考量扭矩非線性鉸之幾何性偏心鋼筋混凝土結構物耐震評估方法之研究

國內現行耐震設計規範係在構件為韌性配筋之前提下，進行結構耐震檢核，但未必適用於現存之老舊校舍，以致無法準確掌握其耐震行為。有鑑於此，本文先以二層三跨實尺寸校舍試體之反復載重試驗結果，驗證現行規範在軟層、弱層、強柱弱梁、柱破壞模式及接頭等檢核對既有校舍結構之適用性。按照現行規範檢核所得結果，在軟層、弱層及柱破壞模式這三項理論檢核皆與試驗結果互相符合，但在強柱弱梁的檢核卻與試驗結果不同，而且梁柱接頭的檢核流程也不符既有校舍結構之行為。針對現行規範不適用於既有校舍結構耐震行為之處，本文提出修正方法，經修正後，理論檢核與試驗結果互相符合且合理。確立了耐震檢核，對於以下的側推分析，更能掌握分析結果。有鑑於現今的側推分析，均未考慮校舍偏心造成的扭轉效應，因此本文使用扭矩非線性鉸模擬其偏心所造成之扭矩效應。首先建立扭矩與扭轉角的關係，在扭矩強度是使用ACI 318-95且經過折減的開裂扭矩強度及極限扭矩強度，折減原因是因為當構件受到組合載重，剪力及扭矩是由混凝土及箍筋一起承受，把混凝土及箍筋的強度全部都給扭矩，會太高估了扭矩強度，本文提出的折減方式可以合理且保守的預測鋼筋混凝土斷面的開裂扭矩強度及極限扭矩強度。在第一階段與第二階段的勁度，本文選用Tavio和Susanto Teng簡化Hsu的開裂扭轉勁度及極限扭轉勁度，與試驗相比是合理且保守。由此就可確立扭矩與扭轉角的關係，進而建立扭矩非線性鉸。建立出扭矩非線性鉸後，用M+T+V組合載重試驗作驗證，側推曲線與試驗相比，相當接近且都在保守側。在分析空構架試體發現，樓層越高扭轉效應越明顯且面外方向會產生內力。另外也建立了一L型校舍，結果顯示出，加扭矩非線性鉸之側推曲線會更合理，也避免高估結構物之耐震能力。

關鍵字

耐震評估；偏心結構物；扭矩-扭轉角關係；扭矩非線性鉸

並列摘要

Seismic performance of existing school buildings may not be sufficient from the approach of updated codes. Development of evaluation techniques becomes very important. The criteria to investigate seismic behavior of building are suitable for structures with ductile design. Therefore, they may not be valid for the existing school buildings. In this thesis, the criteria for the prediction of soft story, weak story, strong-column-weak-beam, column failure mode and joint failure for existing school buildings are studied based on experimental data. The criteria for the prediction of strong-column-weak-beam and joint failure are modified so that they are more logical and consistent with the experimental results. The methods of pushover analyses are still not suitable for the seismic evaluation of eccentric structures. This study is to develop the torsional plastic hinges for the structural members to simulate the torque behavior. First, the torque-twist relationship is established. The cracking torque and ultimate torque strengths are computed according to ACI 318-95 and reasonable reduction in torque strengths is proposed under combination loads. Cracking and ultimate torsional rigidities originated by Hsu is adopted. They are reasonable and conservative when compared with experimental results. Torsional plastic hinge is established according to the torque-twist relationship. Experimental results of beams under combined loads of bending, shear and torsion are verified. The pushover analysis curves agree with the experimental ones. In pushover analysis of a pure frame specimen, torsional effect becomes more obvious when the number of stories increases. With the addition of torsional plastic hinge, the pushover analysis of an L-shape school building is more reasonable and overestimation of the seismic capacity of the school building can be avoided.

並列關鍵字

seismic evaluation ； eccentric structure ； torque-twist relationship ； torsional plastic hinge

參考文獻

[2] 鍾立來、葉勇凱、簡文郁、柴駿甫、蕭輔沛、沈文成、邱聰智、周德光、趙宜峰、黃世建，「校舍結構耐震評估與補強技術手冊」，國家地震工程研究中心，報告編號NCREE-08-023，台北，2000年9月。

[3] ACI Committee 318, “Building Code Requirements for Reinforced Concrete (ACI 318-95) and Commentary (ACI 318R-95),” American Concrete Institute, Detroit, 1995, pp. 146-156.

[4] Hsu, T.T.C., “Torsion of Reinforced Concrete”, Van Nostrand Reinhold Company., New York, 1984.

[5] Tavio and Susanto Teng, “Effective Torsion Rigidity of Reinforced Concrete Members,” ACI Structural Journal, V.101, No. 2, March-April 2004, pp.252-260.

[9] American Society of Civil Engineers (ASCE), Seismic Rehabilitation of Existing Buildings, Report No. ASEC/SEI 41-06, Virginia, USA, 2007.

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考量扭矩非線性鉸之幾何性偏心鋼筋混凝土結構物耐震評估方法之研究

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