黃靚 許仲遠 高翔
摘要:通過對開槽砌塊灌孔砌體的抗剪試件的靜力試驗研究,了解了開槽砌塊灌孔砌體的試件開裂荷載、極限承載力、破壞過程和破壞特征.試驗結果表明,開槽砌塊灌孔砌體和普通灌孔砌塊砌體相比,其抗剪強度得到一定程度的提高.分析了影響灌孔砌塊砌體抗剪強度的多種因素,并根據Hoffman準則以及現行的規范公式,建立了開槽砌塊灌孔砌體的抗剪強度公式,公式的計算結果與實驗結果吻合較好.建立了開槽與不開槽砌塊灌孔砌體抗剪強度的統一表達式,結果表明,將其運用在不開槽砌塊的抗剪強度的計算中是可行的.
關鍵詞:砌體;空心砌塊;破壞機理;抗剪強度
中圖分類號:TU205 文獻標識碼:A
Abstract: 3 groups of 18 shear specimens were tested to investigate the failure processes,failure characteristics and ultimate capacity. It was shown that, due to the knocking out of the slot rib, the upper and lower core columns were connected and thus made them collaborate. As a result, the shear strength of the grouted slotted block masonry was moderately higher than that of the ordinary grouted masonry. Based on the shear mechanism of concrete block masonry, a shear strength formula of grouted slotted block masonry was built with Hoffman criteria, and a uniform shear strength formula suitable for both slotted and unslotted block masonry was proposed. The calculated values, which were generated by formula developed in this method, were in good agreement with the test results.
Key words: masonry structure; hollow block; failure mechanism; shear strength
砌體是一種歷史悠久的建筑材料,具有較強的生命力\[1\],在經濟欠發達地區仍然是最主要的結構形式之一,但傳統砌體結構存在許多問題\[2\],而配筋砌塊砌體結構則能夠在很大程度上改善傳統砌體的整體性能\[3\].在配筋砌塊砌體結構中,為方便預留用于放置水平鋼筋的水平通孔,工程中常采用肋部有開槽的混凝土砌塊,砌筑墻體時,將砌塊開槽肋敲掉便可形成橫向通孔.
目前,國外學者建立了多種剪壓復合作用下砌體抗剪強度計算式\[4\],這其中最經典的是:Turnseck以及Froeht,Borchelt等人提出的主拉應力破壞理論,Hendry和Sinha提出的庫侖破壞理論,Chinwah,Pieper,Schneider和Trautsch等人根據試驗研究提出的剪摩破壞機理.
國內方面,駱萬康等人采用剪摩理論,引入剪壓復合受力影響系數的概念,建立了砌體的抗剪強度計算式,已被我國現行砌體規范所采用\[5\].洪峰將主拉強度理論與剪摩理論相結合,提出一種新的拉摩強度理論,這種理論對剪摩和剪壓兩類破壞擬合均比較好,但缺乏對于斜壓破壞的描述\[6\].蔡勇通過最小耗能原理建立了簡捷實用的設計公式,但公式沒有下降段,且缺乏對高軸壓比狀態的描述\[7\].
然而到目前為止,國內外學者大多只研究了未開槽砌塊砌體的抗剪強度、抗壓強度、本構關系等基本力學性能,卻忽視了肋部開槽對砌體基本力學性能可能產生的影響,故其研究結論具有一定的局限性.開槽砌塊灌孔砌體的力學性能與普通灌孔砌塊砌體相比更接近工程實際,所以砌塊開槽對砌體基本力學性能的影響有進一步的研究價值.
本文對3組18個開槽砌塊灌孔砌體的抗剪試件進行了靜力試驗,以了解開槽砌塊灌孔砌體的受剪開裂荷載、受剪極限承載力,并利用Hoffman準則,對開槽砌塊灌孔砌體的抗剪強度的計算公式進行了建立,并以此為根據,建立了開槽與不開槽砌塊灌孔砌體的抗剪強度的統一表達式.
2開槽砌塊灌孔砌體的受剪破壞特征
試驗結果顯示,開槽砌塊灌孔砌體沿豎向灰縫的受剪面有兩種破壞形態:單面破壞與雙面破壞,見圖4.試驗過程中灰縫砂漿與芯柱混凝土的破壞呈現出先后性,砌體受剪試件破壞并非瞬間發生,在豎向灰縫受力開裂時,因芯柱混凝土并沒有到達抗剪承載力極限狀態,試件承載力仍在增加,呈現出一定的延性.砌體試件破壞時,除了上、下兩芯柱正截面受剪破壞外(圖5所示AB,CD截面),還會在開裂灰縫和相應一側的底部承壓面之間出現斜裂縫.大多數試件的斜裂縫的開始位置剛好便是砌塊敲掉開槽肋的地方,個別試件稍有上、下移動,且斜裂縫和底部承壓面之間大致呈60°角(圖5所示EF截面).由試驗結果所測得的開槽砌塊灌孔砌體隨著灌孔混凝土強度的變化,受剪開裂荷載和極限荷載的比值的表現為A組試件是66%~88%,B組試件是55%~71%,C組試件為53%~91%,可知,當灌孔混凝土的強度增大時,砌體受剪開裂有所推遲.
5結論
本文通過對3組18個開槽砌塊灌孔砌體試件進行的受剪試驗研究和理論分析,主要得到了以下結論:
1)開槽砌塊灌孔砌體沿通縫截面有兩種受剪破壞形態:單面破壞和雙面破壞.灰縫砂漿的破壞和芯柱混凝土的破壞具有先后性.
2)開槽砌塊灌孔砌體試件在發生剪切破壞時,會在開裂灰縫與相應一側的底部承壓面中間產生斜向裂縫,角度大致呈60°.
3)開槽砌塊灌孔砌體由于敲掉了砌塊的開槽肋,被聯通的上下芯柱混凝土能夠協同工作,使其開槽砌塊灌孔砌體的抗剪強度與普通灌孔砌塊砌體相比有一定的增大.
4)利用Hoffman準則建立用于計算開槽砌塊灌孔砌體抗剪強度的公式,其計算值與本文的試驗結果基本吻合.
5)以開槽砌塊灌孔砌體抗剪強度計算公式為基礎,統一了開槽與不開槽砌塊灌孔砌體的抗剪強度計算式,用此式計算不開槽砌塊砌體抗剪強度是可行的,其計算值與試驗結果基本吻合.
參考文獻
[1]宋力. 混凝土砌塊砌體基本力學性能試驗研究與非線性有限元分析\[D\].長沙:湖南大學土木工程學院, 2005:1-50.
SONG Li. Research and nonlinear finite element analysis on the basic mechanical properties of concrete masonry\[D\]. Changsha: College of Civil Engineering, Hunan University, 2005:1-50. (In Chinese)
[2]SUCUOGLU H, MCNIVEN H D. Seismic shear capacity of reinforced masonry piers\[J\]. Journal of Structural Engineering, 1991, 117(7): 2166-2185.
[3]XU Zipeng, HUANG Liang, WU Zhiwei. Experimental research on seismic behavior of reinforced Nblock masonry shear wall\[C\]//Earth and Space 2010 Engineering, Science, Construction, and Operations in Challenging Environments. Honolulu, Hawaii:ASCE, 2010: 2806-2820.
[4]MINAIE E, MOTA M, MOON F L, et al. Inplane behavior of partially grouted reinforced concrete masonry shear walls\[J\]. Journal of Structural Engineering, 2010, 136(9): 1089-1097.
[5]駱萬康, 李錫軍. 磚砌體剪壓復合受力動、靜力特性與抗剪強度公式\[J\]. 重慶建筑大學學報, 2000, 22(4): 13-19.
LUO Wankang, LI Xijun. Composite masonry shear pressure force static and dynamic force characteristics and shear strength formula \[J\]. Journal of Chongqing Jianzhu University, 2000, 22(4): 13-19. (In Chinese)
[6]洪峰, 王紹博. 砌體結構抗震抗剪強度分析\[J\]. 地震工程與工程振動, 2000, 20(3): 28-33.
HONG Feng, WANG Shaobo. Analysis of earth quake shear strength of masonry structures\[J\]. Earthquake Engineering and Engineering Vibration, 2000, 20(3): 28-33.(In Chinese)
[7]蔡勇, 施楚賢, 馬超林, 等. 砌體在剪―壓作用下抗剪強度研究\[J\]. 建筑結構學報, 2004, 25(5): 118-123.
CAI Yong, SHI Chuxian, MA Chaolin, et al. Study of the masonry shear strength under shearcompression action\[J\]. Journal of Building Structures, 2004, 25(5): 118-123. (In Chinese)
[8]GBJ 129-90砌體基本力學性能試驗方法\[S\]. 北京: 中國建筑工業出版社, 1990:2-20.
GBJ 129-90 The basic mechanics function experiments method standard of masonry \[S\]. Beijing: China Architecture & Building Press, 1990:2-20. (In Chinese)
[9]施楚賢.砌體結構理論與設計\[M\]. 2版. 北京: 中國建筑工業出版社, 2003:1-381.
SHI Chuxian. The theory and design of masonry structure \[M\]. 2nd. Beijing: China Architecture & Building Press, 2003:1-381.(In Chinese)
[10]RAMAMURTHY K, SATHISH V, AMBALAVANAN R. Compressive strength prediction of hollow concrete block masonry prisms\[J\]. ACI Structural Journal, 2000, 97(7): 61-67.
[11]GB 50003-2001 砌體結構設計規范\[S\]. 北京:中國建筑工業出版社, 2002:1-93.
GB 50003-2001 Code for design of masonry structures \[S\]. Beijing: China Architecture & Building Press, 2002:1-93. (In Chinese)
[12]楊偉軍. 混凝土砌體配筋剪力墻研究及砌體結構可靠性分析\[D\]. 長沙: 湖南大學土木工程學院, 2000:1-110.
YANG Weijun. Research on concrete masonry and reinforced masonry shear wall and reliability analysis of masonry structures \[D\]. Changsha: College of Civil Engineering, Hunan University, 2000:1-110. (In Chinese)
[13]黃靚, 高翔, 陳良, 等. N式砌塊砌體受剪性能試驗研究\[J\]. 湖南大學學報:自然科學版, 2009, 37(2), 14-17.
1)開槽砌塊灌孔砌體沿通縫截面有兩種受剪破壞形態:單面破壞和雙面破壞.灰縫砂漿的破壞和芯柱混凝土的破壞具有先后性.
2)開槽砌塊灌孔砌體試件在發生剪切破壞時,會在開裂灰縫與相應一側的底部承壓面中間產生斜向裂縫,角度大致呈60°.
3)開槽砌塊灌孔砌體由于敲掉了砌塊的開槽肋,被聯通的上下芯柱混凝土能夠協同工作,使其開槽砌塊灌孔砌體的抗剪強度與普通灌孔砌塊砌體相比有一定的增大.
4)利用Hoffman準則建立用于計算開槽砌塊灌孔砌體抗剪強度的公式,其計算值與本文的試驗結果基本吻合.
5)以開槽砌塊灌孔砌體抗剪強度計算公式為基礎,統一了開槽與不開槽砌塊灌孔砌體的抗剪強度計算式,用此式計算不開槽砌塊砌體抗剪強度是可行的,其計算值與試驗結果基本吻合.
參考文獻
[1]宋力. 混凝土砌塊砌體基本力學性能試驗研究與非線性有限元分析\[D\].長沙:湖南大學土木工程學院, 2005:1-50.
SONG Li. Research and nonlinear finite element analysis on the basic mechanical properties of concrete masonry\[D\]. Changsha: College of Civil Engineering, Hunan University, 2005:1-50. (In Chinese)
[2]SUCUOGLU H, MCNIVEN H D. Seismic shear capacity of reinforced masonry piers\[J\]. Journal of Structural Engineering, 1991, 117(7): 2166-2185.
[3]XU Zipeng, HUANG Liang, WU Zhiwei. Experimental research on seismic behavior of reinforced Nblock masonry shear wall\[C\]//Earth and Space 2010 Engineering, Science, Construction, and Operations in Challenging Environments. Honolulu, Hawaii:ASCE, 2010: 2806-2820.
[4]MINAIE E, MOTA M, MOON F L, et al. Inplane behavior of partially grouted reinforced concrete masonry shear walls\[J\]. Journal of Structural Engineering, 2010, 136(9): 1089-1097.
[5]駱萬康, 李錫軍. 磚砌體剪壓復合受力動、靜力特性與抗剪強度公式\[J\]. 重慶建筑大學學報, 2000, 22(4): 13-19.
LUO Wankang, LI Xijun. Composite masonry shear pressure force static and dynamic force characteristics and shear strength formula \[J\]. Journal of Chongqing Jianzhu University, 2000, 22(4): 13-19. (In Chinese)
[6]洪峰, 王紹博. 砌體結構抗震抗剪強度分析\[J\]. 地震工程與工程振動, 2000, 20(3): 28-33.
HONG Feng, WANG Shaobo. Analysis of earth quake shear strength of masonry structures\[J\]. Earthquake Engineering and Engineering Vibration, 2000, 20(3): 28-33.(In Chinese)
[7]蔡勇, 施楚賢, 馬超林, 等. 砌體在剪―壓作用下抗剪強度研究\[J\]. 建筑結構學報, 2004, 25(5): 118-123.
CAI Yong, SHI Chuxian, MA Chaolin, et al. Study of the masonry shear strength under shearcompression action\[J\]. Journal of Building Structures, 2004, 25(5): 118-123. (In Chinese)
[8]GBJ 129-90砌體基本力學性能試驗方法\[S\]. 北京: 中國建筑工業出版社, 1990:2-20.
GBJ 129-90 The basic mechanics function experiments method standard of masonry \[S\]. Beijing: China Architecture & Building Press, 1990:2-20. (In Chinese)
[9]施楚賢.砌體結構理論與設計\[M\]. 2版. 北京: 中國建筑工業出版社, 2003:1-381.
SHI Chuxian. The theory and design of masonry structure \[M\]. 2nd. Beijing: China Architecture & Building Press, 2003:1-381.(In Chinese)
[10]RAMAMURTHY K, SATHISH V, AMBALAVANAN R. Compressive strength prediction of hollow concrete block masonry prisms\[J\]. ACI Structural Journal, 2000, 97(7): 61-67.
[11]GB 50003-2001 砌體結構設計規范\[S\]. 北京:中國建筑工業出版社, 2002:1-93.
GB 50003-2001 Code for design of masonry structures \[S\]. Beijing: China Architecture & Building Press, 2002:1-93. (In Chinese)
[12]楊偉軍. 混凝土砌體配筋剪力墻研究及砌體結構可靠性分析\[D\]. 長沙: 湖南大學土木工程學院, 2000:1-110.
YANG Weijun. Research on concrete masonry and reinforced masonry shear wall and reliability analysis of masonry structures \[D\]. Changsha: College of Civil Engineering, Hunan University, 2000:1-110. (In Chinese)
[13]黃靚, 高翔, 陳良, 等. N式砌塊砌體受剪性能試驗研究\[J\]. 湖南大學學報:自然科學版, 2009, 37(2), 14-17.
1)開槽砌塊灌孔砌體沿通縫截面有兩種受剪破壞形態:單面破壞和雙面破壞.灰縫砂漿的破壞和芯柱混凝土的破壞具有先后性.
2)開槽砌塊灌孔砌體試件在發生剪切破壞時,會在開裂灰縫與相應一側的底部承壓面中間產生斜向裂縫,角度大致呈60°.
3)開槽砌塊灌孔砌體由于敲掉了砌塊的開槽肋,被聯通的上下芯柱混凝土能夠協同工作,使其開槽砌塊灌孔砌體的抗剪強度與普通灌孔砌塊砌體相比有一定的增大.
4)利用Hoffman準則建立用于計算開槽砌塊灌孔砌體抗剪強度的公式,其計算值與本文的試驗結果基本吻合.
5)以開槽砌塊灌孔砌體抗剪強度計算公式為基礎,統一了開槽與不開槽砌塊灌孔砌體的抗剪強度計算式,用此式計算不開槽砌塊砌體抗剪強度是可行的,其計算值與試驗結果基本吻合.
參考文獻
[1]宋力. 混凝土砌塊砌體基本力學性能試驗研究與非線性有限元分析\[D\].長沙:湖南大學土木工程學院, 2005:1-50.
SONG Li. Research and nonlinear finite element analysis on the basic mechanical properties of concrete masonry\[D\]. Changsha: College of Civil Engineering, Hunan University, 2005:1-50. (In Chinese)
[2]SUCUOGLU H, MCNIVEN H D. Seismic shear capacity of reinforced masonry piers\[J\]. Journal of Structural Engineering, 1991, 117(7): 2166-2185.
[3]XU Zipeng, HUANG Liang, WU Zhiwei. Experimental research on seismic behavior of reinforced Nblock masonry shear wall\[C\]//Earth and Space 2010 Engineering, Science, Construction, and Operations in Challenging Environments. Honolulu, Hawaii:ASCE, 2010: 2806-2820.
[4]MINAIE E, MOTA M, MOON F L, et al. Inplane behavior of partially grouted reinforced concrete masonry shear walls\[J\]. Journal of Structural Engineering, 2010, 136(9): 1089-1097.
[5]駱萬康, 李錫軍. 磚砌體剪壓復合受力動、靜力特性與抗剪強度公式\[J\]. 重慶建筑大學學報, 2000, 22(4): 13-19.
LUO Wankang, LI Xijun. Composite masonry shear pressure force static and dynamic force characteristics and shear strength formula \[J\]. Journal of Chongqing Jianzhu University, 2000, 22(4): 13-19. (In Chinese)
[6]洪峰, 王紹博. 砌體結構抗震抗剪強度分析\[J\]. 地震工程與工程振動, 2000, 20(3): 28-33.
HONG Feng, WANG Shaobo. Analysis of earth quake shear strength of masonry structures\[J\]. Earthquake Engineering and Engineering Vibration, 2000, 20(3): 28-33.(In Chinese)
[7]蔡勇, 施楚賢, 馬超林, 等. 砌體在剪―壓作用下抗剪強度研究\[J\]. 建筑結構學報, 2004, 25(5): 118-123.
CAI Yong, SHI Chuxian, MA Chaolin, et al. Study of the masonry shear strength under shearcompression action\[J\]. Journal of Building Structures, 2004, 25(5): 118-123. (In Chinese)
[8]GBJ 129-90砌體基本力學性能試驗方法\[S\]. 北京: 中國建筑工業出版社, 1990:2-20.
GBJ 129-90 The basic mechanics function experiments method standard of masonry \[S\]. Beijing: China Architecture & Building Press, 1990:2-20. (In Chinese)
[9]施楚賢.砌體結構理論與設計\[M\]. 2版. 北京: 中國建筑工業出版社, 2003:1-381.
SHI Chuxian. The theory and design of masonry structure \[M\]. 2nd. Beijing: China Architecture & Building Press, 2003:1-381.(In Chinese)
[10]RAMAMURTHY K, SATHISH V, AMBALAVANAN R. Compressive strength prediction of hollow concrete block masonry prisms\[J\]. ACI Structural Journal, 2000, 97(7): 61-67.
[11]GB 50003-2001 砌體結構設計規范\[S\]. 北京:中國建筑工業出版社, 2002:1-93.
GB 50003-2001 Code for design of masonry structures \[S\]. Beijing: China Architecture & Building Press, 2002:1-93. (In Chinese)
[12]楊偉軍. 混凝土砌體配筋剪力墻研究及砌體結構可靠性分析\[D\]. 長沙: 湖南大學土木工程學院, 2000:1-110.
YANG Weijun. Research on concrete masonry and reinforced masonry shear wall and reliability analysis of masonry structures \[D\]. Changsha: College of Civil Engineering, Hunan University, 2000:1-110. (In Chinese)
[13]黃靚, 高翔, 陳良, 等. N式砌塊砌體受剪性能試驗研究\[J\]. 湖南大學學報:自然科學版, 2009, 37(2), 14-17.