Research On The Mechanical Properties Of GFRP Connectors Under The Age Of Concrete

Prefabricated construction,under the progress of the 14 th Five-year Plan,has become an important trend in the development of construction technology in the future.At present,precast concrete sandwich insulation wall panels are more and more widely used in prefabricated constructions.Collectors are the most important components to connect the concrete slabs on both sides of the wall panels,and their mechanical properties are very important to the safety of the sandwich wall panels.The new connector made of FRP material has good mechanical properties,and its poor thermal conductivity can effectively reduce the cold and hot bridge effect in the wall panels.In the practical engineering,first of all,after the production is completed in the factory,the precast concrete sandwich insulation wall panels need to accept steam curing and rest for 3-5days,and then they will be transported to the construction site for hoisting.The concrete strength at this time is approximately equivalent to the concrete strength cured for 14 days under standard conditions.Under-aged concrete curing has an impact on the mechanical properties of GFRP connectors in wall panels,which is an engineering safety issue that cannot be ignored.In this paper,the tension capacity and shear capacity of GFRP connectors in sandwich insulation wall panels with a concrete curing age of 14 days are tested,and ABAQUS is used conduct modeling analysis on the test to draw the following conclusions:1)GFRP connectors have good tensile properties,and the average maximum strain during tension is 0.2916%.The test ended with wedge-shaped breakage of the concrete and the connectors being pulled out of the concrete,and the results show that the average tensile bearing capacity is 17.9k N.2)In the shear capacity test,the breakage form of most connectors is fiber breakage,the connectors are sheared,a few of the connectors fail to anchor,and the connectors are cracked and pulled out of the concrete at the same time.The average ultimate shear capacity of a single connector in the test is 7.39 k N.3)The capacity level of the connectors in the prefabricated sandwich insulation wall panels with a 14-day curing period is calculated according to the stand requirements,and the results show that this connector meets the practical engineering safety requirements and has a large safety reserve.4)The finite element analysis software ABAQUS is used for the modeling analysis of tensile test pieces and shear test pieces.The capacity characteristics and breakage forms of the pieces under tensile and shear forces are studied separately.The simulation results are basically consistent with the test data,so the same modeling method can be used to perform parametric analysis on the mechanical properties of the connectors.5)The parametric analysis of the tensile properties of the connectors shows that for7 days,14 days,and 28 days of concrete curing,the tensile capacities of the pieces are16.1k N,18.5k N,and 24.9k N,respectively,increasing by 14.9% and 34.6% respectively.The thickness of the insulation layer has a significant impact on the tensile performance of the pieces,the tensile capacity of the 40 mm insulation layer is 7.39% less than that of the 30 mm insulation layer,and the 50 mm insulation layer is 7.8% less than that of the40 mm insulation layer.The embedding depth of the connector has a significant impact on the tensile performance of the test pieces: the deeper the embedding depth,the greater the tensile capacity.6)The parametric analysis of the shear performance of the connectors shows that a)the concrete strength grade has little effect on the shear performance of the pieces;b)the thickness of insulation layer has a significant effect on the shear performance of the pieces:the ultimate shear capacity of the pieces with the 40 mm insulation layer is 50.43% higher than that of the 50 mm insulation layer,and the 30 mm insulation layer is 29.48% higher than that of the 40 mm insulation layer;c)for wall panels with the same dimensions,the transverse spacing and longitudinal spacing of connectors have a significant impact on the overall shear capacity of the pieces: the smaller the spacing,the greater the shear capacity of the pieces.Figure [57] table[8] reference [60]...