含邊界構材之鋼板混凝土複合剪力牆側力位移曲線模型之研究

Experimental and Analytical Studies on the Lateral Load-Displacement Curves of Shear-Critical Steel-Plate Concrete Composite Walls with Boundary Elements

詹家昕(Chia-Hsin Chan)

指導教授 ： 黃尹男

國立臺灣大學/工學院/土木工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802739

摘要

鋼板混凝土複合牆(Steel-plate concrete composite wall，簡稱SC牆)具有高勁度與高強度之特性，主要應用於核能設施結構及超高樓核心筒系統。現今美國設計規範AISC N690s1-15 (2015)及AISC 341-16 (2016)提供此類結構牆平面內剪力強度之預測公式為假設牆體受純剪下之行為所推導而得，然規範預測公式中並未考慮牆體高寬比對剪力強度之影響。在實務應用方面，SC牆並非僅受純剪之作用，其行為應須考量撓曲與剪力互制之影響；另一方面，SC牆兩端通常具有與其垂直相接猶如邊界構材的另一向牆體，且邊界構材將使SC牆整體撓曲強度大幅提升，進而使牆體破壞模式以剪力破壞所主控。因此，含邊界構材之SC牆平面內剪力強度的預測是一個重要的議題。
　　目前含邊界構材之SC牆平面內剪力強度預測的相關研究中，各預測模型針對高寬比對剪力強度之影響的看法不一，且經由試驗結果評估後皆尚未能有效掌握其影響，再者，設計規範尚未提供建立側力位移曲線之建議公式。因此，本研究集中討論含邊界構材之SC牆的行為，探討「高寬比」對其剪力強度之影響，發展一套具物理意義並能有效掌握高寬比影響之預測模型，另提出了兩種方法建立含邊界構材之SC牆側力位移曲線。
　　本研究進行兩座含邊界構材之SC牆擬靜態反覆載重試驗，從綜合文獻試驗研究與本試驗研究之不同系列試驗結果中，可得到牆體高寬比小於一定值時，高寬比對剪力強度之影響較為顯著，而高寬比大於一定值時，高寬比對剪力強度之影響就較不為顯著。以有限元素分析結果之混凝土最小主應力場比對試驗結果中混凝土破壞現象，從中假設混凝土可能之傳力機制，並將此假設針對Booth et al. (2015)預測模型進行修正，同時將高寬比對剪力強度之影響納入考量，再經由簡化與有限元素參數分析結果發展剪力強度預測模型，且與現有之預測模型進行比較，驗證結果顯示本研究建議之預測模型可合理保守估計且能夠有效掌握高寬比影響。使用Epackachi et al. (2015a)提出之簡化分析法以及PISA3D模型分別建立含邊界構材之SC牆側力位移曲線，透過有限元素分析結果之初始勁度及試驗結果之最大側推強度進行驗證，兩者皆可有效預測SC牆在2.0%層間位移角內的側力位移曲線。

關鍵字

鋼板混凝土複合牆 ； 邊界構材 ； 剪力強度 ； 有限元素分析 ； 側力位移曲線

並列摘要

Steel-plate concrete (SC) composite wall has high stiffness and high strength. They are mainly used in safety-related nuclear facilities and high-rise structural systems. Currently, AISC N690s1-15 (2015) and AISC 341-16 (2016) provide equations which are based on the behavior of SC walls subjected to pure in-plane shear to predict the in-plane shear strength of SC wall. Nevertheless, both AISC N690s1-15 (2015) and AISC 341-16 (2016) neglect the effect of aspect ratio (height-to-length). In practical application, a SC wall is affected not only by pure in-plane shear behavior but also by in-plane flexure behavior. As a result, the effect of flexure-shear interaction should be considered. On the other hand, a SC wall is very often connected with perpendicular SC walls at the ends. The perpendicular walls become the boundary elements of the longitudinal wall. Since the boundary elements can provide additional overturning moment resistance to the system, the failure mode of SC walls with boundary elements becomes shear failure. Therefore, the prediction of in-plane shear strength of shear-critical SC walls with boundary elements is one of the significant issues.
　　Recently, the studies of in-plane shear strength prediction of SC walls with boundary elements state different opinion of the effect of the aspect ratio. Furthermore, AISC N690s1-15 (2015) and AISC 341-16 (2016) do not offer the equation of lateral load-displacement curves. Consequently, this study aims to discuss the behavior of shear-critical SC walls with boundary elements and the impact of aspect ratio of a shear-critical SC wall on its strength. In addition, this research constructs a model of shear strength prediction which can dominate the effect of aspect ratio and provides two methods for building lateral load-displacement curves.
　　In the experimental program, two large-size spcimens were tested under displacement-controlled cyclic loading. From previous literatures and the test results of this research, it is clear that when aspect ratio is under certain value, the impact of aspect ratio on the shear strength is more noticeable and vice versa. By comparing the concrete minimum principal stress results from finite element method analysis with the concrete failure results from experiment, the possible mechanism of infilled concrete is obtained. To sum up, the shear strength prediction model in this research is modified from the model of Booth et al. (2015) and it takes the effect of the aspect ratio into consideration. Moreover, the prediction model is simplified by observing the analytical results of LS-DYNA. The benchmarked finite element models are then used to conduct a parametric study, which investigates the effects of wall aspect ratio, reinforcement ratio and uniaxial concrete compressive strength on the depth of the concrete compression zone. The verification results shows that the prediction model in this study is more accurate than any other prediction models from seleted literatures. Lateral load-displacement curves of shear-critical SC walls with boundary elements are developed by simplified analytical models from Epackachi et al. (2015a) and by PISA3D pushover models. Both predicted curves match the initial stiffness from finite element method analysis and the experimental peak lateral strength within a drift ratio of 2.0%.

並列關鍵字

Steel-plate concrete composite wall ； Boundary element ； Shear strength ； Finite element method analysis ； Lateral load-displacement curve

參考文獻

鄭與錚 (2016)。有邊界構材之鋼板混凝土複合牆之耐震行為與試驗研究。國立臺灣大學工學院土木工程學系碩士論文，臺北市。

ACI 318-14 (2014). “Building Code Requirements for Structural Concrete and Commentary.” ACI 318-14, American Concrete Institute, Farmington Hills, Michigan.

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

AISC N690s1-15 (2015). “Specification for Safety-Related Steel Structures for Nuclear Facilities.” AISC N690s1-15, American Institute of Steel Construction, Chicago, Illinois.

Akita, S., Ozaki, M., Niwa, N., Matsuo, I., and Hara, K. (2001). “Study on Steel Plate Reinforced Concrete Bearing Wall for Nuclear Power Plants (part #2). Analytical Method to Evaluate Response of SC Walls.” Transactions, SMiRT-16, International Association for Structural Mechanics in Reactor Technology (IASMiRT), North Carolina State University, Raleigh, NC.