 does not decrease substantially, even after the action of such strong earthquakes such as the Hyogo-Ken Mambu Earthquale.(10)The seismic design method in the Japanese Specification for Highway Bridges is apt to conservative one against the inland type earthquakes of level 2 and type II. Less