| Traditional prefabricated buildings are mainly assembled by prefabricated components,with relatively low overall assembly rate and more joint.This paper is based on Modular Integrated Construction（Mi C）,a new type of assembly building.The building can be broken down into modules with different functions,which are produced,machined,and fitted out in a prefabricated factory.After assembling different modules,it can be applied to various production and living activities,improve the overall assembly rate,reduce the production of joint,and thus improve the construction efficiency.In Mi C module,the truss reinforced concrete wall formwork is used as the formwork in concrete pouring.However,under the action of trapezoidal side pressure produced during concrete pouring,the wall formwork is prone to such problems as mold expansion and slurry leakage.Therefore,this paper takes truss reinforced concrete wall formwork as the research object.The bearing capacity and bending resistance of the wall formwork were studied and the mechanical properties were tested.The innovation point of this paper is that the thickness of the truss reinforced concrete wall formwork is only 30 mm,and the constraint of the wall formwork is set at the steel bar of the truss.Five different types of wall formwork were designed.The effects of truss height,truss spacing and tie bar spacing on the bearing capacity and bending resistance of wall formwork are studied.At the same time,in order to simulate the trapezoidal side pressure generated during concrete pouring and realize the unique constraint mode of wall formwork,the research group designed a loading device and loading system that met the test requirements.The change of strain and deflection of concrete and truss steel bar under trapezoidal load was investigated by arranging relevant measuring points.Based on load-strain,loaddeflection curves and crack development trend of wall formwork,the experimental phenomena and results of five kinds of wall formwork are described.The mechanical properties of different structure wall forms at the same position under trapezoidal load were compared and analyzed.The ABAQUS software was used to conduct finite element numerical simulation of the wall formwork,and the degree of fitting between the numerical simulation results and the experimental results was analyzed.Parametric analysis was carried out by changing the diameters of belly bar and distributed bar in wall formwork.Through the experiment,the design of relevant test loading device and loading system.It can effectively simulate the lateral pressure on the wall formwork during concrete pouring and realize the special restraint form of the wall formwork.According to the characteristic load values of the five wall forms,the cracking load and ultimate load of QMB-3 are both the largest.The cracks on the front of the wall formwork mainly appear near the steel bars of the truss.The rear cracks mainly appear in the middle of the steel span of the two trusses and extend along the longitudinal direction of the wall formwork.Comparative analysis shows that the decrease of truss height leads to the increase of strain of the ventral rod and the decrease of bearing capacity,which is not conducive to the overall performance of the wall formwork.The bearing capacity and flexural performance of the truss can be improved by reducing the space between trusses and increasing the steel bars.But from the practical and economical point of view,its performance far exceeds the actual requirement,resulting in resource waste.Adjusting the distance between pull rods has a positive effect on improving the bearing capacity and bending resistance of wall formwork.However,if the distance between pull rods is too small,it will lead to uneven local force of wall formwork and transverse cracks.In this paper,it is considered that the steel bar height of the wall formwork is 140 mm,the steel bar spacing of the truss is 600 mm,and the tie bars are evenly arranged with a spacing of 800 mm,which shows superior mechanical performance.Figure [110] Table [19] Reference [61]... |
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