Development of Seismic Retrofitting Method and Proposal of Seismic Performance Evaluation Method for Steel Bridge Piers Corrected by Heating

在1995年的阪神-旭日地震中，许多大型钢结构构件遭到破坏。地震发生后，许多杆件的局部屈曲变形通过加热和挤压得到了迅速的纠正。然而，修正像屈曲一样的大变形，构件的极限强度是未知的。因此，有必要对加热纠偏构件的安全性和可靠性进行验证。对原始十字形柱和加热纠偏构件进行了一系列的抗压试验。结果表明，经加热修正的投影板屈曲变形模式随残馀缺陷程度的不同而不同。校正后的投影板的最终变形大于未校正的投影板。然而，加热修正后的投影板的极限强度与原始材料的极限强度几乎相同。为了解释加热修正后的试件压缩性能与…不同的原因对较多的原始试件进行了弹塑性大变形分析。当只考虑残余缺陷时，不能模拟实验现象。这样既考虑了残余缺陷，又考虑了加工硬化引起的屈服应力上升，完全可以模拟实验现象。分析表明，加热修正后的试件屈曲模式发生变化的原因既有残余缺陷，也有加工硬化引起的屈服应力增加。为了验证影响加热修正后的箱形柱受压性能的主要因素，进行了一系列试验，并进行了弹塑性大变形分析。其结果与十字形柱体的趋势一致。阐述了残余缺陷和塑性大变形引起的屈服应力增加两个因素对加热修正后钢构件的压缩性能的影响，并结合十字形柱和箱形柱对桥墩结构模型进行了交变载荷试验。结果表明，如果加热修正时加热温度低于A1相变温度，则在不破坏力学性能的情况下，用水可以很大程度上修正残余缺陷。极限强度是否降低取决于局部挠度的大小，局部挠度仍然没有通过加热完全纠正。因此，虽然恢复到原始状态是希望尽可能地完全恢复到原始状态，但如果完全恢复是困难的，则对反屈曲方向的加热校正应该稍微大一些。较少

In Hanshin-Awaji earthquake (1995), many members of large steel structures were damaged. After the earthquake, the local buckling deformations of many members were rapidly corrected by heating and pressing. However, correcting large deformation like buckling, the ultimate strength of the members is unknown. So it is necessary to confirm safety and reliability of members corrected by heating.A series of compressive tests was carried out for virgin cruciform column and one corrected by heating. According to the results, buckling deformation modes of projection panels corrected by heating were variously changed by the degree of residual imperfection. And deformations up to the ultimate situation of corrected projection panels became larger than those of virgin panels. However, the ultimate strength of projection panels corrected by heating was almost equal to those of virgin materials.To elucidate the reason why the compressive behavior of specimens corrected by heating differs from that … More of virgin specimens, elastic-plastic large deformation analysis was carried out. When considering only residual imperfection, the experimental phenomena could not be simulated. Then considering not only residual imperfection but also the rise of yield stress made by work hardening, the experimental phenomena could be simulated totally. From the analysis, it was elucidated that the reason why the buckling mode of specimens corrected by heating changed was both residual imperfection and the increase of yield stress made by work hardening.In order to verify the major factors affecting compressive behavior of box column corrected by heating, a series of experiment was carried out and it was simulated by elastic-plastic large deformation analysis. The results were same tendency as the case of cruciform column. It was elucidated that two factors as residual imperfection and increase of yield stress involved in large plastic deformation dominated the compressive behavior of the steel members corrected by heating.The alternative load test was carried out for the structural model of a bridge pier with considering the knowledge obtained from cruciform column and box column.According to the results, if heating temperature was made to be under A1 transformation temperature at heating correction, residual imperfection could be largely corrected by using water without spoiling the mechanical properties. Whether the ultimate strength was decreased or not was decided by the magnitude of the local deflection which was remained without completely corrected by heating. Therefore, although the restoration to the original state was desirable to be as complete as possible to the original state, if the complete restoration was difficult, heating correction to the opposite direction of buckling should be performed somewhat larger. Less