第三十八卷第一期 (期別147) (112年)

第三十八卷第一期 (期別147) (112年)

標題與柱外緣切齊之鋼筋混凝土梁鋼筋細部對耐震性能影響之探討
作者李台光、陳正誠
關鍵字鋼筋混凝土梁、柱、外緣切齊、耐震性能
摘要國內建築普遍存在RC梁與RC柱外緣切齊偏心接合的情況,偏心接合RC梁之韌性尚未獲得實驗驗證。本研究針對此類國內工程實務問題,規劃4座大型鋼筋混凝土梁試體,並於內政部建築研究所材料實驗中心進行實驗驗證。本研究共製作R試體(梁主筋不偏移,箍筋為正常尺寸)、RH/SU試體(梁主筋向內偏移且箍筋為縮小尺寸,側面配置U形橫向輔助筋並以2根縱向輔助筋固定)、RH試體(梁主筋向內偏移且箍筋為縮小尺寸),以及SH/SLB試體(梁主筋向內偏移且箍筋為正常尺寸,箍筋增加2根縱向輔助筋固定)等4座試體,其中R試體做為本研究耐震性能之比較基準。研究結果發現:(1)所有試體(含3種外緣切齊的梁鋼筋配置細部)均可發展4%弧度的梁端轉角,皆能達到規範耐震要求。負方向韌性表現,以RH/SU試體為最優,RH試體次之,R試體再次之,SH/SLB試體為最差。SH/SLB試體上、下層梁主筋,皆僅有1根被箍筋角落束制,梁箍筋之角落配置縱向輔助筋,對於RC梁之耐震性能可能會造成不利的影響,因此建議RC梁箍筋之角落應配置梁主筋;(2)RH試體之一側混凝土保護層達85 mm,惟RH試體之側向強度及耐震性能皆不亞於R試體,因此實務上採用RH試體之型式,應為可接受的作法;(3)RH/SU及RH等2座試體之耐震性能皆優於R試體,惟RH試體裂縫寬度較寬且混凝土保護層剝落程度明顯較RH/SU試體嚴重,因此實務上建議採用RH/SU試體之型式。
TitleDiscussion on Influence of Reinforced Concrete Beam Reinforcement Detail with Flush Outside Faces of Beams and Columns on Seismic Performance
AuthorTai-Kuang Lee, Cheng-Cheng Chen
Keywordsreinforced concrete beams, columns, flush outside faces of beams and columns, seismic performance
Abstract        In domestic buildings, the eccentric beam-column connections with the flush outside faces of beams and columns are common, and the ductility of RC beams with eccentric connections has not been experimentally verified. In view of such domestic engineering practice problems, this study plans four large-scale reinforced concrete beam specimens, and conducts experimental verification at the Materials Experiment Center of the Architecture and Building Research Institute, Ministry of the Interior, Taiwan. In this study, the R specimen (the main reinforcement of the beam is not offset, and the stirrups are of normal size), the RH/SU specimen (the main reinforcement of the beam is offset inward and the stirrups are reduced in size, the side is equipped with U-shaped transverse auxiliary reinforcement and two longitudinal auxiliary reinforcements are fixed), the RH specimen (beam main reinforcement is shifted inward and stirrups are reduced in size), and the SH/SLB specimen (beam main reinforcement is shifted inward and the stirrups are normal size, and two longitudinal auxiliary reinforcements are arranged at the corners of the stirrup) are fabricated. The research results show that: (1) All specimens (including 3 beam reinforcement details with flush outside faces) can develop beam end rotation angle of 4% radian, which can meet the seismic requirement of the specification. For the seismic performance in the negative direction, the RH/SU specimen is the best, the RH specimen is the second, the R specimen is the third, and the SH/SLB specimen is the worst. There is only one top and bottom main reinforcement of the SH/SLB specimen, which is surrounded by the corner of the stirrup. The longitudinal auxiliary reinforcement is arranged at the corner of the stirrup of the beam, which may have an adverse effect on the seismic performance of the RC beam. Therefore, it is recommended that the corners of the stirrups should be equipped with the main beam reinforcement. (2) The concrete cover on one side of the RH specimen is 85 mm, but the results of this study show that the lateral strength and seismic performance of the RH specimen are not inferior to the R specimen. It is acceptable to use the type of the RH specimen in practice. (3) The seismic performance of the RH/SU and RH specimens is better than that of the R specimen, but the RH specimen has wider crack width and the degree of spalling of the concrete cover is obviously more serious than that of the RH/SU specimen. Therefore, it is recommended to use the type of the RH/SU specimen in practice.
標題國家地震工程研究中心新建與既有樓板接合分析與設計
作者林昱成、莊明介、林冠泓、鄧彬斌 、蔡克銓、蔡青宜、吳安傑、林瑞良
關鍵字國家地震工程研究中心、耐震設計、接頭補強、化學錨栓、有限元素模型分析、非線性反應歷時分析
摘要國家地震工程研究中心為因應發展,於2019年10月至2020年11月,在既有六層樓鋼筋混凝土(reinforced concrete, RC)辦公大樓上,增建七層樓成為十三層RC、鋼骨鋼筋混凝土與鋼結構的複合結構。本文介紹二樓至七樓新建服務核樓板及鋼梁與既有 RC 結構接合處的分析與設計。本研究以梁腹側角鋼加勁,同時考量托架有無封板的型式,探討三種接合設計,並進行一系列的有限元素分析。經Abaqus有限元素模型推估接點元素在交界面的軸向勁度為100 tf/mm,配合PISA3D結構分析軟體建立十三層增建大樓的結構模型,進行16組地震的非線性反應歷時分析,二至七樓新舊樓板採雙質心雙剛性樓板的設定,並用6自由度接點元素來分析新舊樓板交界面接頭的受力。經PISA3D歷時分析結果可得二至七樓服務核與既有 RC 結構交界處之單一梁端最大軸力以及最大層間位移角,分別為165 tf以及 1% rad。本研究以保守方式,在不考慮樓板的貢獻,以上述力量和變形作為接頭的設計需求,再對各個接合設計進行 Abaqus 有限元素分析,接頭錨栓採用只受拉之線性彈簧,另以只受壓之線性彈簧來模擬接頭端鋼板抵靠於 RC 面之邊界條件,並在梁端反曲點 3,800 mm 處同步施以軸拉 1.5 mm 與面內向上 40 mm 之位移,來模擬設計地震下之設計需求。分析結果顯示基本設計的接頭型式,直托架接合之托架腹板產生明顯剪力降伏並可觀察到錨栓受力不均的情形。三種改良方案中,比較結果後可知新增封板能使錨栓最大受力降低 35% 以上,且封板傳力使錨栓受力分布均勻的效果顯著。此外,在封板角落可切除短邊長為200 mm之等腰直角三角形低應力區塊,以利未來錨栓受震後的安全性檢查。本研究確認以雙腹側角鋼加勁及直托架封板切角式為最佳方案,除能符合設計需求,可使梁發展出韌性較好之彎矩塑鉸,並具可供未來檢視錨栓的開孔。
TitleAnalyses and designs of the connections jointing the new steel structure and the existing RC structure in NCREE’s office building extension
AuthorYu-Cheng Lin, Ming‐Chieh Chuang, Guan-Hong Lin, Pin-Pin Deng, Keh-Chyuan Tsai, Ching-Yi Tsai, An-Chien Wu, Jui-Liang Lin
Keywordsseismic design, strengthened connection, chemical anchor, finite element analysis, nonlinear response history analysis
Abstract        The existing six-story office building of the National Center for Research on Earthquake Engineering (NCREE) was extended to thirteen-story from October 2019 to November 2020. This study presents the analysis and design of the connections jointing the existing RC structure and the new steel service core from the second to seventh floors. A steel bracket, which is welded to the steel beam bottom flange and connected to the RC column using chemical anchors, was considered as the basic design of the connection to transfer the gravity shear from the steel beam. This shear connection detail could avoid the congested reinforcing bars inside the RC beam-to-column joint, however, three alternative designs using strengthened schemes are investigated in this study.
        Nonlinear response history analyses (NRHAs) using PISA3D program for the NCREE’s 13-story composite building were conducted in order to gain insight into the possible maximum seismic force and deformational demands on the connections. The features of dual mass centroids and dual rigid diaphragms for the second to seventh floors are incorporated into the PISA3D model. The 6DOF joint elements are utilized to represent the aforementioned bracketed connections on the interface. The axial push-pull stiffness of 100 tf/mm, computed from an Abaqus finite element model (FEM) analysis for the connections, is utilized for all the 6DOF joint elements. A total of sixteen sets of ground accelerations are utilized. NRHA results indicate that the maximum axial force and maximum in-plane rotation of the connection at the steel beam end are about 165 tf and 0.01 radian, respectively.
        The Abaqus FEM analyses were conducted for investigation of four connection types including the basic design and three improved designs. The FEM analysis results indicate that the beam bracket of the basic design exhibits obvious shear yielding. The uneven anchor bolt forces developed are very evident. The improved load-carry capacity and a more uniform bolt forces developed are found in the strengthened designs, such as the stiffened steel angles at the beam web and bracket with cover plate. In addition, an approximately 200×200 mm triangular region on the cover plate corner with a low stress demand is observed. Based on these connections’ FEM analysis results, this study confirms that the strengthened scheme adopts double-sided stiffened steel angles at the beam web, the straight bracket with the angular cuts on the cover plates is suitable. The strengthened scheme adopted in the project not only meets the seismic demands but also allows the inspections of the anchor bolts in the future, if necessary.
  

    

標題擴頭鋼筋單體受拉之力學特徵與試驗裝置開發
作者林克強、歐宸宇、紀凱甯、莊勝智、廖文義
關鍵字擴頭鋼筋、擴頭鋼筋單體試件拉力試驗裝置、擴頭部滑動量、伸長率、拉力強度
摘要本文主要目的在探討台灣常用擴頭鋼筋之單體試件受拉的力學特徵,並開發符合時間效益的試驗裝置。本研究進行四種鋼筋強度等級(SD 420W、SD 490W、SD 550W與SD 690)共41組之擴頭鋼筋單體受拉試驗,擴頭部包括摩擦銲、銲接螺桿、擴頭滾牙與螺紋套筒灌漿等型式。試驗之滑動量結果顯示,試驗採用0.7Py與0.95Py為加載上限值,可獲得相同的合格與否鑑識結果,其中Py為鋼筋最小規定降伏強度。摩擦銲式擴頭鋼筋幾乎無滑動量。其餘滑動量由小至大分別為:限滑擴頭滾牙式、螺桿銲接式、擴頭滾牙式、與螺紋套筒灌漿式擴頭部,其中,非螺紋套筒灌漿式擴頭部之滑動量均不大於0.2 mm。對於螺紋套筒灌漿式擴頭鋼筋,有限制滑動裝置者,只要採用適當限滑裝置且施工適當時,其滑動量多能控制在0.3 mm內;無限制滑動裝置者,其滑動量均大於0.3 mm。本研究之強度試驗結果顯示,所有試體的最大強度均能發展鋼筋規定降伏強度的1.25倍與規定抗拉強度。本研究開發完成之擴頭鋼筋單體試件拉力試驗裝置能迅速並目視架設量測設備,以獲得準確的擴頭部滑動量,且較原試驗裝置可縮短約78%的試驗時間,該試驗裝置測試目標上限為SD 690之#12擴頭鋼筋。
Title“Mechanical Characteristics and Testing Device Development of Headed Reinforcements for Uniaxial Tension Test”
AuthorKer-Chun Lin, Chen-Yu Ou, Kai-Ning Chi, Sheng-Jhih Jhuang, Wen-I Liao
Keywordsheaded reinforcement, testing device to test single headed reinforcement in tension, slip of head part, elongation, tensile strength
AbstractThis paper mainly investigates mechanical characteristics of headed reinforcements in tension popular used in Taiwan and develops a fixture for testing to effectively shorten test time. A total of 41 headed reinforcement specimens that include four types of steel grade, SD 420W、SD 490W、SD 550W and SD 690, and three main types of head part, welded head, threaded head, grouted sleeve head. Test results related to head part slip showed that upper loading bounds of 0.7Py and 0.95Py to assess head part slip can acquire the same identified results those are qualified or not. The slip results for the various head parts indicated that the slip of welded head by friction was very limit. The slips of head part with the other heads from small to large in sequence were threaded head and grouted sleeve head. For the threaded heads of the headed reinforcements, all the slips were smaller than 0.2 mm. For the grouted sleeve heads of them, the slips of head part without a restraining-slip nut were more significant than 0.3 mm, but the slips of head part with a restraining-slip nut enable to be reduced under 0.3 mm as long as using proper fabricated process. Test results also presented that the maximum tensile strengths of each specimen exceeded its minimum specified ultimate strength and 1.25 times its minimum specified yield strength. The testing device developed in this study can install measure instruments quick and visually and get reliable measure results of head part slip. It also significantly reduces 78% of testing time per piece compared with the existed testing fixture. The load capacity of the fixture is for #12 reinforcement of SD 690.
標題應用集中塑性模型於鋼筋混凝土結構非線性動態行為之研究
作者蕭輔沛、盧煉元、黃炫文、鄭弘
關鍵字集中塑性模型、RC非線性、振動台實驗、TEASDA、ASCE 41、ETABS、OpenSees、ModIMK
摘要近年來國內所發生之重大地震皆造成中高樓鋼筋混凝土建物倒塌,進而導致重大人員傷亡及財產上嚴重的損失,包含南投集集921大地震、0206高雄美濃大地震及0206花蓮大地震。有鑑於此,準確模擬中高樓鋼筋混凝土建物於地震力作用下之非線性結構反應,對於鋼筋混凝土結構之耐震研究是相當重要的課題。本文擬藉由商用軟體ETABS及美國加州柏克萊大學所開發之開放式有限元素軟體OpenSees分別建立不同塑鉸之七層樓鋼筋混凝土構架模型,以探討不同塑鉸之設定對於非線性動力歷時分析結果的影響。接著再根據七層樓鋼筋混凝土構架之振動台實驗結果,驗證何種塑鉸分析結果較接近真實結構反應,期能提供工程界於塑鉸設定方面之依據。再者,由於ETABS為商用軟體,其應用上較為受限,使用者無法自行加入新開發之材料及元素或與實驗控制系統連接進行實驗,因此本文提出將ETABS模型等效轉換至開放式有限元素軟體OpenSees之方式,期能使研究者藉由ETABS為輔助建立等效之OpenSees模型,以運用OpenSees開放式軟體之特性進行分析。
根據本文研究結果顯示,以ETABS建立由國家地震工程研究中心所開發之TEASDA塑鉸且配合Pivot遲滯模型之設定,其分析結果與七層樓鋼筋混凝土構架之振動台實驗結果最為接近。此外,根據各不同塑鉸分析結果顯示,塑鉸設定之遲滯模型不同對於分析結果影響有限,而塑鉸設定之背骨曲線不同對於分析結果才會有所影響。最後由ETABS塑鉸及OpenSees塑鉸分析比較之結果可知,本文成功驗證以ETABS模型等效轉換為OpenSees模型方式之正確性。
TitleA Study on Nonlinear Dynamic Behavior of Reinforced Concrete Structures using Concentrated Plasticity Model
AuthorFu-Pei Hsiao, Lyan-Ywan Lu, Hsuan-Wen Huang, Hung Cheng
Keywordsconcentrated plasticity model, nonlinear RC, shaking table test, TEASDA, ASCE 41, ETABS, OpenSees, ModIMK
Abstract        In recent years, some strong earthquakes, including the 921 Chi-Chi Earthquake, the 0206 Meinong Earthquake, and the 0206 Hualien Earthquake, have caused the collapse of med-to-high rise reinforced concrete (RC) buildings, and resulted in heavy casualties and severe property losses. Because of this, it is crucial to perform accurate numerical simulation for the nonlinear structural response of med-to-high rise RC buildings. This paper establishes a 7-story RC frame model with different plastic hinges using the commercial software ETABS and the open-source finite element software OpenSees developed by the University of California at Berkeley, USA. The effect of different plastic hinge settings on nonlinear time history analysis of the RC building is explored in this study. Then, based on the shaking table test results of the 7-story RC building, it is judged which plastic hinge analysis results are closer to the experimental structural response. Furthermore, since ETABS is a commercial software, its extensibility is relatively limited. In other words, users cannot add newly developed materials and elements to ETABS, nor connect ETABS with the experimental control system to conduct experiments. Therefore, this paper proposes a method to convert an ETABS model to a OpenSees model. This method will enable researchers to establish the plastic hinges for an equivalent OpenSees model with the help of ETABS, and to take the openness advantage of OpenSees software for analysis.
標題基於FEMA P58法之區域韌性評估:以美國洛杉磯非韌性鋼筋混凝土構架為例
作者陳鵬宇、Ertugrul Taciroglu
關鍵字機率式地震風險評估、區域評估、FEMA P58、非韌性鋼筋混凝土構架、增量動力分析、韌性指標
摘要都會地區房屋密集,遭遇地震時產生之性能表現係決定災損之重要依據。然而既有之結構性能評估所採用之非線性靜力法為一定量式分析(deterministic),一來無法有效地將地表運動以及結構動態反應之不確定性納入,二來其結果以結構反應參數來評估其耐震力,不利於非具工程背景之業主進行決策。另一方面,近來國際上朝向發展韌性城市(resilient city),對於結構工程師而言,如何量化房屋受震後之韌性以及進行大範圍之區域評估尚不清楚。有鑑於此,本研究提出一區域韌性評估之架構,當中依據機率式地震風險評估法(即FEMA P58),將增量動力分析與蒙地卡羅模擬結合進行災損評估,並依據評估結果量化成韌性指標(resilient index)。為示範此架構之應用,本研究以美國洛杉磯地區之非韌性(nonductile)鋼筋混凝土構架為例,透過開發之自動化建模程序完成1,452棟房屋之災損及韌性評估,當中完成了95萬筆非線性動力歷時分析。評估結果顯示在最大考量地震下的平均損失比為37.3%,震後近一年的平均韌性指標不到50%,且所有房屋恢復其原有功能需要至少三年時間。本研究藉由此案例說明,介紹FEMA P58法應用於區域評估之流程,後續期望能將此架構本土化應用於災前評估與災後應變,來提升台灣的都市韌性。
TitleRegional evaluation of resilience based on FEMA P58: a case study for nonductile reinforced concrete frames in Los Angeles
AuthorPeng-Yu Chen, Ertugrul Taciroglu
KeywordsProbabilistic seismic assessment, regional evaluation, FEMA P58, nonductile reinforced concrete frames, incremental dynamic analysis, resilient index
Abstract        Seismic damage and loss assessment are highly related to buildings’ performance. However, the current nonlinear static analysis for performance evaluation is a deterministic methodology, where the uncertainties and variation of ground motion and numerical modeling cannot be considered. Furthermore, the outcome of engineering parameters is difficult to be utilized by decision-makers who may not have engineering backgrounds. While the world is toward developing resilient city, it is still not clear to structural engineers how to quantify the seismic resilience and evaluate it for large-scale regions. Hence, this research proposes a framework for regional resilience evaluation, which is based on probabilistic seismic assessment (i.e., FEMA P58) to incorporate incremental dynamic analysis and Monte Carlo simulation for damage and loss assessment. Moreover, the outcome of the regional evaluation is used to quantify the resilience index to illustrate the ability of a city for recovering from an earthquake. To demonstrate the application of the proposed framework, 1,452 nonductile reinforced concrete frames in Los Angeles are simulated by developing an automatic modeling program. Around 950,000 nonlinear time history analyses are conducted through a supercomputer, and the outcomes are used for loss estimation and resilience quantification. The results show that the mean loss ratio for nonductile frames under maximum-considered earthquake is 37.3%, and the resilience index indicates that the city needs at least 3 years to recover. While the presented work is a US-based case study, the authors hope the framework can be extended and localized for Taiwan’s development of resilient city.