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

在1995年阪神-淡路地震中，许多大型钢结构的构件遭到破坏。地震后，许多构件的局部屈曲变形通过加热和压制得到迅速纠正。然而，校正大变形如屈曲，构件的极限强度是未知的。因此，有必要对加热修正构件的安全性和可靠性进行确认。对原始十字形柱进行了一系列压缩试验，并对其进行了加热修正。结果表明，经加热修正后的投影板屈曲变形模式会随着残余缺陷程度的不同而发生不同程度的变化。修正后的投影板在达到极限状态时的变形比未加工的投影板大。然而，经过加热修正的投影板的最终强度几乎等于原始材料的强度。为了阐明加热后试样的压缩性能与未加热试样不同的原因，进行了弹塑性大变形分析。当只考虑残余缺陷时，实验现象无法模拟。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的上升，可以对实验现象进行全面的模拟。分析表明，热处理后试样屈曲模式发生变化的原因既有残余缺陷的原因，也有加工硬化导致屈服应力增大的原因。为了验证影响加热修正箱形柱抗压性能的主要因素，进行了一系列试验，并采用弹塑性大变形分析进行了模拟。结果与十字形柱的情况相同。结果表明，残余缺陷和大塑性变形时屈服应力的增大是影响加热修正钢构件压缩性能的主要因素。结合十字形柱和箱形柱的知识，对某桥梁桥墩结构模型进行了交替荷载试验。结果表明，在加热校正时，如果将加热温度控制在A1相变温度以下，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，而局部挠度没有经过加热完全修正。因此，虽然希望尽可能完全恢复到原始状态，但如果难以完全恢复，则应对屈曲的相反方向进行较大的加热校正。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