考慮鋼材非等向性之多層鋼構架耐震能力之擬彈性分析研究

A Study on Pseudo-Elastic Analysis for Aseismic Capacity of Multiple-Story Steel Frame Considering the Effect of Material Anisotropy

黃聖傑(Seng-Jie Huang)

指導教授 ： 陳清泉

國立臺灣大學/工學院/土木工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02471

摘要

本文主要是探討鋼材非等向性的性質，對於鋼結構架耐震能力的影響研究，由於鋼鈑的非等向性行為，在沿著鋼鈑厚度方向的降伏應力和極限應變，會低於於鋼鈑滾軋方向的降伏應力和極限應變，當應用非等向性鋼構件在鋼構架時，在梁柱構件交接面會產生影響，主要原因是由於梁柱構件交接處，當梁構件受彎矩作用後，會對柱面鋼鈑在厚度方向產生拉力和壓力，因鋼材非等向性行為導致柱面在鋼鈑厚度方向，在受拉後容易產生拉裂破壞，當柱面產生破壞時，無論對於柱構件或者是梁構件，在抗拉強度、抗剪能力、抗彎矩強度甚至是構件韌性上，都有明顯大幅度的下降，甚至導致嚴重破壞的情況。
對於鋼材非等向性的力學行為，本研究主要是透過同時對於鋼柱與鋼樑在降伏應力強度上以不同程度的折減比例，來模擬鋼構件材料非等向性的性質，可能造成構件在各軸向降伏應力強度不同的情況，並以不同程度折減的方式，模擬鋼構件材料非等向性差異程度不同的情況，來評估鋼材非等向性行為對於結構耐震能力的影響程度。本文對於評估耐震能力的所使用的研究方法，是藉由擬彈性分析法以及側推分析法，以求得鋼構架非線性行為，並由結果進行分析與比較。然而，使用的擬彈性分析法是將結構物行為視為彈線性，進行靜力分析或動力分析，求得線性結構物在地震力作用下，結構物內每根構件的受力狀況，依照能量守恆原則關係，並應用擬彈性的原理，將結構物超過彈性範圍的能量，轉換成塑性能量，來推求結構物非線性行為的狀況，以求得結構物基底剪力和頂層側位移的關係，以及結構物的韌性比，作為評估結構物的耐震能力之指標。
由於擬彈性法在評估結構物的耐震能力方面，具有快速和簡便等優點，所以本研究將利用擬彈性分析法以及 ETABS 非線性靜力分析，對多層鋼構架構件在非等向性差異程度不同的情況時，造成鋼構架耐震能力所產生影響程度，進行分析比較與評估，以瞭解鋼材等向性與非等向性差異的程度大小，會對鋼構架耐震能力造成的落差情況。

關鍵字

鋼構架 ； 非等向性 ； 擬彈性分析法 ； 非線性靜力分析 ； 耐震能力評估

並列摘要

This paper is to study the effect of anisotropic property of steel for seismic capacity of steel frame. Due to anisotropic property of steel plate, the yielding stress and ultimate strain is much lower in the through-thickness direction than in rolling direction of steel plate. However, there is an impact on the column faces of beam-column connections for the application of anisotropic steel members in the steel frame. Because beam members of beam-column connection by the effect of moment produce tension and pressure on column faces of beam-column connections, column faces of beam-column connections under tension are prone to a result of lamellar tearing in the through-thickness direction of column with anisotropic property. The tensile strength, shear capacity, moment resisting capacity, and ductility of column members and beam members will significantly go down and even induce serious damage of steel frame if column faces produce lamellar tearing.
The paper is to make use of reducing yielding stress of steel beams and columns for simulating the steel anisotropic mechanical behavior on the effect of stress for assessing seismic capacity of steel frame. Therefore, there are different reduction ratios of yielding stress to simulate differences of anisotropic property of steel member on the effect of seismic capacity of steel moment-resisting frames. Adopting methods of assessing seismic capacity of this research include Pseudo-elastic approach method and pushover analysis to obtain the structure nonlinear behavior as the analysis and comparison of seismic capacity. There is an assumption that structure behavior is linear firmly for the theory of Pseudo-elastic approach method. Firstly, it is essential to carry out members forces of structure under design earthquake by static analysis or dynamic analysis. Then, gradually enlarge the design earthquake, and thus members forces of structure will be amplified by the same scale. The structure behavior will not become inelastic until the first plastic hinge of the structure appears. According to the energy conservation principle, exceeding the elastic strain energy range of the total energy can be converted into the corresponding plastic energy by using Pseudo-elastic approach method with assumption of linear structure to figure out structure nonlinear behavior in the relationship of base shear and roof lateral displacement. Finally, the yielding lateral force, ultimate lateral force, ductility ratio, and collapsed ground acceleration of the structure can be worked out as the seismic capacity assessment index of the structure.
Due to Pseudo-elastic analysis method with the advantages of rapidity, simplicity and convenience on assessing the seismic capacity of structures, this study will make use of the Pseudo-elastic analysis method and pushover analysis of ETABS software to assess the impact of seismic capacity of multi-storey steel moment-resisting frames with differences of anisotropic property of steel member. According to analysis result, do with the comparison and evaluation in order to understand the differences of steel properties between isotropic and anisotropic for impact of seismic capacity of steel frames.

並列關鍵字

Steel Frame ； Anisotropy ； Pseudo-Elastic Analysis method ； Nonlinear static analysis ； Seismic Capacity Assessment

參考文獻

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