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(1 山東建筑大學(xué)土木工程學(xué)院， 濟(jì)南 250100；2 山東省建筑結(jié)構(gòu)鑒定加固與改造重點(diǎn)實(shí)驗(yàn)室， 濟(jì)南 250100)

［摘要］既有建筑地下增層時(shí)，需要設(shè)置托換梁將上部豎向構(gòu)件的荷載向樁基礎(chǔ)傳遞，該托換梁為內(nèi)置H型鋼的雙梁式深受彎構(gòu)件。為研究托換梁受剪承載力，設(shè)計(jì)了6個(gè)試件，進(jìn)行對(duì)比試驗(yàn)。試驗(yàn)結(jié)果表明：6個(gè)梁均表現(xiàn)為剪壓破壞形態(tài)；內(nèi)置H型鋼的鋼筋混凝土托換梁比未置H型鋼相同截面形式與配筋數(shù)量的鋼筋混凝土托換梁的受剪極限荷載提高約36.3%；雙截面鋼筋混凝土托換梁的受剪承載力與相同截面和配筋數(shù)量的單截面鋼筋混凝土梁相當(dāng)；支座與梁柱節(jié)點(diǎn)連線處的箍筋和型鋼在抗剪中起了主要作用，而支座處與梁柱節(jié)點(diǎn)附近的箍筋和型鋼起次要作用；雙截面托換梁同一截面的內(nèi)肢箍筋比外肢箍筋承擔(dān)更多剪力。最后，基于試驗(yàn)結(jié)果，建立了托換梁受剪承載力計(jì)算公式，并對(duì)托換梁受剪承載力計(jì)算結(jié)果和試驗(yàn)結(jié)果進(jìn)行了對(duì)比。結(jié)果表明，未置H型鋼的普通鋼筋混凝土梁計(jì)算結(jié)果和試驗(yàn)結(jié)果吻合較好；對(duì)于內(nèi)置型鋼的梁，受剪承載力計(jì)算結(jié)果和試驗(yàn)結(jié)果平均相差百分比為18.4%，但計(jì)算結(jié)果均小于試驗(yàn)結(jié)果，偏安全。  

［關(guān)鍵詞］既有建筑地下增層；托換梁；受剪承載力；雙梁式深受彎構(gòu)件；內(nèi)置H型鋼 

中圖分類號(hào)：TU375-1 文獻(xiàn)標(biāo)識(shí)碼：A文章編號(hào)：1002-848X(2021)13-0114-05

Experimental study on shear bearing capacity of underpinning beam for addition basement of existing buildings 

JIA  Qiang1,2,  PAN Yu1,2,  ZHANG  Xin1,2 

(1 School of Civil Engineering, Shandong Jianzhu University, Jinan 250100， China；2 Shandong Provincial Key Laboratory of Appraisal and Retrofitting in Building Structures, Jinan 250100， China) 

Abstract: When adding basement to existing building, the underpinning beam needs to be set to transfer the load of the upper vertical member to the pile foundation. The underpinning beam is a double-beam deep bending member with built-in H-shaped steel. In order to study the shear bearing capacity of underpinning beams, 6 specimens were designed and comparative tests were carried out. The test results show that the 6 beams all show the form of shear pressure failure. The shear ultimate load of reinforced concrete underpinning beam with built-in H-shaped steel is increased by about 36.3% compared with that of reinforced concrete underpinning beam without built-in H-shaped steel with the same section and reinforcement quantity. The shear bearing capacity of double-section reinforced concrete underpinning beam is equivalent to that of single-section reinforced concrete beam with the same section and reinforcement quantity. The stirrup and shaped steel at the connection between the support and the beam-column joint play major role in the shear resistance, while the stirrup and shaped steel near the support and the beam-column joint play minor role. The internal stirrups of double-section underpinning beam bear more shear force than the external stirrups. Finally, based on the test results, the calculation formula for the shear capacity of the underpinning beam was established. The calculation results of ordinary reinforced concrete beams without built-in H-shaped steel are in good agreement with the test results; for the beams with built-in shaped steel, the average percentage difference between the calculation result of shear capacity and the test result is 18.4%, but the calculation results are less than the test results, which is relatively safe. 

Keywords:addition basement of existing building； underpinning beam； shear bearing capacity；double-beam deep bending member； built-in H-shaped steel

*國(guó)家自然科學(xué)基金重點(diǎn)項(xiàng)目（52038006）。

 作者簡(jiǎn)介：賈強(qiáng)，博士，教授，Email:jiaqiang@sdjzu.edu.cn。