Study On Basic Mechanical Properties Of New Type Of Precast Lightweight Steel And Lightweight Aggregate Concrete Shear Wall

According to Xinjiang's regional characteristics of high seismic frequency,cold climate and rich desert sand resources,as well as the shortage of construction technology and dispersed layout of villages and towns,this paper proposes a new type of precast lightweight steel and lightweight aggregate concrete composite shear wall structure(PLSCW),which is suitable for one or two floors of rural buildings.This structure is mainly composed of two different types of wall limbs named general wall limb and key wall limb,keeping the advantages of low transportation difficulty,convenient installation,excellent seismic capacity and good thermal insulation property.In this paper,the mix proportion of desert sand lightweight aggregate concrete in PLSCW wall material and the mechanical properties of PLSCW wall were mainly studied.The main research works and conclusions are as follows:(1)Through the orthogonal test of 16 groups of 96 cube test blocks of desert sand lightweight aggregate concrete,the influences of water-binder ratio,sand ratio and desert sand substitution ratio on the performance of concrete were analyzed,and the reasonable mix proportions of LC20 grade and LC25 grade were obtained.Furthermore,the physical and mechanical properties of these two strength grades of desert sand lightweight aggregate concrete were studied experimentally.The results indicate that it is feasible to use desert sand to replace some fine aggregates in lightweight aggregate concrete for the production of lightweight energy-saving wallboard;the lightweight aggregate concrete mixed with desert sand has the characteristics of light bulk density,low thermal conductivity,slump and main mechanical properties meeting the requirements of national norms.(2)Through the axial compression test of four PLSCW wall limb specimens,the mechanical properties of PLSCW wall limbs under vertical load were studied.The results indicate that under the vertical load,the failure mode of PLSCW wall limb is the crushing of concrete at the top and the buckling of longitudinal steel wire.The PLSCW general wall limb specimens have small axial stiffness and low axial bearing capacity,while the PLSCW key wall limb specimens with two thin-walled steel boxes pre-buried are significantly larger than the general wall limbs.The axial compression bearing capacity can be calculated according to the current code for design of concrete structures.(3)Through the pseudo-static test of five PLSCW wall limb specimens and one ordinary reinforced concrete shear wall specimen,the mechanical properties of PLSCW wall limbs under constant vertical load and cyclic lateral load were studied.The results show that,the failure mode of PLSW wall limb with high shear span ratio is compression-bending failure,while the limb with low shear span ratio is bending-shear failure.The cracking load,peak load and ultimate load of PLSCW general wall limb specimens are slightly higher than those of ordinary reinforced shear wall specimens,but the deformation capacity and energy dissipation capacity are decreased,while the PLSCW key wall limb specimens not only have significantly higher bearing capacity,but also have better deformation capacity and energy dissipation capacity.The ultimate displacement angle of PLSCW wall limb is between 1/50 and 1/75,which meets the elastoplastic deformation capacity requirements of shear wall structure under the action of large earthquake and has a certain safety reserve.The flexural capacity of PLSCW wall limbs can be calculated according to the formula for calculating the flexural capacity of normal section proposed in this paper,and the calculated values are basically consistent with the experimental values.(4)Compared with the key wall limbs of pre-buried thin-walled steel at both ends,the general wall limbs are only equipped with steel mesh,and the mechanical properties under vertical loads and horizontal loads are infer to the former.The general wall limbs should be used to these general parts of between windows and under windows as the first line of defense for the structure,and the key wall limbs should be applied to the key part of the joint of the vertical and horizontal walls as the second line of defense of the structure.