台度磚牆剪力強度計算公式

The Shear Strength of Brick Wall of Window Spandrel

張順益(Shuenn-Yih Chang) ； 洪浩恩(Hao-En Hung)

《結構工程》 38卷2期 (2023/06) Pp. 65-82

https://doi.org/10.6849/SE.202306_38(2).0003

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。

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

並列摘要

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.

並列關鍵字

Reinforced concrete frame ； window spandrel ； pushover analysis ； failure theory of brick wall ； shear strength of brick wall of window spandrel

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