Experiment Study On Shear Behavior Of The High-strength Lightweight Concrete Deep Flexural Members

Deep flexural member is the member whose span-depth ratio is less than5, while deepbeam is the simply supported beam whose span-depth ratio is less than2or the multi-spancontinuous beam whose span-depth ratio is less than2.5. Because the span is closed to theheight, the mechanical characteristics of the beam is significantly different from normalbeams, and there are compression state, bending state and shearing state under the action ofload. The code in China, the corresponding formula has been given for calculating theultimate bearing capacity of reinforced concrete deep beams, while the shear performance ofhigh strength lightweight aggregate concrete deep beams has yet to be further studied. Thefailure mechanism was studied through the test of shear performance of eight high strengthlightweight concrete bending members. This article proposes design methods forhigh-strength lightweight concrete deep flexural members, and these methods have theoreticalsignificance and engineering value for promoting the application of high strength lightweightconcrete.The shear performance of high strength lightweight concrete deep flexural members withdifferent shear span ratio and span height ratio was studied by eight HSLC (High StrengthLightweight Concrete) deep beam test, and the failure mechanism and influence factors werediscussed. The researches show that: firstly, the failure form of High Strength LightweightConcrete deep beams is mainly the diagonal-compression failure and shear-compressionfailure, and it usually occurs diagonal-compression failure when shear span ratio less than1,or shear-compression failure when shear span ratio is greater than1; secondly, the influenceof shear span ratio on the shear destruction of deep beam is significantly higher than thespan-depth ratio.This paper analysis experimental data combining the strut-and-tie model with shearregulation in China concrete structure design code which based on previous shear theorymodel, drawing the design method of strut-and-tie model based on Chinese code which hascertain applicability to the shear property of HSLC deep beam.The research shows that the main factors that influencing crack is the shear span ratio. Combining the lightweight aggregate concrete deep flexural members test data of foreign withrelated crack formula, and using mathematical software for data regression analysis, finallythe propositional formula of HSLC deep beam crack capacity was gotten; based on code, therestrictive conditions was put forward which are suitable for oblique section damage of HSLCdeep beam with small shear span ratio, and that is available for reference in design.