Evaluation of seismic performance of existing steel structures considering histories of corrosion and repair

近年来，在日本，由于在所谓的高增长期建造的许多土木工程结构已经达到35-55岁，因此老化结构的数量正在增加。因此，通过适当的维修和改造来确保这些结构的抗震安全性是非常必要的。对于钢结构而言，材料的腐蚀损耗和构件的修复都会引起残余应力的变化，从而引起应力重分布而产生变形。这些缺陷的变化可能对结构的抗震性能有很大的影响。此外，结构中腐蚀和修复的不对称性将导致3D。行为，即使结构在初始阶段具有对称性。考虑到上述事实，本文提出了一种方法来评估腐蚀和修复结构的塑性，韧性断裂和局部屈曲引起的三维极限行为。在该方法中， ...更多信息 精确地考虑了腐蚀和修复造成的材料损失和增加的历史。首先，CFD的适用性进行检查有关腐蚀环境，导致特定的腐蚀模式和幅度。其次，提出了一种新的、精确的腐蚀构件表面粗糙度测量方法。基于锈蚀构件表面粗糙度的详细几何数据，提出了一种基于非线性有限元分析的锈蚀构件延性断裂预测方法。第三，提出了一种基于有限元的三维数值方法来评估腐蚀和修复钢结构的抗震性能，其中腐蚀和修复过程，包括顶升过程中的恒载下可以精确地模拟。最后，将上述数值方法应用于一些实际问题，如材料腐蚀损失引起的焊接残余应力的变化及其对薄壁柱强度的影响，含腐蚀PC钢筋的预应力混凝土梁的残余强度以及腐蚀钢管桩用于高桩墩的抗震性能等。

Recently decrepit structures are increasing in number in Japan, because a lot of civil engineering structures that were constructed during the so-called high growth period have become 35-55 years old. Therefore, it is a strong necessity to ensure the seismic safety of these structures by carrying out proper maintenance and upgrading. So far as steel structures are concerned, the corrosion loss of material and the repair of structural members will cause changes of residual stresses and deformations due to redistribution of stresses. These changes of imperfections may have a large influence on the seismic performance of structures. In addition, asymmetry of corrosion and repair in structures will result in 3D. behavior, even if the structures have symmetry at the initial stage. Taking all the above facts into mind, we herein propose a method to evaluate the 3D ultimate behaviors of corroded and repaired structures caused by plasticity, ductile fracture and local buckling. In this method, … More a history of loss and gain of material by corrosion and repair is precisely considered. First, applicability of CFD is examined concerning corrosion environment that causes specific corrosion pattern and magnitude. Second, a new and accurate method is proposed to measure the detailed surface roughness of corroded members. Based on the detailed geometrical data of surface roughness, a prediction method based on the nonlinear FEM analysis is presented to predict the ductile fracture of corroded members. Third, a FEM-based 3D numerical method is proposed to evaluate the seismic performance of corroded and repaired steel structures, where the corrosion and repair processes including jacking up process under dead load can be precisely simulated. Finally, the aforementioned numerical methods are applied to some practical problems, such as the change of welding residual stresses due to the corrosion loss of material and its effect on the strength of thin-walled columns, residual strength of pre-stressed concrete beam with corroded PC steel bars and seismic.performance of corroded steel pipe piles used for -pile piers Less