- 摘 要
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(1 山東建筑大學土木工程學院， 濟南 250100；2 山東省建筑結構鑒定加固與改造重點實驗室， 濟南 250100)
［摘要］既有建筑地下增層時，需要設置托換梁將上部豎向構件的荷載向樁基礎傳遞，該托換梁為內置H型鋼的雙梁式深受彎構件。為研究托換梁受剪承載力，設計了6個試件，進行對比試驗。試驗結果表明：6個梁均表現為剪壓破壞形態(tài)；內置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量的單截面鋼筋混凝土梁相當；支座與梁柱節(jié)點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肢箍筋比外肢箍筋承擔更多剪力。最后，基于試驗結果，建立了托換梁受剪承載力計算公式，并對托換梁受剪承載力計算結果和試驗結果進行了對比。結果表明，未置H型鋼的普通鋼筋混凝土梁計算結果和試驗結果吻合較好；對于內置型鋼的梁，受剪承載力計算結果和試驗結果平均相差百分比為18.4%，但計算結果均小于試驗結果，偏安全。
［關鍵詞］既有建筑地下增層；托換梁；受剪承載力；雙梁式深受彎構件；內置H型鋼
中圖分類號：TU375-1 文獻標識碼：A文章編號：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
*國家自然科學基金重點項目（52038006）。
作者簡介：賈強，博士，教授，Email:jiaqiang@sdjzu.edu.cn。
