第三十六卷第二期 (期別140) (110年)

第三十六卷第二期 (期別140) (110年)

標題長跨桁架圍束式挫屈束制支撐之研究
作者陳雋、林昱成、吳安傑、陳律安、蔡克銓
關鍵字挫屈束制支撐、巨型斜撐、桁架圍束單元、撓曲剛度、剪力剛度、 穩定性分析
摘要跨越多樓層之挫屈束制支撐在高層建築結構中的抗震應用漸趨廣泛,桁架圍束式挫屈束制支撐(truss-confined buckling-restrained brace, TC-BRB) 為較新型之 BRB,TC-BRB 於圍束鋼管外部再配置一桁架圍束系統,由任意數量、方向與尺寸之桁架構架所構成,並與圍束鋼管共組成圍束單元來提供所需之撓曲剛度;因此其圍束鋼管與內灌水泥砂漿的撓曲剛度與斷面需求得以大幅下降。當安裝為具長跨與高軸力容量之斜撐構件時,更得以發揮減少材料用量、自重及初始凹曲等優點。本研究提出一全新型 TC-BRB,將桁架圍束系統之斷面高度由過去的等斷面改為沿 BRB 軸向變化,於跨中央最高並以正弦函數曲線向兩端漸縮,更有效率地使用材料並獲更優美之外觀。為使此新創型 BRB 方便實際工程應用,本研究建立穩定性理論模型與耐震設計方法並進行相關實驗與數值驗證。先提出桁架圍束系統等效撓曲剛度與剪力剛度計算方式,再建立穩定性理論模型。考量剪力效應計算 TC-BRB 之整體彈性撓曲挫屈強度(Pcr);並再考量初始缺陷與材料非線性行為來計算整體挫屈破壞強度(Plim)。本研究並藉 ABAQUS 有限元素模型分析進行數值驗證,結果顯示理論模型在圍束單元的 Pcr 計算上,誤差小於 10%;而於整體 TC-BRB 的 Pcr 計算上,誤差更小於 3%。為驗證理論並評估 TC-BRB 之實際遲滯消能行為,本研究第一階段設計並新造兩組具不同桁架圍束系統型態、1/5 縮尺總長 6.3 米、100 噸級之 TC-BRB 試體,利用國家地震工程研究中心多軸向試驗系統執行反覆加載試驗。理論模型考量殘餘應力的效應後,預測所得 Plim 與試驗結果的誤差小於 6%;實驗證實本研究所建理論模型於穩定性預測之準確性,更證實本研究所提之設計方法與檢核程序的可靠性。為觀察 TC-BRB 更嚴峻的耐震消能與穩定性表現,本研究第二階段再設計兩組 TC-BRB 試體並提高其整體穩定性容量,理論預測的 Plim 與試驗所得結果兩者誤差小於 7%,再次確認所提理論模型之準確性;本文提供 TC-BRB 之耐震設計流程與範例以供參考。
TitleLong-Span Buckling-Restrained Braces using Truss-Confined Restrainers
AuthorChun Chen, Yu-Cheng Lin, An-Chien Wu, Lu-An Chen, Keh-Chyuan Tsai
Keywordsbuckling-restrained brace, mega brace, truss-confined restrainer, flexural rigidity, shear rigidity, stability analysis
AbstractLong span buckling-restrained braces (BRBs) are getting popular for applications in seismic tall buildings. Recently, a novel type of BRB, namely the truss-confined BRB (TC-BRB) with a constant-depth truss built into the restrainerhas been investigated. The TC-BRB’s restrainer is constructed by attaching an additional truss system composed of several steel open-web truss frames outside the central steel casing in order to develop the overall restraining rigidity. Thus, the cross-sectionof the central steel casing and the weight of the infilled mortar in the TC-BRB can be significantly reduced in comparison with the conventional BRBs. The initial crookedness caused by the BRBs’ self-weight can also be reduced in the cases of long-span and large axial capacity BRB designs. This study investigates a new type of TC-BRB using a varying-depth truss system in the restrainers. This type of TC-BRB could save construction material and achieve the structural aesthetic more effectively than those using the constant-depth trusses. In this study, stability analytical model and seismic design procedures are developed and verified. Key mechanical properties including equivalent flexural rigidity and shear rigidity of the truss system are firstly presented. It is illustrated that the TC-BRBs’ elastic flexural buckling strength (Pcr) can be satisfactorily computed by incorporating Timoshenko shear effect into the classical stability theory. TC-BRBs’s buckling failure strength (Plim) can be further computed by considering the initial imperfections and inelastic material property.Abaqus finite element model (FEM) analysis results indicate that the proposed analytical model can satisfactorily predict the restrainers’ Pcr with errors less than 10%; and predict the TC-BRBs’ Pcr with errors less than 3%. In the first phase experiment, two 1/5-scale TC-BRB specimens, each of 6.3m long with the 1016-kN nominal yield strength anda constant- or varying-depth truss design, were tested in NCREE. Cyclic test results confirm that the Plim of the two TC-BRB specimens can be accurately predicted using the proposed analytical model with errors less than 6% when the effects of residual stresses in the truss members are considered. In the second phase experiment, two additional specimens were fabricated with significantly increased stability capacities. Cyclic test results show that the Plim of these two specimens can also be accurately predicted with the errors less than 7%, further confirm the reliability of the proposed analytical model. The TC-BRBs’ experimental performance also suggests that the proposed design procedures are generally conservative and practical. This study concludes with the recommendations, produres and examples on the seismic design of the proposed TC-BRBs using the constant- or varying-depth trussses.
標題非定值軸力作用下含組合繫筋 RC 柱之耐震性能
作者李台光、陳正誠
關鍵字組合繫筋、搭接長度、軸拉力、RC柱、耐震性能
摘要組合繫筋為由兩支一端為180度彎鉤另一端為直線的J形鋼筋搭接組合而成。本研究完成4座大尺寸鋼筋混凝土柱試體之反復側向載重試驗,探討非定值軸力作用下含組合繫筋RC柱之耐震性能。研究結果顯示:(1)非定值軸力作用下,使用180度彎鉤一體繫筋(兩端使用180度彎鉤之一體繫筋)之試體承受軸壓力之韌性(塑性轉角)表現最佳,使用組合繫筋之試體次之,使用傳統繫筋(一端具有135度彎鉤,而另一端為90度彎鉤之繫筋)之試體韌性表 現最差;(2)不論使用組合繫筋、180度彎鉤一體繫筋或傳統繫筋之RC柱試體,承受軸拉力之韌性表現優於承受軸壓力之韌性表現;(3)僅承受軸壓力之柱,當柱軸力比小於30%時,可採用組合繫筋取代傳統繫筋;(4)建築結構內柱承受較大之軸壓力,當柱在地震過程中僅承受軸壓力,且柱軸力比大於30%時,此時使用組合繫筋不但可以合乎規範要求且施工容易;(5)當柱在地震過程中承受反復軸力(即軸壓力及軸拉力)時,一般而言此種情形之 柱軸力比小於30%,此時可以採用組合繫筋取代傳統繫筋。
TitleThe seismic performance of reinforced concrete columns using the lap-spliced crosstie with various axial load
AuthorTai-Kuang Lee, Cheng-Cheng Chen
Keywordslap-spliced crosstie, lap splice length, axial tension, RC columns, seismic performance
AbstractA lap-spliced crosstie consists of two J-shaped steel bars (rebars) that have a straight end and an end featuring a 180° hook. In this study, the cyclic lateral load test of four large-scale reinforced concrete columns with axial force proportional to the lateral force was conducted to discuss the seismic performance of RC columns with lap-spliced crossties and investigate the axial tension load effect. The research results are presented as follows: (a) The seismic performance of the specimens that adopted lap-spliced crossties is superior to that of the specimen using conventional crossties and worse than that of the specimen using crossties featuring a 180° hook on the two ends. (b) The ductility of RC columns comprising lap-spliced crossties, crossties featuring a 180° hook on the two ends and conventional crossties under axial tension is superior to that under axial compression. (c) For RC columns under axial compression, when the axial force ratio is less than 30%, lap-spliced crossties can be used instead of conventional crossties. (d) The inner columns of the building structure are subjected to large axial compression. When the columns are only subjected to axial compression during the earthquake, and the column axial force ratio is greater than 30%, the use of lap-spliced crossties can not only meet the ACI design requirements, but also facilitate the construction. (e) When the columns are subjected to repeated axial forces (axial compression and axial tension) during the earthquake, generally speaking, the column axial force ratio in this case is less than 30%. In this case, lap-spliced crossties can be used to replace conventional crossties.
標題自來水配水池結構耐震評估之載重需求
作者翁元滔、劉季宇、沈文成、林敏郎、李昭賢、鍾立來
關鍵字自來水設施、耐震評估、配水池
摘要進行池狀結構之耐震評估與分析程序時,須先估算其所須考慮的靜載重、活載重、土壤載重、流體載重、溫度載重及地震載重,其中地震載重又可分成地震引致流體動態載重、土壤動態載重及構體本身之地震力等,而地震引致流體之動態載重又可分成流體衝擊模態載重、流體對流模態載重、流體垂直振動引致之水平動態載重等;其次,地震引致土壤之動態載重又可分成土壤主、被動土壓力等;另外,池狀結構構體本身亦應考慮其垂直地震力及池牆本身之側向慣性力。本研究針對國內常見的池狀結構的載重需求估算方式與耐震評估流程進行研討,俾使其耐震評估與分析程序更加完備。
TitleLoad demand assessment of liquid storage tank in water supply facilities
AuthorYuan-Tao Weng, Gee-Yu Liu, Wen-Cheng Shen, Min-Lang Lin, Lap-Loi Chung, Chao- Hsien Li
Keywordswater supply facilities, seismic evaluation, liquid storage tank
AbstractWhen carrying out the seismic evaluation and analysis procedure of the liquid storage tank, the static load, live load, soil load, fluid load, temperature load and seismic load must be estimated first. The seismic load can be divided into earthquake-induced fluid dynamic load, dynamic load of the soil and the seismic force induced by the self-weight of the structure. Firstly, the dynamic load of the fluid caused by the earthquake can be further divided into the fluid impulsive modal load, the fluid convective modal load, and the horizontal dynamic load caused by the vertical vibration of the fluid. Secondly, the soil dynamic load caused earthquakes can also be divided into active soil pressure and passive soil pressure. In addition, the vertical seismic force of the liquid storage tank and the lateral inertial force of the tank wall should also be considered. This study focuses on load demand assessment methods and seismic evaluation process for the common pool-like water tank structure in Taiwan to make the seismic evaluation and analysis procedures more feasible and reasonable.
標題跨斷層橋梁之地震反應研究
作者洪曉慧、何蓮桂、何宜哲、莊清鏘、黃仲偉
關鍵字跨斷層橋梁、非線性動力歷時、多支承輸入、地表位移輸入
摘要目前橋梁耐震規範主要是透過放大係數來考慮近斷層效應,對於跨斷層 橋梁並無相關的規定。然而跨斷層橋梁在斷層線兩側由於會因地表相對錯動而導致不同的變形趨勢,因此在數值模擬上必須採用多支承非同步輸入,計算橋梁模型在地震作用下的結構地震反應。本研究之目的在建立以地表位移輸入法為基礎之多支承地震輸入方式,用以探討跨斷層橋梁受地震作用之反應。首先以近斷層地震的地表加速度歷時經數值積分得到對應的地表位移歷時,利用多支承位移輸入方式進行非線性動力歷時分析來模擬跨斷層橋梁的地震反應。並進一步比較地表位移分配方式、斷層穿越角度、橋面板支承形式等對於跨斷層橋梁受震反應之影響。數值模擬結果顯示非同步輸入地震歷時會使橋梁結構產生局部較大變形與內力;同步輸入地震歷時則會使橋梁結構產生較大的絕對加速度。此外,本文就位移的分配方式區分為絕對錯位和相對錯位兩種,數值結果顯示在內力計算的部分,相對錯位與絕對錯位所得之最大值差異不大;但變形的部分,絕對錯位所得之最大值往往高於相對錯位所得之最大值。模擬同時顯示斷層水平角45度的作用下,對於柱底扭矩會產生較明顯的放大,但其餘物理量會小於斷層水平角90度的作用。最後,本文依主梁與柱頂接合處不同的邊界條件,將橋型分為連續橋、簡支梁橋和構架橋等三種。構架橋與連續橋的最大歷時反應相當接近,簡支梁橋各項物理量的最大歷時反應相較於連續橋可能增大或減少。
TitleSeismic Performance of Crossing–fault Bridges
AuthorHsiao-Hui Hung, Lian-Gui He, Yi-Che Ho, Ching-Chiang Chuang, Chang-Wei Huang
KeywordsCrossing-fault bridge, nonlinear time history, multiple excitation, ground displacement input
AbstractThe influences of near-fault earthquakes are taken into account only by the magnification factors in the seismic design code for highway bridges. There are no related specifications about crossing-fault bridges in the design code. However, cross-fault bridges which are subjected to different ground motions at opposite sides of the fault line suffer more attacks in earthquakes. In this study, the seismic responses of cross-fault bridges are simulated with the multiple-excitation method and solved by nonlinear dynamic time history analyses. The displacement time history of each excitation is obtained by integrating the acceleration time history of a near-fault ground motion. The influences of the velocity impulse and residual displacements of near-fault earthquakes on the seismic responses of cross-fault bridges are discussed. In addition, the effects of the boundary conditions of the bridge deck and the angle between the bridge and fault line on the seismic responses of cross-fault bridges are also elaborated here. Numerical results demonstrate that the multiple-excitation simulation obtained larger local deformation and internal forces. On the other hand, the single-excitation simulation obtained larger absolute acceleration. Moreover, the ground displacements from integration are further divided into absolute displacements and relative displacements, which are assigned to the ground motions at opposite sides of the fault line. Numerical results show that there are no obvious differences on internal forces between these two displacement distributions. However, the absolute displacement generates larger member deformation. Moreover, the torsions at the bottom of bridge columns are magnified when the fault angle is 45°. Finally, the influences of different boundary conditions between bridge slabs and columns on the seismic responses are investigated. The seismic responses of rigid connections are similar to those of pin connections while the seismic responses of simply supported bridges have different characteristics
標題不規則橋梁機率式耐震與倒塌風險評估之研究
作者劉光晏、呂依涵
關鍵字橋梁、勁度不規則、基樁裸露、土壤彈簧、機率式倒塌評估
摘要本研究探討既有群樁基礎橋梁,因沖刷導致基礎裸露前、後之耐震性能及倒塌機率。首先,針對土壤結構互制行為進行實驗與分析比較。根據群樁基礎單柱結構之雙軸向大型振動台實驗結果,比較美國石油協會(API )、日本道路橋示方書(JRA)及本研究之等值線性土壤彈簧法。研究結果顯示,在綜合考量時間成本與結果準確度下,API土壤彈簧法是較佳之樁土互制模擬方式。爰此,將API土壤彈簧應用至一座四跨全橋模型,採用增量動力分析法(IDA)並參考FEMA P58流程,探討不同橋基裸露程度之破壞模式、構件轉角韌性容量與不同等級地震之耐震能力與破壞機率,最後再與公路橋梁耐震評估與補強設計規範草案(2018年版)之靜力側推分析法進行比較。案例分析顯示,FEMA P58要求等級III地震作用下倒塌機率小於 10%,對於橋梁結構過於嚴格。短柱位置之樁基礎發生裸露時,對整體耐震性能有明顯降低。採用側推分析進行勁度不規則橋梁之耐震能力評估時, 其結構反應較動力分析有不保守的疑慮。
TitleProbabilistic Assessment of Seismic Performance and Collapse Risk for Irregularly Bridge
AuthorKuang-Yen Liu, Yi-Han Lu
KeywordsScouring Effect, Soil Spring, Group Pile Effect, Probabilistic Assessment Method, Collapse Risk Analysis, Incremental Dynamic Analysis, Static Pushover Analysis
AbstractThis study investigates the seismic performance and collapse risk of a group pile foundation irregularly bridge after scouring, which use API soil spring method to build a group pile foundation, four-span bridge models, and use probabilistic assessment to discuss the seismic performance due to different scouring places. This methodology was presented by previous researcher. For numerical analysis, this study uses SAP2000 to do incremental dynamic analysis (IDA). Afterward, based on the result, also establish fragility curve considering IO, LS, and CP performance. This study also uses pushover analysis to evaluate the seismic performance of bridge after scouring. The result shows the first yielding point for group pile will appear at the top of the pile. Second, Seismic performance for the bridge will have the greatest influence when scouring was taken place at the pier which has the biggest stiffness difference compare to its nearby pier. Last, pushover analysis for irregularly bridge may underestimate its reaction compare to nonlinear time history analysis. All in all, this simplified probabilistic procedure can be used as a reference for future seismic performance evaluation for bridges.