鋼筋混凝土平版雙向剪力強度之研究

Study on Two-Way Shear Capacity of Reinforced Concrete Flat Plate

莊勝杰(Sheng-Jie Chuang)

指導教授 ： 黃世建

國立臺灣大學/工學院/土木工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102132

摘要

目前ACI 318-19規範針對平版之貫穿剪力強度採用斷面分析法進行評估。斷面分析法是將平版剪力與撓曲視為互相獨立之力學行為。意即定義不同臨界斷面位置，並各自檢核其強度，這對於平版力學行為之詮釋不夠完整。因此本研究將內柱支承平版當作研究對象，內容主要包含實驗與分析兩部分。
本研究實驗部分，共規劃4座平版試體，並考慮貫穿剪力強度影響參數，其中包含﹕有無配置剪力筋、不同版厚及剪力筋配置型式。藉由實驗的觀察，可歸納出平版之強度及變形與參數間之關係。
本研究分析部分，採用壓拉桿模型進行分析。由於平版為薄長形構件，除了要考慮壓桿擠碎的剪壓破壞，還需考量內部支承強度不足所造成的剪拉破壞。因此本研究提出平版之剪壓強度及剪拉強度之算法。將壓桿傾斜角度(θ)當作變數，並透過節點力平衡方式解出變數(θ)。接著進一步將剪力破壞模式區分成﹕剪拉破壞、剪壓破壞及剪力平衡破壞。另外，本研究亦針對平版之撓曲破壞，提出撓曲強度對應之剪力強度。最後，本研究建立255座平版資料庫，其中包含﹕有、無剪力筋平版；方形、圓形柱頭平版；FRP平版；撓曲、剪力破壞平版試體。利用本研究方法及ACI 318-19規範對平版資料庫進行強度預測，結果顯示，相較於ACI 318-19規範，本研究方法可獲得較準確的強度預測。

關鍵字

平版 ； 貫穿剪力強度 ； 壓拉桿模型 ； 剪壓強度 ； 剪拉強度 ； 撓曲強度

並列摘要

Currently, the ACI 318-19 code adopts the sectional method to evaluate the punching shear strength of flat plate. Sectional method considers that shear and flexure are independent force behaviors, which defines critical sections at different locations and checks their strengths respectively. This cannot explain completely the force transfer mechanism of flat plate. Therefore, this study takes the interior flat plate-column connections as the research object. The main content includes two parts: experiment and analysis.
For the experiment, the tests of 4 interior flat plate-column connections were conducted. Within the experiment, some parameters affecting the punching shear strength are considered, including: with and without shear reinforcement, different slab thickness, and the change in types of stirrup arrangement. Through the observation of the experiment, the effect of the parameters on the strength and deformation of the flat plate was investigated.
For the analysis, the strut-and-tie model is used. Since the flat plate is a slender member, not only the shear compression failure due to concrete crushing, but also the shear tension failure due to insufficient internal support should be considered. Therefore, this study proposes the calculations for the shear compression strength and shear tension strength of the flat plate. Within the calculation, The inclination angle (θ) of strut is taken as a variable. By the equilibrium of nodal forces, the variable (θ) can be solved. After that, the shear failure mode is further divided into the three kinds: shear tension failure, shear compression failure, and shear balanced failure. Besides, this study also proposes the shear strength corresponding to the flexural strength for the flexural failure of the flat plate. Finally, this study established a database of 255 flat plates, including: the slab with and without stirrups, the slab with square and circle column stub, the FRP slab, and the slab with flexural and shear failure. For verification, using this study method and ACI 318-19 code to predict the strength of flat plate in the database. Results showed that this study method can obtain more accurate strength estimations than that of the ACI 318-19 code.

並列關鍵字

Flat Plate ； Punching Shear Strength ； Strut-and-Tie Model ； Shear Compression Strength ； Shear Tension Strength ； Flexural Strength

參考文獻

ACI Committee 318 (2008). “Building Code Requirements for Structural Concrete (ACI 318-08) and Commentary (ACI 318R-08) ,” American Concrete Institute, Farmington Hills, Michigan, 520 pp.

ACI Committee 318 (2019). “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” American Concrete Institute, Farmington Hills, Michigan, 623 pp.

ASCE/SEI 41-13 (2014). “Seismic Evaluation and Retrofit of Existing Buildings (41-13),” American Society of Civil Engineers, ASCE, Reston, VA, 518 pp.

Birkle, G. (2004). “Punching of Flat Slabs: Influence of Slab Thickness and Stud Layout,” PhD thesis, University of Calgary, Calgary, Alberta, Canada, 152 pp.

British Standards Institution 8110 (1997). “Structural Use of Reinforced Concrete,” Part 1-Code of Practice for Design and Construction.