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「結構工程」季刊第148期(第38卷第2期)
「結構工程」季刊第148期(第38卷第2期)
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中文網址: 第38卷第2期 (2023)
英文網址: Vol.38 / No.2 (2023)
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第三十八卷第二期 (期別148) (112年)
第三十八卷第二期 (期別148) (112年)
| 標題 | 電熱熔渣銲儲倉口形狀對其破壞時機之影響 |
|---|---|
| 作者 | 楊鈞堯、蔡克銓 |
| 關鍵字 | 鋼箱型柱、梁柱接頭、電熱熔渣銲、SM570M-CHW 高強度鋼、喇叭形儲倉口、有限元素模型分析、鋼材破壞預測模型。 |
| 摘要 | 鋼箱型柱為傳遞梁彎矩，常使用電熱熔渣銲（Electro-Slag Welding, ESW）在柱內配置橫隔板。因施工誤差或鋼柱兩向梁深不同，而致梁翼與橫隔的高程偏心，在銲道熱影響區（Heat Affected Zone, HAZ）旁的初始縫隙尖端易發生脆性破壞。將ESW 熔填截面形狀（儲倉口）由矩形改為喇叭形，可增加熔幅但亦會提升ESW 入熱量。本研究利用SM570M-CHW 鋼材可容忍高入熱的特性，探討ESW 耐震行為。為量化研究ESW 破壞機制，現採用MM-CVGM 鋼材破壞預測模型以預測ESW 的破壞時機。先對過往曾有之2組ESW 元件單向拉伸試驗及7 組實尺寸梁柱接頭反覆載重試驗，分析顯示MM-CVGM 預測所得與試驗相差不超過1 個載重迴圈，相較舊用模型更準確且保守。本研究另再執行4 組實尺寸梁柱接頭反覆載重試驗，探討儲倉口與梁翼偏心對ESW 破壞之影響。當儲倉口由傳統矩形改為小或大喇叭形，試體由1.5%層間位移角可改善至4%才發生破壞。為有效預測大型構件受低週疲勞之破壞，本研究修改MM-CVGM 模型的破壞判斷式，藉有限元素模型中首先破壞的元素與群組，決定整體破壞時機，將此應用於4 組試體可得預測與試驗相差皆不超過1 個載重迴圈。為探討母材及銲材的韌性差異，本研究另進行圓周刻痕試片之反覆拉伸試驗，再建立有限元素模型與代表性體積單元模型分析，結果顯示，不同來源的同系列鋼材，可獲得相似的破壞曲線且誤差在10%內。母材為SM570M-CHW 時HAZ 破壞曲線斜率為ESW 之114%與CJP 之88%，三者有相同的破壞臨界值且差異在5%內；母材改為SN490C 時HAZ 的破壞臨界值即降至29%。本研究建議柱板若為SN490C 或SM570M-CHW，皆可採用喇叭形儲倉口，以有效延緩ESW 之脆性破壞。 |
| Title | Effects of chamber geometry on electro-slagwelding failure |
|---|---|
| Author | Chun-Yao Yang, Keh-Chyuan Tsai |
| Keywords | steel box column, welded moment connection, electro-slag welding,SM570M-CHW steel, flared chamber, finite element model analysis, steel fracture prediction model. |
| Abstract | In order to transfer the steel beam moment, diaphragm plates are welded inside the box column at the beam flange elevations. Electro-slag welding (ESW) is commonly used to attach the diaphragms to the column. Due to the fabrication imperfection or the frame beam depth difference, eccentricity between beam flange and diaphragm elevations may exist. This situation could lead to brittle fracture initiated at the tip of initial slit near heat affected zone (HAZ). By changing the ESW chamber from a rectangular to a flared cross section, the fusion zone can be increased, but with a price of increasing the thermal input. Considering its advantage of high heat tolerance, SM570M-CHW high strength steel column is considered. This study firstly applied the MM-CVGM fracture prediction model to the tests of two ESW component specimens and seven full-scaled steel beam-to-box column (BC) subassembly specimens conducted in previous studies. Analytical results indicate that the difference between MM-CVGM prediction and test results is no more than one loading cycle, which is more accurate and conservative than the previous model. Additionally, four full-scale BC specimens were fabricated and tested to investigate the effects of chamber geometry and column flange thickness on ESW performance. Results show that the joint with a rectangular ESW failed at the 1.5% inter-story drift ratio (IDR) cycle, while the fractures were delayed until the 4% IDR when the ESW sections were changed to a large or small flared shape. The fracture criterion of the MM-CVGM model was modified in this study. The overall failure initiation is determined by the difference of the first crack initiation between the element and the group. Applying this conditional fracture criterion to the test results, the difference between the prediction and test results is no more than one loading cycle. Circumferential-notched tensile coupon tests were conducted to investigate the ductility difference between the base and weld metals. This study utilized representative volume element models in finite element model analyses. Results show that even the steels are from different sources, very similar failure response can be observed for the same grade of steel with a difference less than 10%. Analytical results indicate that the slope of damage evolution curve of HAZ in the SM570M-CHW base metal is 114% of ESW zone and 88% of CJP zone. Three regions have the same critical damage threshold and the difference is within 5%. When the base metal is changed to SN490C, the critical damage threshold of HAZ is reduced to 29%. Based on the research results, it is recommended that the ESW chamber be considered with a flared section when grade SM570M-CHW or SN490C steel is selected for the column in order to effectively delay the ESW crack initiation. |
| 標題 | 繫筋配置對於鋼筋混凝土梁耐震性能影響之實驗研究 |
|---|---|
| 作者 | 李台光、陳正誠 |
| 關鍵字 | 鋼筋混凝土梁、繫筋、耐震性能 |
| 摘要 | 現行「混凝土結構設計規範」規定，鋼筋混凝土梁於塑性鉸區域，梁縱向鋼筋在各角隅處之梁縱向鋼筋及每隔一根梁縱向鋼筋，均須以閉合箍筋或閉合肋筋之轉角或繫筋之彎鉤作側向支撐，惟國內鋼筋混凝土工程施工實務，RC梁縱向鋼筋配置較為密集，致使難以施工。本研究針對繫筋配置對於鋼筋混凝土梁耐震性能影響，規劃4座大型鋼筋混凝土梁試體進行實驗驗證，分別為S6D試體橫向鋼筋間距為6倍最小梁縱向鋼筋直徑(D25)，且梁中間縱向鋼筋不配置繫筋；S4D試體橫向鋼筋間距為4倍最小梁縱向鋼筋直徑(D25)，且梁中間縱向鋼筋不配置繫筋；S6D-SHB試體橫向鋼筋間距為6倍最小梁縱向鋼筋直徑(D25)，梁中間縱向鋼筋配置繫筋其耐震彎鉤勾住梁底部縱向鋼筋；S6D-SHT試體橫向鋼筋間距為6倍最小梁縱向鋼筋直徑(D25)，梁中間縱向鋼筋配置繫筋其耐震彎鉤勾住梁頂部縱向鋼筋。S6D-SHB及S6D-SHT試體橫向鋼筋(3根SD280W之D10鋼筋)總圍束力與S6D試體(2根SD 420W之D10鋼筋)相同。研究結果發現：(1)負方向(梁頂部縱向鋼筋受拉及底部縱向鋼筋受壓)韌性表現，以S6D-SHB試體為最優，S6D-SHT及S4D試體次之，S6D試體為最差。S6D-SHB試體為最優，其原因在於配置中間垂直繫筋且其耐震彎鉤勾住梁底部縱向鋼筋，延緩底部縱向鋼筋受壓挫屈之效應；(2)在相同橫向鋼筋總圍束力作用下，配置外閉合箍筋及中間垂直繫筋且其耐震彎鉤勾住梁底部縱向鋼筋試體之極限層間位移角及塑性轉角較採用外閉合箍筋的試體高出5%及12%，建議施工時，接近RC梁柱接頭2倍梁深度的範圍內，先不組立底模及側模，待繫筋完成組裝後，再進行底模及側模之組立，應可解決施工困難的問題；(3)橫向鋼筋間距為4倍最小梁縱向鋼筋直徑的試體之極限層間位移角及塑性轉角較橫向鋼筋間為6倍最繫筋配置對於鋼筋混凝土梁耐震性能影響之實驗研究小梁縱向鋼筋直徑的試體相等及高出8%，RC梁橫向鋼筋間距對於RC梁耐震性能之影響並不顯著；(4)在相同橫向鋼筋總圍束力作用下，配置外閉合箍筋及中間垂直繫筋且其耐震彎鉤勾住梁底部縱向鋼筋試體之極限層間位移角及塑性轉角較採用外閉合箍筋的試體高出5%及12%，配置外閉合箍筋及中間垂直繫筋且其耐震彎鉤勾住梁頂部縱向鋼筋試體之極限層間位移角及塑性轉角較採用外閉合箍筋的試體高出2%及4%。本研究發現「混凝土結構設計規範」第15.4.3.3節RC梁於塑性鉸區域，在各角隅處之梁縱向鋼筋及每隔一根梁縱向鋼筋，均須以閉合箍筋或閉合肋筋之轉角或繫筋之彎鉤作側向支撐之規定對於RC梁耐震性能之影響並不顯著；(5)所有4座試體正向包絡線強度無明顯衰減的情形，負方向側向強度則有明顯衰減的情形，此外Pinching(收縮)效應明顯，且極限側向位移角均可達到4.0%以上，惟參考現行「鋼結構極限設計法規範及解說」第13.6.1節韌性抗彎矩構架梁柱接頭所需塑性轉角為0.03弧度，因此所有試體的韌性(塑性轉角)表現基本上皆未達耐震結構3.0% rad之所需，推測原因應為撓剪破壞所致；(6)無論是矩形或T型斷面梁柱接頭，梁頂部縱向鋼筋量一般會略大於梁底部縱向鋼筋量，因此T型梁主要破壞模式應為梁底層縱向鋼筋受壓破壞，撐開閉合箍筋及繫筋所致，而配置垂直繫筋且其耐震彎鉤勾住梁底部縱向鋼筋，也應該有延緩底部縱向鋼筋受壓挫屈之效果。 |
| Title | Experimental Study on the Effect of Crosstie Configuration on the Seismic Performance of Reinforced Concrete Beams |
|---|---|
| Author | Tai-Kuang Lee, Cheng-Cheng Chen |
| Keywords | reinforced concrete beams, crossties, seismic performance |
| Abstract | The current Building Code Requirements for Structural Concrete stipulates that in the plastic hinge zone of reinforced concrete beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used as lateral support. However, in Taiwan reinforced concrete construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large-scale reinforced concrete beam specimens were planned and fabricated to conduct experiments to verify the effect of crosstie configuration on the seismic performance of reinforced concrete beams. The transverse reinforcement spacing of S6D and S4D specimens is 6 and 4 times the minimum beam longitudinal reinforcement diameter (D25) respectively, and the longitudinal reinforcements in the middle of the beam are not enclosed with crossties. The transverse reinforcement spacing of S6D-SHB S6D-SHT specimens is 6 times the minimum beam longitudinal reinforcement diameter (D25), the longitudinal reinforcement in the middle is enclosed with crossties, and the seismic hook engages the longitudinal reinforcement at the bottom and the top of the beam, respectively. The total confining force of the transverse reinforcement of S6D-SHB and S6D-SHT specimens (3-D10 reinforcements of SD 280W) is the same as that of S6D specimen (2-D10 reinforcements of SD 420W). It is found that: (1) With respect to the seismic performance in the negative direction (the longitudinal reinforcement at the top of the beam is under tension and the longitudinal reinforcement at the bottom is under compression), the S6D-SHB specimen is the best, the S6D-SHT specimen is second, and the S4D specimen is the third. S6D specimen is the worst. It is because that the middle vertical crosstie is configured in the S6D-SHB specimen and its seismic hook engages the longitudinal reinforcement at the bottom of the beam, delaying the effect of buckling of the longitudinal reinforcement at the bottom. (2) In the same transverse reinforcement total confining force, the ultimate drift angle and plastic rotation angle of the specimen with outer closed hoop and middle vertical crosstie and its seismic hook engaging the longitudinal reinforcement at the bottom of the beam are 5% and 12% higher than those of the specimen with outer closed hoop. It is recommended that during construction, within a range close to 2 times the depth of the beam at the RC beam-column connection, the bottom and side forms are not assembled in advance, and then after the crossties are assembled, the bottom and side forms are installed to solve the construction difficulties. (3) The ultimate drift angle and plastic rotation angle of the specimen with the transverse reinforcement spacing of 4 times the minimum beam longitudinal reinforcement diameter are equal to and 8% higher than those of the transverse reinforcement spacing of 6 times the minimum beam longitudinal reinforcement diameter. The transverse reinforcement spacing of RC beams has no significant effect on the seismic performance of RC beams. (4) Under the same total confining force of transverse reinforcements, when the outer closed hoops and the middle vertical crossties are configured and the seismic hooks engage the longitudinal reinforcement at the bottom of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 5% and 12% higher than those of the specimen with outer closed hoop. When the outer closed hoops and middle vertical crossties are configured and the seismic hooks engage the longitudinal reinforcements at the top of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 2% and 4% higher than those of the specimen with outer closed hoops. This study found that in Section 15.4.3.3 of Building Code Requirements for Structural Concrete, for the plastic hinge zone of RC beams, the rule that the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used has no significant effect on the seismic performance of RC beams. (5) All four specimens have no significant attenuation in the positive lateral strength, and the negative lateral strength has significant attenuation. In addition, the pinching effect is obvious, and the ultimate drift angle can reach more than 4.0% rad. The required plastic rotation angle is 0.03 rad, so the seismic performance (plastic rotation angle) of all specimens basically does not meet the requirement of 3.0% rad for earthquake-resistant structures. It is speculated that the reason should be caused by flexural-shear failure. (6) For RC beam-column connections, the amount of longitudinal reinforcement at the top is generally slightly greater than the amount of longitudinal reinforcement at the bottom. Therefore, the main failure mode of the T-shaped beam should be the compression failure of the longitudinal reinforcement at the bottom, and the expansion of the closed hoops and crossties. The seismic hook of vertical crosstie engaging the longitudinal reinforcement at the bottom of the beam should also have the effect of delaying the compression and buckling of the longitudinal reinforcement at the bottom. |
| 標題 | 台度磚牆剪力強度計算公式 |
|---|---|
| 作者 | 張順益、洪浩恩 |
| 關鍵字 | 鋼筋混凝土構架、台度磚牆、側推分析、磚牆破壞理論、剪力強度公式 |
| 摘要 | 由先前鋼筋混凝土構架填充台度磚牆的試驗研究，發現現行台度磚牆的側向剪力強度公式並無法提供可靠的預測，進而影響側推分析的準確性。因此研究團隊在國科會研究計畫補助下，多年來陸續完成八座鋼筋混凝土構架填充台度磚牆的試驗研究。本研究首先將探討現行台度磚牆的側向剪力強度公式的缺陷，隨後提出改善公式，並利用此八座試體的反覆載重試驗結果來重新推導台度磚牆的剪力強度計算公式。現行台度磚牆剪力強度計算公式有兩個明顯的缺陷：(1) 計算公式未考慮台度磚牆高度或高寬比對剪力強度的影響以及(2) 由於未區分高、低台度磚牆，因而對於高台度磚牆的剪力強度計算公式就如同低台度磚牆一樣未納入紅磚自體劈裂強度的貢獻。依據磚牆破壞理論，磚牆強度的貢獻可能來自於紅磚與砂漿的水平介面摩擦強度，垂直灰縫的劈裂強度以及紅磚的自體劈裂強度。本文將針對上述缺陷進行改善，並重新提出台度磚牆剪力強度計算公式。在提出新台度磚牆剪力強度含待定係數的計算公式之後，利用八座試體的反覆載重試驗值經由回歸分析來擬定台度磚牆的剪力強度計算公式。為了進一步驗證此公式的可靠性，特別搜集其他研究團隊的台度磚牆剪力強度試驗值來進行比較。雖然這些試體的砌磚方式為法式砌法與新研擬公式所使用的英式砌法不同，但比對結果仍舊相當一致準確。 |
| Title | The Shear Strength of Brick Wall of Window Spandrel |
|---|---|
| Author | Shuenn-Yih Chang , Hao-En Hung |
| Keywords | Reinforced concrete frame, window spandrel, pushover analysis, failure theory of brick wall, shear strength of brick wall of window spandrel |
| Abstract | The previous experimental study of reinforced concrete frames infilled with brick wall of window spandrel revealed that the shear strength of the brick wall cannot be reliably predicted by the current computing formula. This might result in an unreliable result that is obtained from a pushover analysis. To overcome this difficulty, a series of cyclically loading tests of the eight reinforced concrete frames infilled with this type of brick walls were conducted and thus a new computing formula can be proposed for reliably predicting the shear strength of the brick wall of window spandrel. There are two drawbacks of the current computing formula for predicting the shear strength of brick wall of window spandrel: (1) the height of the infilled brick wall of window spandrel is not considered; and (2) the strength for the rupture of brick is not accounted by the current computing formula for high brick walls of window spandrel. Based on the failure modes of brick walls, the main contributions to shear strength include the horizontal friction force between the mortar and brick, the rupture of motor in vertical direction and the rupture of brick. These two drawbacks will disappear after considering the effect of the ratio of the height over width of brick walls and the rupture of brick for the high brick walls of window spandrel. After modelling the computing formula for predicting the shear strength, a regression analysis is conducted to determine the coefficients of the computing formula based on the test results of eight specimens. To affirm the feasibility of this formula, two test results that were reported in the literature are also compared. Although they adopt the Flemish bond for bricklaying and is different from the use of the English cross bond for the eight specimens for developing the new computing formula, the calculated results are still in good agreement with the test results. |
| 標題 | 三段式鋼板阻尼器耐震試驗與設計研究 |
|---|---|
| 作者 | 賴晉霆、吳安傑、李濰揚、蔡克銓 |
| 關鍵字 | 耐震間柱、鋼板阻尼器、剪力降伏、腹板加勁板、耐震設計、反覆載重試驗 |
| 摘要 | 三段式鋼板阻尼器（steel panel damper, SPD）為一種剪力消能型的耐震間柱。本研究考慮日本學者對挫屈束制加勁板設計的研究，並參考美國AISC剪力連桿梁的設計建議，提出簡化且完整的加勁板設計流程。本研究考量容量設計法並採用貼板型連接段，提出三段式SPD 的整體耐震設計流程，內容亦包含SPD 承受軸力、抗側向扭轉挫屈等設計建議。可在製造長跨寬翼斷面後，裁切成SPD 高度後再於EJ 段進行貼板，能減低SPD 的造價。利用兩組同為淨高2.6m、深1.0m、標稱降伏剪力1128kN，但消能段腹板加勁板配置不同的實尺寸貼板型三段式SPD 進行反覆載重試驗。試驗結果顯示，兩組試體受力變形反應極為相似，在層間位移角達0.04 弧度前均無明顯強度下降現象，累計塑性變形達400 以上，具極優異的韌性與遲滯消能行為。研究利用有限元素分析模型模擬試驗反應並進行參數分析；第一組分析驗證貼板型連接段須採用塞孔銲來連接疊合板與腹板，以避免彈性挫屈。第二組分析比較AISC 剪力連桿梁與本研究所提的加勁板設計方法。分析結果顯示AISC 設計方式較保守，且因雙面加勁造成用鋼量及銲接量增加，成本較高；而本研究所提設計方法可用較少的鋼量來達到延遲腹板挫屈的效果。 |
| Title | Seismic Testing and Design of Steel Panel Dampers |
|---|---|
| Author | Jin-Ting Lai, An-Chien Wu, Wei-Yang Li, Keh-Chyuan Tsai |
| Keywords | seismic stud column, steel panel damper, shear yielding, web stiffener, seismic design, cyclic loading test |
| Abstract | The 3-segment steel (shear) panel damper (SPD) can be viewed as a type of seismic stud column capable of dissipating energy through inelastic core (IC) shear deformations. In this study, the concept of capacity design is adopted to design a novel SPD with a continuous web plate and doubler plates in the elastic joint (EJ) segments. Considering the IC web buckling resisting stiffeners design guides for SPDs from Japan, and for shear links from the US, this research proposed a simplified design procedure for the IC stiffeners. Cyclic loading tests were conducted on two full-scale 3-segment SPDs with the same EJ doubler plates but different IC web stiffeners. Specimens are 2.6m high and 1.0m deep with a nominal shear strength of 1128kN. Test results show that both specimens had remarkably similar strength and hysteresis response until the 4% inter-story drift ratio was reached. The cumulative plastic deformation index was more than 400. After calibrating the finite element material model, parametric analysis results confirm that the properly deigned plug welds are required for the doubler plates in the EJs thereby delaying shear buckling. Using six additional analysis models for three different target shear deformations of 2%, 4% and 6% radians in the IC segments, it is demonstrated that AISC design specifications on shear link web stiffeners are more conservative and costly. Seismic design recommendations for the IC web stiffeners are concluded. |
| 標題 | 含挫屈束制支撐外伸臂系統耐震性能分析與設計 |
|---|---|
| 作者 | 蔡守榕、林保均 |
| 關鍵字 | 高樓層結構、外伸臂桁架系統、挫屈束制支撐、非線性反應譜分析、非線性動力歷時分析 |
| 摘要 | 此研究主要目的為進行含阻尼器外伸臂系統結構最佳化設計與探討高樓層建築之耐震性能，重點為利用外伸臂桁架系統以降低結構物之受震反應。相較於傳統型外伸臂，特別對加裝阻尼器之外伸臂系統結構進行探討，藉由阻尼器以增加結構物阻尼比達到消能效果。而此研究所使用阻尼器為挫屈束制支撐(buckling-restrained brace, BRB)，因BRB具有良好的軸拉與軸壓力發展強度，受壓時無須考量挫屈問題與良好的消能行為，故將其特殊的力學行為加入外伸臂桁架系統中，預期在小地震下因較大的彈性勁度以及面臨大地震時透過BRB的能量消散機制以減緩結構物受震反應。此研究利用OpenSees軟體建立二維分析模型，主要以配置兩組外伸臂系統做為探討目標，並將分析模型加以簡化，分別建立四種不同樓高之72、144、216、288m之簡化模型， 為了參數研究的目的， 簡化模型使用Timoshenkobeamcolumn element，以便模擬出模型從低到高，由剪力到撓曲變形的行為。分析方法主要藉由非線性反應譜分析(Response spectral analysis, RSA)進行多種結構參數組合之參數分析，包含不同的外伸臂高程及BRB與外周柱的勁度比例，且參數值皆有一定的限制，以貼近實務上的設計。並以非線性歷時分析(Nonlinear response history analysis, NLRHA )驗證其受震反應結果。探討不同樓高含阻尼器外伸臂桁架系統，滿足不同最佳化目標包括最大頂層側位移角、層間側位移角、核心結構基底剪力、核心結構傾覆彎矩和BRB消能表現，最佳設計時結構參數的組合。 |
| Title | Seismic performance and design of high-rise building incorporating buckling-restrained brace outrigger system |
|---|---|
| Author | Shou-June Tsai, Pao-Chun Lin |
| Keywords | High-rise structures, outrigger truss systems, buckling beam bracing, nonlinear response spectrum analysis, Nonlinear response yime history analysis |
| Abstract | The keen purpose of this study is to investigate the seismic performance of buildings equipped with damped-outrigger system using the buckling-restrained brace (BRB) system (BRB-outrigger) and to propose the optimal design recommendation for buildings with a different height. The numerical models with building heights of 72, 144, 216 and 288m, each contains two layers of BRB-outrigger and a 40m by 40m structural plan are analyzed using response spectral analysis (RSA) and nonlinear response history analysis (NLRHA) procedures. To get more closer to the actual reality, the member-by-member benchmark models are designed based on the seismic code requirement. In the response spectral analysis procedure, the equivalent damping ratio is computed in order to include the BRB’s inelastic response. For the main purpose of parametric study, a simplified model which will be using a Timoshenko beamcolumn element in order to capture shear-type to flexural-type lateral deformation for a lower to higher raising buildings are proposed. The dimensionless parameters that actually describe the relationships between the core structure stiffness, outrigger flexural stiffness, the axial stiffness of BRB and perimeter column in the parameter study are considered based on practical design and allowable structural sections. The optimization targets include the maximum roof drift, inter-story drift ratio, core structure base shear, core structure overturning moment and the BRB energy dissipation performance. Based on the analyzed result, the ranges of optimal design parameters vary in the different optimization targets and building heights. This study concludes with a design recommendation for building equipped with BRB-outrigger system with different building heights. |
Vol.38/No.2 (148) (2023)
第三十八卷第二期 (期別148) (112年)
| Title | Effects of chamber geometry on electro-slagwelding failure |
|---|---|
| Author | Chun-Yao Yang, Keh-Chyuan Tsai |
| Keywords | steel box column, welded moment connection, electro-slag welding,SM570M-CHW steel, flared chamber, finite element model analysis, steel fracture prediction model. |
| Abstract | “In order to transfer the steel beam moment, diaphragm plates are welded inside the box column at the beam flange elevations. Electro-slag welding (ESW) is commonly used to attach the diaphragms to the column. Due to the fabrication imperfection or the frame beam depth difference, eccentricity between beam flange and diaphragm elevations may exist. This situation could lead to brittle fracture initiated at the tip of initial slit near heat affected zone (HAZ). By changing the ESW chamber from a rectangular to a flared cross section, the fusion zone can be increased, but with a price of increasing the thermal input. Considering its advantage of high heat tolerance, SM570M-CHW high strength steel column is considered. This study firstly applied the MM-CVGM fracture prediction model to the tests of two ESW component specimens and seven full-scaled steel beam-to-box column (BC) subassembly specimens conducted in previous studies. Analytical results indicate that the difference between MM-CVGM prediction and test results is no more than one loading cycle, which is more accurate and conservative than the previous model. Additionally, four full-scale BC specimens were fabricated and tested to investigate the effects of chamber geometry and column flange thickness on ESW performance. Results show that the joint with a rectangular ESW failed at the 1.5% inter-story drift ratio (IDR) cycle, while the fractures were delayed until the 4% IDR when the ESW sections were changed to a large or small flared shape. The fracture criterion of the MM-CVGM model was modified in this study. The overall failure initiation is determined by the difference of the first crack initiation between the element and the group. Applying this conditional fracture criterion to the test results, the difference between the prediction and test results is no more than one loading cycle. Circumferential-notched tensile coupon tests were conducted to investigate the ductility difference between the base and weld metals. This study utilized representative volume element models in finite element model analyses. Results show that even the steels are from different sources, very similar failure response can be observed for the same grade of steel with a difference less than 10%. Analytical results indicate that the slope of damage evolution curve of HAZ in the SM570M-CHW base metal is 114% of ESW zone and 88% of CJP zone. Three regions have the same critical damage threshold and the difference is within 5%. When the base metal is changed to SN490C, the critical damage threshold of HAZ is reduced to 29%. Based on the research results, it is recommended that the ESW chamber be considered with a flared section when grade SM570M-CHW or SN490C steel is selected for the column in order to effectively delay the ESW crack initiation.” |
| Title | Experimental Study on the Effect of Crosstie Configuration on the Seismic Performance of Reinforced Concrete Beams |
|---|---|
| Author | Tai-Kuang Lee, Cheng-Cheng Chen |
| Keywords | reinforced concrete beams, crossties, seismic performance |
| Abstract | “The current Building Code Requirements for Structural Concrete stipulates that in the plastic hinge zone of reinforced concrete beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used as lateral support. However, in Taiwan reinforced concrete construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large-scale reinforced concrete beam specimens were planned and fabricated to conduct experiments to verify the effect of crosstie configuration on the seismic performance of reinforced concrete beams. The transverse reinforcement spacing of S6D and S4D specimens is 6 and 4 times the minimum beam longitudinal reinforcement diameter (D25) respectively, and the longitudinal reinforcements in the middle of the beam are not enclosed with crossties. The transverse reinforcement spacing of S6D-SHB S6D-SHT specimens is 6 times the minimum beam longitudinal reinforcement diameter (D25), the longitudinal reinforcement in the middle is enclosed with crossties, and the seismic hook engages the longitudinal reinforcement at the bottom and the top of the beam, respectively. The total confining force of the transverse reinforcement of S6D-SHB and S6D-SHT specimens (3-D10 reinforcements of SD 280W) is the same as that of S6D specimen (2-D10 reinforcements of SD 420W). It is found that: (1) With respect to the seismic performance in the negative direction (the longitudinal reinforcement at the top of the beam is under tension and the longitudinal reinforcement at the bottom is under compression), the S6D-SHB specimen is the best, the S6D-SHT specimen is second, and the S4D specimen is the third. S6D specimen is the worst. It is because that the middle vertical crosstie is configured in the S6D-SHB specimen and its seismic hook engages the longitudinal reinforcement at the bottom of the beam, delaying the effect of buckling of the longitudinal reinforcement at the bottom. (2) In the same transverse reinforcement total confining force, the ultimate drift angle and plastic rotation angle of the specimen with outer closed hoop and middle vertical crosstie and its seismic hook engaging the longitudinal reinforcement at the bottom of the beam are 5% and 12% higher than those of the specimen with outer closed hoop. It is recommended that during construction, within a range close to 2 times the depth of the beam at the RC beam-column connection, the bottom and side forms are not assembled in advance, and then after the crossties are assembled, the bottom and side forms are installed to solve the construction difficulties. (3) The ultimate drift angle and plastic rotation angle of the specimen with the transverse reinforcement spacing of 4 times the minimum beam longitudinal reinforcement diameter are equal to and 8% higher than those of the transverse reinforcement spacing of 6 times the minimum beam longitudinal reinforcement diameter. The transverse reinforcement spacing of RC beams has no significant effect on the seismic performance of RC beams. (4) Under the same total confining force of transverse reinforcements, when the outer closed hoops and the middle vertical crossties are configured and the seismic hooks engage the longitudinal reinforcement at the bottom of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 5% and 12% higher than those of the specimen with outer closed hoop. When the outer closed hoops and middle vertical crossties are configured and the seismic hooks engage the longitudinal reinforcements at the top of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 2% and 4% higher than those of the specimen with outer closed hoops. This study found that in Section 15.4.3.3 of Building Code Requirements for Structural Concrete, for the plastic hinge zone of RC beams, the rule that the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used has no significant effect on the seismic performance of RC beams. (5) All four specimens have no significant attenuation in the positive lateral strength, and the negative lateral strength has significant attenuation. In addition, the pinching effect is obvious, and the ultimate drift angle can reach more than 4.0% rad. The required plastic rotation angle is 0.03 rad, so the seismic performance (plastic rotation angle) of all specimens basically does not meet the requirement of 3.0% rad for earthquake-resistant structures. It is speculated that the reason should be caused by flexural-shear failure. (6) For RC beam-column connections, the amount of longitudinal reinforcement at the top is generally slightly greater than the amount of longitudinal reinforcement at the bottom. Therefore, the main failure mode of the T-shaped beam should be the compression failure of the longitudinal reinforcement at the bottom, and the expansion of the closed hoops and crossties. The seismic hook of vertical crosstie engaging the longitudinal reinforcement at the bottom of the beam should also have the effect of delaying the compression and buckling of the longitudinal reinforcement at the bottom.” |
| Title | The Shear Strength of Brick Wall of Window Spandrel |
|---|---|
| Author | Shuenn-Yih Chang , Hao-En Hung |
| Keywords | Reinforced concrete frame, window spandrel, pushover analysis, failure theory of brick wall, shear strength of brick wall of window spandrel |
| Abstract | The previous experimental study of reinforced concrete frames infilled with brick wall of window spandrel revealed that the shear strength of the brick wall cannot be reliably predicted by the current computing formula. This might result in an unreliable result that is obtained from a pushover analysis. To overcome this difficulty, a series of cyclically loading tests of the eight reinforced concrete frames infilled with this type of brick walls were conducted and thus a new computing formula can be proposed for reliably predicting the shear strength of the brick wall of window spandrel. There are two drawbacks of the current computing formula for predicting the shear strength of brick wall of window spandrel: (1) the height of the infilled brick wall of window spandrel is not considered; and (2) the strength for the rupture of brick is not accounted by the current computing formula for high brick walls of window spandrel. Based on the failure modes of brick walls, the main contributions to shear strength include the horizontal friction force between the mortar and brick, the rupture of motor in vertical direction and the rupture of brick. These two drawbacks will disappear after considering the effect of the ratio of the height over width of brick walls and the rupture of brick for the high brick walls of window spandrel. After modelling the computing formula for predicting the shear strength, a regression analysis is conducted to determine the coefficients of the computing formula based on the test results of eight specimens. To affirm the feasibility of this formula, two test results that were reported in the literature are also compared. Although they adopt the Flemish bond for bricklaying and is different from the use of the English cross bond for the eight specimens for developing the new computing formula, the calculated results are still in good agreement with the test results. |
| Title | Seismic Testing and Design of Steel Panel Dampers |
|---|---|
| Author | Jin-Ting Lai, An-Chien Wu, Wei-Yang Li, Keh-Chyuan Tsai |
| Keywords | seismic stud column, steel panel damper, shear yielding, web stiffener, seismic design, cyclic loading test |
| Abstract | The 3-segment steel (shear) panel damper (SPD) can be viewed as a type of seismic stud column capable of dissipating energy through inelastic core (IC) shear deformations. In this study, the concept of capacity design is adopted to design a novel SPD with a continuous web plate and doubler plates in the elastic joint (EJ) segments. Considering the IC web buckling resisting stiffeners design guides for SPDs from Japan, and for shear links from the US, this research proposed a simplified design procedure for the IC stiffeners. Cyclic loading tests were conducted on two full-scale 3-segment SPDs with the same EJ doubler plates but different IC web stiffeners. Specimens are 2.6m high and 1.0m deep with a nominal shear strength of 1128kN. Test results show that both specimens had remarkably similar strength and hysteresis response until the 4% inter-story drift ratio was reached. The cumulative plastic deformation index was more than 400. After calibrating the finite element material model, parametric analysis results confirm that the properly deigned plug welds are required for the doubler plates in the EJs thereby delaying shear buckling. Using six additional analysis models for three different target shear deformations of 2%, 4% and 6% radians in the IC segments, it is demonstrated that AISC design specifications on shear link web stiffeners are more conservative and costly. Seismic design recommendations for the IC web stiffeners are concluded. |
| Title | Seismic performance and design of high-rise building incorporating buckling-restrained brace outrigger system |
|---|---|
| Author | Shou-June Tsai, Pao-Chun Lin |
| Keywords | High-rise structures, outrigger truss systems, buckling beam bracing, nonlinear response spectrum analysis, Nonlinear response yime history analysis |
| Abstract | The keen purpose of this study is to investigate the seismic performance of buildings equipped with damped-outrigger system using the buckling-restrained brace (BRB) system (BRB-outrigger) and to propose the optimal design recommendation for buildings with a different height. The numerical models with building heights of 72, 144, 216 and 288m, each contains two layers of BRB-outrigger and a 40m by 40m structural plan are analyzed using response spectral analysis (RSA) and nonlinear response history analysis (NLRHA) procedures. To get more closer to the actual reality, the member-by-member benchmark models are designed based on the seismic code requirement. In the response spectral analysis procedure, the equivalent damping ratio is computed in order to include the BRB’s inelastic response. For the main purpose of parametric study, a simplified model which will be using a Timoshenko beamcolumn element in order to capture shear-type to flexural-type lateral deformation for a lower to higher raising buildings are proposed. The dimensionless parameters that actually describe the relationships between the core structure stiffness, outrigger flexural stiffness, the axial stiffness of BRB and perimeter column in the parameter study are considered based on practical design and allowable structural sections. The optimization targets include the maximum roof drift, inter-story drift ratio, core structure base shear, core structure overturning moment and the BRB energy dissipation performance. Based on the analyzed result, the ranges of optimal design parameters vary in the different optimization targets and building heights. This study concludes with a design recommendation for building equipped with BRB-outrigger system with different building heights. |
固定式及浮式離岸風機平行化結構分析及設計程式講習會
親愛的會員您好，
代轉發資訊如附檔，提供大家踴躍參加，謝謝．
活動資訊：
(一)活動時間：112年6月30日(星期五)10:00~12:00
(二)活動地點：國家地震工程研究中心-101會議室（台北市大安區辛亥路三段200號）
(三)報名網址：https://conf.ncree.org.tw/index.aspx?n=A11206300 (報名人數上限150人)
(四)費用：免費
本講習會已向行政院公共工程委員會申請技師換證積點及公務人員終身學習護照相關證書。
報名相關問題聯繫窗口：
02-66300924 林瑞綿 小姐
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中華民國結構工程學會 敬啟－05/30/2023
附件：講習會議程
2023 RC與鋼結構工程研討會
親愛的會員您好，
代轉發資訊如附檔，提供大家踴躍參加，謝謝。
活動源起：
國家地震工程研究中心（國震中心）長期結合國內外產官學研界，分別藉由國科會整合型計畫或個別合作計畫等資源，致力於建築結構新型式工法的設計與施工技術的研發，包括由鋼筋混凝土或鋼材單一營建材料或兩者複合結構系統等的新系統或新技術的開發。本次研討會特別邀請長期參與研發的研究夥伴，針對個別的研究專長，發表新型結構系統、構件或材料的研發成果、規範建議的驗證研究、或熱門工法設計與施工技術的實務與經驗。領域包括台灣New RC結構系統、創新鋼結構耐震元件、新型高性能鋼纖維混凝土的開發與應用、鋼或RC柱構件的火害議題、RC預鑄工程的設計技術、及鋼、RC或複合構件的最新設計觀念與技術等。
國震中心期待本次研討會能作為產、官、學、研討論平台，對於建築物地震工程技術，除提供最新的研究趨勢與成果外，亦可廣納各界意見，使研發方向、成果展現或規範修正議案，能更具有工程實務的應用價值。
活動資訊：
(一)活動時間：112年6月15-16日(星期四、五)
(二)活動地點：國家地震工程研究中心-101會議室（台北市大安區辛亥路三段200號）
(三)報名網址：https://conf.ncree.org.tw/indexCht.aspx?n=A11206150 (報名人數上限100人)
(四)費用：2,000元整，民國112 年6 月8 日(星期四)前截止報名。
完成報名繳費程序後，不予退費
本講習會已向行政院公共工程委員會申請技師換證積點及公務人員終身學習護照相關證書。
報名相關問題聯繫窗口：
莊勝智/sjjhuang@narlabs.org.tw
紀凱甯/knchi@narlabs.org.tw
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中華民國結構工程學會 敬啟－05/26/2023
附件：研討會DM
「隔減震建築物之設計、施工及維護管理」訓練講習會
親愛的會員您好，
代轉發資訊如附檔，提供大家踴躍參加，謝謝。
活動源起：
台灣位於地震頻繁的環太平洋地震帶上，近 30 年來台灣人民對於地震所帶來的災害已有深切的認知，對於建築物耐震性能的需求也逐漸成為購屋需求的重點。統計至今台灣已有約 200 棟隔震建築物，然而隔震建築物是否能於地震發生時發揮效果，必然與隔震層規劃設計、施工及定期維護管理有關。為使工程先進能夠對於隔減震建築物之設計、施工、元件性能測試、營運中的維護管理及修復更換有完整性的了解，本會特與日本免震構造協會、財團法人台灣建築中心、財團法人國家實驗研究院國家地震工程研究中心共同籌辦「隔減震建築物之設計、施工及維護管理」講習會，並 以台灣大學土木研究大樓之中間層隔震建築物作為點檢訓練場地。
全程參與講習之學員可取得訓練積分；如測驗合格之學員，將頒發講習證書。
活動資訊：
(一)活動時間：112年5月27-28日
(二)活動地點：國家地震工程研究中心-101會議室（台北市大安區辛亥路三段200號）
(三)報名網址：https://conf.ncree.org.tw/indexCht.aspx?n=A11205270 (報名人數上限100人)
本講習會已向行政院公共工程委員會申請技師換證積點(土木.結構.建築師)，及公務人員終身學習積點。
報名相關問題聯繫窗口：
02-86676111#194/ jackson@tabc.org.tw 單啟銓先生
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中華民國結構工程學會 敬啟－05/08/2023
橋梁先進工程技術研討會(2023)
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代轉發資訊如附檔，提供大家踴躍參加，謝謝．
簡介：
本研討會以橋梁在生命週期期間之設計施工、檢測、監測、補強、維護與管理等先進工程技術為會議主題。藉由橋梁管理養護機關及學研界專家在實際工程應用案例及最新學理的發展現況介紹，回饋產官學研各界參考，期許各項橋梁先進工程技術能精進拓展並讓實績效益持續擴散，達到控制橋梁工程品質及有效管理之目的，進而保證其設計及營運所需求的安全性與使用性，延長使用年限與提昇其服務效能。
活動資訊：
(一)活動時間：112年4月21日（星期五）8時30分
(二)活動地點：國家地震工程研究中心-101會議室（台北市大安區辛亥路三段200號）
(三)報名網址：https://conf.ncree.org.tw/IndexCht.aspx?n=A11204210 (報名人數上限100人)
本說明會已向行政院公共工程委員會申請技師換證積點(土木.結構)，及公務人員終身學習積點。
報名相關問題聯繫窗口：
02-6630-0878/shengyuan@narlabs.org.tw 蕭先生
敬祝 安好
中華民國結構工程學會 敬啟－04/14/2023
附件：
「結構工程」季刊第147期(第38卷第1期)
「結構工程」季刊第147期(第38卷第1期)
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中文網址: 第38卷第1期 (2023)
英文網址: Vol.38 / No.1 (2023)
若有任何意見歡迎 email 至 csse@csse.org.tw。
Vol.38/No.1 (147) (2023)
Vol.38/No.1 (147) (2023)
| Title | Discussion on Influence of Reinforced Concrete Beam Reinforcement Detail with Flush Outside Faces of Beams and Columns on Seismic Performance |
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| Author | Tai-Kuang Lee, Cheng-Cheng Chen |
| Keywords | reinforced 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. |
| Title | Analyses and designs of the connections jointing the new steel structure and the existing RC structure in NCREE’s office building extension |
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| Author | Yu-Cheng Lin, Ming‐Chieh Chuang, Guan-Hong Lin, Pin-Pin Deng, Keh-Chyuan Tsai, Ching-Yi Tsai, An-Chien Wu, Jui-Liang Lin |
| Keywords | seismic 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. |
| Title | Mechanical Characteristics and Testing Device Development of Headed Reinforcements for Uniaxial Tension Test |
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| Author | Ker-Chun Lin, Chen-Yu Ou, Kai-Ning Chi, Sheng-Jhih Jhuang, Wen-I Liao |
| Keywords | headed reinforcement, testing device to test single headed reinforcement in tension, slip of head part, elongation, tensile strength |
| Abstract | This 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. |
| Title | A Study on Nonlinear Dynamic Behavior of Reinforced Concrete Structures using Concentrated Plasticity Model |
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| Author | Fu-Pei Hsiao, Lyan-Ywan Lu, Hsuan-Wen Huang, Hung Cheng |
| Keywords | concentrated 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. |
| Title | Regional evaluation of resilience based on FEMA P58: a case study for nonductile reinforced concrete frames in Los Angeles |
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| Author | Peng-Yu Chen, Ertugrul Taciroglu |
| Keywords | Probabilistic 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. |