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

(1)由宽厚参数R=0.7的加筋板组成的钢柱混凝土试件的极限强度约为相同截面钢柱试件极限强度的1.2倍，延性约为1.9倍，滞回能约为相应钢柱试件的2.7倍。(2)在反复荷载作用下，桥墩的强度劣化在桥墩构件加筋板屈曲的荷载水平上变得显著，(3)钢管混凝土桥墩的外包混凝土高度应根据外加弯矩和抵抗弯矩的分布来确定。(4)纵向加劲板可以有效地应用于钢管混凝土桥墩，因为外包混凝土可以防止纵向加劲肋的局部屈曲。(5)设置…的钢桥墩更多的R=0.7的加筋板可能会受到像兵库县南部地震这样的强烈内陆地震的严重破坏。(6)在柱高的下部1/4部分填充混凝土的钢柱试件，在单向水平位移较大的情况下，R=0.7的加筋板在钢材部分采用栓钉时发生局部屈曲。(7)桥墩的最大响应加速度约为桥墩底部最大地震加速度的1.3倍。(8)加筋板为R=0.7的钢柱试件，由于横截面拐角处出现纵向裂缝，在几个加载循环次数下，极限强度大幅度下降，而当钢柱试件由R=0.35的加筋板组成时，柱底部焊接处出现横向裂缝。因此，这些部件的焊接设计和制造不仅要考虑强度，还要考虑足够的延性。(9)由R=0.35的加筋板组成的钢桥墩的极限强度和延性不会大幅下降，即使在兵库县曼布地震等强烈地震的作用下也是如此。(10)日本《公路桥梁规范》中的抗震设计方法对内陆型2级和II型地震的抗震设计方法倾向于保守。

(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