Study On Serviceability Of High Strength Lightweight Aggregate Concrete Deep Flexural Members

High-strength lightweight aggregate concrete(HSLWC)with light weight,high strength,good fire resistance and heat preservation is a kind of green building materials with good application prospect.It can reduce the size of members,provide more open space,and reduce self-weight of structure after the application of HSLWC to deep flexural members,while it leads to easy shear failure without obvious sign due to higher brittleness.Meanwhile,the serviceability performance of deep flexural members exposed to public view or environmental elements is quantified by the width of diagonal cracks,and the wide diagonal cracks will damage the durability and the applicability of structure.However,there is less researches on serviceability of HSLWC deep flexural members.Therefore,it's necessary to carry out the research on serviceability.Based on the experimental investigation on 15 HSLWC deep flexural members,combined with relevant researches on serviceability of NWC deep flexural members,the serviceability of HSLWC deep flexural members has been analyzed.The main contents are:1.According to the experimental investigation on shear performance of 15 HSLWC deep flexural members,the process of service of specimens was studied accompanied by the generation and extension of diagonal cracks.Then,the effects of shear span-depth ratios,the height of section and width of loading plates on diagonal cracking strength and width of diagonal crack were researched.Results show that there is no size effect for diagonal cracking strength,while there is obvious decrease of diagonal cracking strength with the increase of shear span-depth ratios.2.A large database of 174 experimental results of deep flexural members diagonal cracking load was assembled through an extensive review of the literature.Then the influence factors were analyzed,and a conservative model to predict diagonal cracking load was proposed.A database of 53 test results of diagonal crack width was collected.Then the fact that web reinforcement is the primary variable that affects the maximum width of diagonal cracks was confirmed,and then a table was created that correlated the the width of diagonal cracks to the corresponding percent of the ultimate capacity.3.Whether the diagonal cracking load calculation model and table for predicting the level of residual shear capacity in diagonally-cracked deep flexural members could be applied to HSLWC deep flexural members was discussed.The results show that the proposed model can predict the diagonal cracking load of HSLWC deep flexural members and has safety bargain.The proposed chart can be used to predict residual shear capacity in diagonally-cracked HSLWC deep flexural members when there is not a high level of accuracy demand.4.Whether the width of diagonal crack of deep flexural members under service load could meet the requirements for crack width in Chinese and American codes was discussed.It shows that the width of NWC deep flexural members designed using GB 50010-2010 can satisfy the width limit under service load in codes.While it suggests that enhacing the web reinforcement is good to control crack width under service load when GB 50010-2010 used for HSLWC deep flexural members.The research on serviceability of HSLWC deep flexural members has great significances in analyzing the durability,research on service performance in full life of members,guiding engineering practice and promoting the wide application in domestic engineering.