工程科学与技术2025，Vol.57Issue(6)：213-221,9.DOI:10.12454/j.jsuese.202301011
"L"形槽不出筋叠合板承载性能足尺试验研究
Experimental Study on Bearing Capacity of Full-scale Composite Slabs with L-shaped Rabbet
摘要
Abstract
Objective Traditional composite slabs require protruding reinforcement bars in the prefabricated base plate during production to ensure the integ-rity of the interface between joints and beam-panel connections.However,these protruding bars hinder the handling and stacking of components,adversely affecting on-site construction and component quality.Therefore,this study proposes a construction method for composite slabs with an L-shaped rabbet that eliminates the need for protruding reinforcement bars. Methods This study conducted static loading tests on six full-scale floor slab specimens with end beams to investigate the effect of the L-shaped rabbet end design method on the integrity of beam-panel connections and the bearing capacity of composite slabs.The specimens consisted of three composite slabs with L-shaped rabbets(design method one),two traditional composite slabs,and one cast-in-place solid slab with the same dimensions.The L-shaped rabbet composite slabs served as the experimental group,while the remaining slabs were designed traditionally and served as control groups 1 and 2,respectively.The study compared the load-bearing capacity and crack resistance of the new slabs.The loading was applied by stacking weights,with each weight block weighing 1 ton(900 kg).Each floor slab accommodated up to nine weight blocks in a single layer.The loading sequence followed a centrally symmetrical pattern to ensure even stress distribution during testing.The measurement pa-rameters during the test included:1)the number of weight blocks applied;2)vertical displacement at the mid-span and on the upper part of beams,and horizontal displacement at the lower part of beams;3)strain of reinforcing bars under stress;and 4)crack width at the mid-span and at the interface between the slab and beams.Strain gauges were attached to the reinforcing bars on the upper and lower surfaces of the composite slabs.Displacement meters were installed at the slab ends,mid-span,along the beam edges,and at the top.Crack depth and width were observed using a crack depth-width gauge under various loading conditions.Instruments such as strain acquisition devices,high-precision displacement me-ters,and crack observation tools were utilized to collect data from critical areas of the specimens.These included strain on L-shaped reinforce-ment at the ends,strain on protruding reinforcement at the ends of traditional composite slabs,deflection at the mid-span of composite slabs,and crack widths and spacings at the mid-span.These data provided a detailed basis for analyzing the overall performance of the floor slabs and the lo-cal performance of steel and concrete components. Results and Discussions Upon analyzing the experimental results,the study evaluated the number,spacing,and width of mid-span cracks,as well as the width of end cracks,as observation indicators.The crack development process in each group of slabs was similar.Cracks initially ap-peared at the locations of maximum bending moments at the slab ends and mid-span.As the load increased,both the number and width of mid-span cracks increased continuously,with smaller crack spacing and transversely extending cracks,exhibiting typical flexural failure characteris-tics.Regarding the number of cracks,the new slabs had an average of 13.3 mid-span cracks,close to the 14 cracks observed in traditional slabs.In terms of crack spacing,the average spacing for the new slabs was 10.96 cm compared to 9.275 cm for the traditional slabs,indicating a small difference.This finding indicated that,compared to traditional slabs,the new end construction did not reduce the bearing capacity at the mid-span.Regarding crack width at the slab ends,under a uniformly distributed load of 27.9 kN/m2,the end crack width at each sampling point indi-cated that the new slabs exhibited similar crack widths to traditional slabs and performed significantly better than the cast-in-place slabs.This similarity was evident from the crack width data and the consistent changes in the curve slopes between the two slab types,confirming that the L-shaped rabbet end design provided comparable overall integrity at the beam-panel connections to that of the traditional protruding reinforcement method in composite slabs.Regarding deflection,the mid-span deflection was considered the representative value.The development of deflection in the new slabs was similar to that of the traditional slabs.The rate of deflection increase in the new slabs was slightly lower than that in tradi-tional slabs,and the deflection at the limit state of bearing capacity was also lower,while the cast-in-place slab demonstrated the lowest stiffness.Based on a comprehensive analysis of deflection and cracking behavior,the end construction with L-shaped reinforcement did not significantly af-fect the bending stiffness at the mid-span of composite slabs.Regarding strain,similar to traditional reinforcement,the L-shaped reinforcement experienced minimal compressive stress during normal use,particularly before concrete cracking,and contributed little to the bending capacity at the member ends.As the height of the compressed zone decreased,the L-shaped reinforcement at the ends began to bear tensile stress.In the later stages of loading,both the L-shaped reinforcement in the new slabs and the protruding reinforcement in traditional slabs yielded,fully utilizing the load-bearing capacity of the reinforcement.The design of the L-shaped rabbet compensated for the potential reduction in bond strength caused by the shorter length of the L-shaped reinforcement. Conclusions The width and distribution of end cracks in the new slabs are highly similar to those in traditional slabs and significantly better than those in cast-in-place slabs using the L-shaped rabbet during the loading process.This finding indicates that the L-shaped end design method pro-vides sufficient reliability in beam-panel connections.The L-shaped bend restricts relative slippage between the reinforcement and the concrete,ensuring a stable connection between the slab end and the main beam.It compensates for the potentially low bond strength caused by the shorter length of the L-shaped reinforcement,enhancing structural safety.The load-bearing capacity of the new slabs did not significantly decrease and was equivalent or nearly equivalent to that of traditional protruding reinforcement composite slabs,satisfying the requirements for normal service limit state and ultimate limit state conditions.This preliminary validation confirms the feasibility of the L-shaped rabbet design for composite slabs without protruding reinforcement at the ends.关键词
不出筋叠合板/足尺试验/"L"形槽/力学性能/板梁连接Key words
composite slab without extended bars/full-scale test/L-shaped groove/mechanical performance/beam-slab interface分类
建筑与水利引用本文复制引用
刘威,郭小农,文艺,王兵,周森,徐军,戴靠山.."L"形槽不出筋叠合板承载性能足尺试验研究[J].工程科学与技术,2025,57(6):213-221,9.基金项目
四川省重点研发项目(2023YFS0427) （2023YFS0427）
