A Study on Development of Ultimate Earth quake-Resistance Design and Retrofit Methods for Steel Bridge Piers

本文旨在发展钢桥墩的极限抗震设计和加固方法。为此，本文对钢桥墩的弹塑性性能进行了分析和试验研究。1)强度和延性为了提高钢桥墩的抗震性能(即强度和延性)，考虑了两种方法：(1)对板长细比、柱长细比和加劲肋刚度等结构参数设定一定的限值；(2)在靠近底部的截面中填充混凝土，以防止或延缓板板的屈曲。对于钢管混凝土桥墩，在大量试验和数值分析的基础上，提出了一种极限抗震设计方法。在该方案中，采用Push-over分析来计算荷载-位移关系…更多的是码头。用该方法计算的强度和延性与试验结果进行了比较。此外，还对八角形钢柱的强度和延性进行了类似的分析研究。2)拟动力试验利用1995年1月17日神户地区Hygoken-Nanbu地震时得到的加速度记录，对模拟钢桥墩的钢箱柱试件进行了拟动力试验。结果表明，自振周期和填充混凝土的存在对钢桥墩的地震反应(最大位移反应和残馀位移反应)有显著影响。在试验结果的基础上，提出了最大位移反应与残余位移反应之间的关系，并通过弹塑性地震反应分析进行了验证。另一方面，通过拟动力试验验证了高延性钢桥墩设计方案的有效性。3)弹塑性地震反应分析根据静力和准静力试验结果，建立了钢桥墩的滞回模型。利用拟动力试验结果对所建立的双参数模型进行了验证，并将其应用于研究桥墩在Hyogoken-Nanbu地震作用下的抗震性能。结果表明，对于短墩或低周期桥墩，JMA加速度图是一种非常剧烈的波浪。4)弹塑性循环分析利用ABAQUS程序对箱形或管形截面钢桥墩在循环荷载作用下的弹塑性行为进行了研究，并引入名古屋大学提出的修正的两面模型。分析结果与试验结果的对比表明，修正的双面模型可以较好地预测钢结构的非弹性循环行为。在参数研究的基础上，提出了一些经验公式来预测这种桥墩的强度和延性。较少

The present study is aiming at developing ultimate earthquake-resistance design and retrofit methods for steel bridge piers. For this purpose, elasto-plastic behavior of steel bridge piers is investigated analytically and experimentally. Based on the results obtained from both the analysis and test, the findings can be summarized in the following aspects.1) Strength and ductilityTo improve the seismic performance (i.e., strength and ductility) of steel bridge piers, two ways are considered : (1) to specify certain limits tothe structural parameters such as plate slenderness ratio, column slenderness ratio, and stiffener's rigidity, (2) to fill concrete into the section near the base so as to prevent or delay buckling of plate panels. As for the concrete-filled steel bridge piers, we proposed an ultimate earthquake-resistance design method based on a large numbers of tests and numerical analyzes. In the proposal, a push-over analysis is employed to compute the load-displacement relation … More of the pier. The strength and ductility computed with the proposed method are compared with experimental results. Moreover, a similar analytical investigation on the strength and ductility of steel octagonal section columns is also carried out. Furthermore, the application of the present proposal is extended to generalized commercial software such as MARC and ABAQUS for practical design.2) Pseudo-dynamic TestsSteel box column specimens modeling steel bridge piers are tested pseudo-dynamically using the accelerograms obtained during the Hygoken-nanbu earthquake that struck Kobe area on Jan.17,1995. The results indicate that the natural period and presence of the filled-in concrete have a significant effect on the seismic response (maximum displacement response and residual displacement response) of steel piers. A relation between the maximum displacement response and residual displacement response is proposed on the basis of the test results, and verified by an extensive elasto-plastic seismic response analysis. On the other hand, the validity of the proposal for designing high ductility steel bridge piers is verified by the pseudo-dynamic test.3) Elasto-plastic Seismic Response AnalysisFrom the results of static and quasi-static tests, a hysteresis model of the steel bridge pier is constructed. The developed model named 2-Parameter Model is verified using the pseudo-dynamic test results, and applied to clarify the seismic behavior of steel bridge piers under the Hyogoken-nanbu carthquake. The results show that the JMA accelerogram is a tremendously severe wave for short piers or those with low natural periods. Also, a hysteresis model is constructed for the concrete-filled steel bridge piers.4) Elasto-plastic Cyclic AnalysisElasto-plastic Behavior of steel bridge piers with box or pipe sections under cyclic loading is studied using the ABAQUS program with the inclusion of the modified two-surface model developed at Nagoya University. Comparison between the analytical and experimental results indicates that the modified two-surface model can be used to predict the inelastic cyclic behavior of steel structures with good accuracy. From the parametric study some empirical formulas are proposed to predict the strength and ductility of such piers. Less