Study On Mechanical Properties Of Fully Prefabricated Slabs Connected With Concealed-beam

Prefabricated concrete structure has the advantages of fast construction speed,energy saving and environmental protection,and less labor demand.It is the development direction of China's construction industry.At present,the application of prefabricated slabs is mainly based on laminated slabs with different connection methods.The wet work volume is large and the construction quality should not be guaranteed.To this end,the research group proposed a connection method of all-prefabricated slabs with concealed-beam.Concealed-beam prefabricated slab connection is a new connection method based on fully prefabricated slab.The connection method has continuous force transmission and good integrity at the connection,which reduces a lot of wet operations.It also has the advantages of convenient construction,energy saving and environmental protection while ensuring the bearing capacity,and has a high application prospect.Based on the ABAQUS finite element software,a model of the existing test cast-in-place plate was established to simulate its failure form and stress process under static load.The simulation results were compared with the existing tests.The results showed that the error was within the allowable range.Furthermore,the reliability of the simulation method will be explained.Using the above simulation method,a model of fully prefabricated slab-to-slab connection of concealed-beam and a fully prefabricated beam-to-slab connection of concealed-beam was established and simulated to analyze the mechanical properties of concealed-beam.The engineering feasibility of fully prefabricated slab-to-slab connected with concealed-beam was discussed by comparing the bending performance of the slab connected with concealed-beam,cast-in-place slab and laminated slab and the analysis of the shear capacity of slab connected with concealed-beam.The results show that the concealed-beam connection method has a better force transmission mechanism,and the longitudinal steel bars overlap each other to ensure the continuity of the longitudinal force transmission of the reinforced steel bars.The shear steel bar meets the requirements of the shear bearing capacity of the joint.Thus it's feasible in civil engineering.The influence of different factors on the bending performance of the full prefabricated slab-to-slab connected with concealed-beam is analyzed.The results show that increasing the length of the shear bar can increase the yield load and ultimate load of the slab connected with concealed-beam.The larger the length of the shear steel bar,the worse the coordinated deformation of the steel bar and the entire splicing slab is;the connection length has less effect on the bending performanceof the slab connected with concealed-beam;the strength of the concrete at the connection and the friction coefficient of the old and new concrete have almost no effect on the bending performanceof the slab connected with concealed-beam.The engineering feasibility of fully prefabricated beam-to-slab connected with concealed-beam was discussed by comparing the failure process and the bearing capacity at each stage of the concealed-beam beam-to-slab joint and cast-in-place beam-to-slab joint.The results show that the force transmission mechanism of the concealed-beam connection is better,and the joint are subject to joint forces.The bearing capacity of the concealed-beam beam-to-slab joint is slightly lower than that of the cast-in-place beam-to-slab joint.The failure process is similar and the deflection development curve is full.The overall performance of the concealed-beam beam-to-slab joint can be equivalent to the cast-in-place beam-to-slab joint.The influence of different factors on the bending performance of the full prefabricated beam-to-slab connected concealed-beam is analyzed.The results show that: the overlap length has little effect on the bending performance;the strength of the joint and the friction coefficient of the old and new concrete have almost no effect on its bending performance.According to the simulation results,it can be obtained that the performance of the concealed-beam connection method can be equivalent to cast-in-place,so the concealed-beam prefabricated slab bearing can be designed according to the calculation formula of the cast-in-place slab;The values of the parameters at the joints in the preliminary design are given.