Study On Mechanical Properties Of Precast Light Concrete Wallboard Under Vertical Load

The constraint wallboard structure system is a new kind of building structure system,Wall is made by multiple pieces of precast light concrete wallboard through panel side swallow tailed grooves adhesion with vertical seam mortar, it is constrainted by surrounding prefabricated concrete constructional column and cast-in-situ ring beam,that is the formation of constraint wallboard structure.This structural system is suitable for low-rise buildings such as the new rural construction, urban relocation building, etc., according with the basic requirements of "green building", conduciving to achieve the goal of building energy conservation and emissions reduction. Precast light concrete wallboard use formwork extrusion process, having low production cost and high efficiency, its main materials are cement, ceramsite, slag,fly ash and construction waste, etc.,can achieve circular economy.Precast light concrete wallboard is served as bearing members, possessing the double function of load-bearing and maintenance. So we need to study mechanical performance of precast light concrete wallboard under the vertical load.This article through experiment and numerical simulation methods,we have a systematic research on mechanical properties of wallboard under vertical axis load and eccentric load, such as failure process, failure pattern, ultimate bearing capacity,etc.,it will provide a scientific basis for the design and construction of constraint wallboard structure system.The research work and main results are as follows:(1)The basic physical and mechanical performance index of the precast light concrete wallboard through experiment to measure, providing the method of choosing standard compressive test block refer to the relevant specification.The compressive strength of wallboard standard block is 6Mpa, elastic modulus is 4300 Mpa, about 20% of the same strength grade of concrete, poisson’s ratio is 0.17.Based on the hole block uniaxial compression test, fitting the stress-strain curve of the wallboard material, combining with the concrete stress-strain curve equation,we can deduce uniaxial compression constitutive equation of wallboard material.(2)four groups wallboards of different heigh thickness ratio for compression test under the vertical axis uniformly distributed load, study the wallboard mechanical properties such as failure process, failure pattern, ultimate bearing capacity,etc.under uniformly distributed load. The first crack of Wallboard appeared in the edge, the value generally for the limit loading of 85% ~ 90%,along with the increasing of high thickness ratio, lateral deflection of wallboard increasing. when the specimen high thickness ratio is less than 14, its failure pattern is mainly compressive fracturing, when high thickness ratio is greater than 17.5, its failure pattern is out-of-plane instability destruction,along with the increasing of high thickness ratio, ultimate bearing capacity of wallboard declining.(3)Grouted wallboard and not grouted wallboard proceed to compression test under eccentric linear load,partical grouted wallboard for compression test under eccentric concentrated load, to study the effect of grout hole to wallboard bearing capacity. Tests showed that: all hole grouted wallboard has obviously improving in bearing capacity, the bearing capacity of grouted wallboard for 1.7 times of not grouted wallboard; the bearing capacity of local grouted wallboard does not appear obvious enhancement, wallboard local grouted have little impact on bearing capacity, so suguest that groute wallboard all hole in order to improve it’s local bearing capacity.(4)compression test of wallboard under eccentric linear load, wallboard appear local compression failure under eccentric linear load,the wallboard damage mainly in edge of wallboard,the cracking load and failure load of the specimen are also low and not appearred out-of-plane instability destruction; wallboard appear local compression failure under eccentric concentrated load, when the eccentricity smaller, the failure mode of the specimen showed splitting failure, when the eccentricity larger, the failure mode appear extrusion broken at wallboard contact with block.(5)wallboard standard compressive strength and material compressive strength is researched by using ABAQUS software. Material compressive strength is about 1.94 times the wallboard standard compressive strength by using the first strength theory; Model for calculating of wallboard under vertical load is established by using buckling analysis method, Nonlinear buckling analysis arc method(riks algorithm) to simulate wallboard plane instability situation, numerical analysis concluded that the axial displacement, midspan deflection are in good agreement with test results, The error of ultimate bearing capacity within 5%, the results show that numerical simulation model can better simulate the actual stress distribution of wallboard(6)On the basis of experimental results and numerical simulation analysis, wallboard formula of vertical bearing capacity under axis uniformly distributed load is established,deduced the relationship between axial compressive influence coefficient and wall thickness ratio. According to the experimental research results, giving local compressive bearing capacity formula under concentrated load.The wallboard structure measures are put forward, which will provide a scientific basis for engineering design and construction.