兩層樓子構架高強度箱型鋼柱耐震試驗與模擬分析

Seismic Tests and Analyses of Two-Story Subassemblages With a High-Strength Steel Box Column

熊厚淳(Hou-Chun Xiong)

指導教授 ： 周中哲

國立臺灣大學/工學院/土木工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202002644

摘要

本文延續陳冠維 (2019)的研究，將其研究中寬厚比b/t不同的兩組空心箱型鋼柱(HBC)試體縮尺50%後放入兩層樓子構架中於固定軸力下進行反覆側向載重，觀察整體構架與各桿件的行為，並將構架中一樓柱的行為與兩端都完全束制其旋轉自由度(Fixed-Fixed)的單柱實驗結果比較，探討箱型鋼柱於不同邊界條件下差異。實驗結果顯示當抗彎構架進入非線性後，其彎矩重新分布的趨勢會造成規範對於結構低樓層中強柱弱梁的保護機制失效，使結構發生不理想的破壞機制。此外也發現鋼柱於構架中的最大彎矩會略大於雙曲率單柱實驗的結果，而最大強度前塑性轉角雖然因為實驗條件略有差異(載重歷時不同)需要進一步實驗驗證，但鋼柱的最大強度前塑性轉角於構架中並不會比雙曲率單柱實驗的結果差，顯示目前使用雙曲率單柱實驗的結果來進行結構設計是安全，甚至可能較為保守的。
本研究也比較國內外規範與研究在預測箱型鋼柱背骨曲線上的差異，並與實驗結果比較，結果顯示ASCE-41與NIST對箱型鋼柱在大軸力下其最大彎矩的預測都非常保守，而Chou and Chen (2020)提出的預測公式則能反映箱型鋼柱在大軸力下最大彎矩遠大於降伏彎矩的現象。
同時研究中也使用非線性結構分析軟體(PISA3D)建立實驗子構架試體的結構分析模型並將預測之背骨曲線放入桿件內，比較模擬與實驗結果的差異，模擬結果顯示使用PISA3D中的Fracture Material搭配Chou and Chen (2020)提出的背骨曲線預測公式可有效模擬箱型鋼柱子構架整體的行為。

關鍵字

空心箱型鋼柱 ； 梁柱抗彎構架 ； 耐震行為 ； 背骨曲線 ； 非線性分析

並列摘要

This study continued Chou and Chen's work in 2019. Two of their steel hollow box column (HBC) specimens, with different width-to thickness (b/t) ratio, were 50% scaled down and placed into a two-story subassemblage of moment frame respectively. The subassemblages were tested under 40% axial load and displacement-control cyclic loading. The behaviors of overall subassemblage and their members were examined, and were compared with those in Chou and Chen's research to show the effect of different boundary conditions on steel columns.
Experimental results showed that after the subassemblages went in to nonlinear phase, the moment redistribution tended to increase the moment in column bottom of lower floors, while the moment in column top would keep constant or even decrease despite the column top were not yet yielding. This phenomenon might result in column bottom in lower floors of moment frames which were designed complying the strong column-weak beam rules given by AISC yielding, causing undesirable mechanisms.
Experimental results also indicated that the ultimate moment strength of steel box columns in moment frames is slightly higher than that in common-seen isolated column tests. And the pre-peak plastic rotation of steel box columns in moment frames is showed to be not less than that in isolated column test, indicating that the current method of using plastic behaviors of isolated columns test is appropriate and safe.
This study also compared methods for prediction of backbone curves provided by codes and studies around the world, showing that the formulas developed by Chou and Chen (2020) is the only method that can predict maximum moment well for hollow box columns under large axial load.
The predicted backbone curves of columns were converted into material properties in nonlinear structural analysis software (PISA3D) to model the test specimens in this study.The results showed that the method mentioned above could simulate the behaviors of steel box column moment-resisting frame well.

並列關鍵字

Hollow box steel column ； Moment-resisting frame ； Seismic behavior ； Backbone curve ； Nonlinear analysis

參考文獻

ATC (2017), Guidelines for Nonlinear Structural Analysis for Design of Buildings： Part IIa – Steel Moment Frames, NIST GCR 17-917-46v2.

ASCE (2014), Seismic Evaluation and Retrofit of Existing Buildings, ASCE 41-13, American Society of Civil Engineers, Reston, VA.

ASCE (2017), Seismic Evaluation and Retrofit of Existing Buildings, ASCE 41-17, American Society of Civil Engineers, Reston, VA.

AISC (2016), Seismic Provisions for Structural Steel Buildings, ANSI/AISC 341-16, American Institute of Steel Construction, Chicago, Illinois.

AISC (2016), Specification for Structural Steel Buildings, ANSI/AISC 360-16, American Institute of Steel Construction, Chicago, Illinois.