Study On Mechanical Properties Of FRP-concrete Connectors At Early Age

Prefabricated sandwich insulation thermal insulation composite wallboard has advantages of high efficiency and good oneness and durability,has been widely used in exterior wall retaining structure at home and abroad,insulation sandwich wallboard of FRP fittings as an important embedded parts inside the wall,is a sandwich insulation wall bearing capacity size and thermal performance of the key.This paper is one of the research contents of Anhui Natural Science Foundation 1908085ME173.In the actual project,prefabricated components factory generally after the completion of concrete pouring on the core insulation composite wall plate steam maintenance 6h,static 3 days is shipped to the site for installation,at this time the strength of concrete is roughly equivalent to the standard maintenance of 14 days when the strength.Few domestic scholars have studied whether FRP connectors are still safe enough under the condition that the curing age of concrete is not full.Therefore,based on the above engineering background,this paper studies the anti-pull and shear mechanical properties of FRP connections in reinforced concrete composite wall slabs under the condition that the concrete age is not satisfied.This paper adopts theoretical analysis,performance test,simulation,parameter analysis and other research methods,selecting MS30FRP fittings for tensile and shear test,the test results on the basis of analyzing the failure form,failure process,the strain curve and the load displacement curve,and fitting to the data measured in experiment safety evaluation,numerical analysis and the finite element parametric analysis.The following conclusions are mainly drawn:（1）Three sets of concrete anti-pull test block damage form is basically the same,are the anchoring side of the connection scraping damage,the surface of the connecting parts only slight wear.The depth of concrete damage in the anti-pull test is about 2cm,and the damage area is about 30cm²-50cm².In the anti-pull test,the maximum pull force that the concrete test block can withstand is 20.79k N,the corresponding displacement is 7.945mm,the peak strain in the middle of the connection is about 5527.99×10^-6,and the end peak strain is about 4418.83×10^-6.（2）In the anti-shear test of prefabricated sandwich core insulation reinforced concrete composite wall slabs,there are 3 forms of wall damage:the cracking damage of the fiber layer of the connecting parts,the breaking of the fibers at the anchoring point of the connecting parts,and the destruction of the concrete at the anchoring points resulting in the failure of anchoring,of which the damage of the connecting parts themselves is mainly.Anti-shear test measured the normal use of wall plate limit load and carrying capacity limit load is 50.03k N,100.45k N.The safety evaluation results of the connecting parts prove that the carrying capacity of the wall plate and the deformation size of the connecting parts are in accordance with the specification and the safety is high under the condition of 14 days of concrete maintenance.（3）In the numerical analysis results,the load displacement curve of the connecting part anti-pull and shear is close to the test results,and the error is small,which indicates that the established model and the selected parameters are reasonable,which is more consistent with the actual situation,and the corresponding parameter analysis can be carried out.（4）When the curing age of concrete is 14 days,the anti-pull parametric research shows that:the concrete strength has a greater i MPact on the pull-resistant carrying capacity of the connecting part,the higher the concrete strength,the greater the anti-pull carrying capacity of the FRP connection,the higher the anchoring depth of the connecting part is increased by 34.21%,and the anti-pull carrying capacity of the test block is increased by 40.21%accordingly 87%,anchoring depth on the connection anti-pull carrying capacity is more obvious,S3 connection anti-pull limit carrying capacity is the highest,co MPared with the test MS30 connection increased by 65%,S1,S2,S4connection tensile limit carrying capacity is closer,The average is 26%higher than the MS30 connector,so the S3-threaded FRP connector is recommended.（5）When the curing age of concrete is 14 days,the anti-shear parameterization study shows that:the concrete strength grade has less impact on the carrying capacity of the composite wall plate and can be ignored,the spacing between the connecting parts has a greater effect on the bearing capacity of the wall board,the larger the horizontal or vertical arrangement spacing of the FRP connector,the greater the normal use of the limit load on the wall plate Small,horizontal spacing（portrait spacing）increased from 400mm to500mm,the maximum reduction of the limit load,the anchor depth of the connecting part increased by 34.21%,the anti-shear carrying capacity of the wall plate correspondingly increased by 29.21%,The anchoring depth has a great influence on the shear carrying capacity of the connecting part,but it is significantly weaker than the i MPact of the anchoring depth against the pull carrying capacity.Finally,the mechanical properties of FRP connections used in the experiment are summarized,the factors that may affect the carrying capacity of composite wall plates are analyzed,and suggestions are given,and the next research contents of prefabricated sandwich core insulation wall plates and FRP connections are pointed out.Figure[75]table[17]reference[73]...