Study On Mechanical Behavior And Reliability Analysis Of The Wall-attached Joints Of The Luffing Jib Tower Crane

With the continuous rise of super high-rise buildings,the luffing jib tower crane plays an indelible role,and its safety and stability are the guarantee for the orderly advance of construction.The wall-attached joints of the tower crane consists of two parts,the embedded part and the attachment wall,and it is the guarantee for the safety of the luffing jib tower crane.As the super high-rise building construction process,the wallattaching joint continuously bears the changing vertical load and horizontal load,so it has strict requirements for mechanical performance of this joint.However,at present,there are two main types researches on wall-attached joints at home and abroad,one is to check the bearing capacity of the frame beam and simplify the wall to the compression column according to the structural design criterion,and the second is to analyze the embedded parts and wall of the attached wall joints through the finite element software.There are some limitations in both aspects.It is necessary to analyze the factors that affect the mechanical performance of the wall-attached joints of the luffing jib tower crane by the finite element software on the basis of the test of the wall-attached joints.This paper studies the mechanical characteristics of the wall-attached joints of the luffing jib tower crane in three aspects,through experimental study and finite element numerical analysis.The first is the study of the mechanical characteristics of the wallattached joints through the experimental study,the second is the study of the main factors affecting mechanical characteristics of the wall-attached joints through numerical analysis,and the third is the reliability analysis of the wall-attached joint.The main contents and conclusions include the following aspects:1)The length of the anchor plate has a great influence on the bearing capacity of the specimen.As the length of anchor plate increases,the ultimate bearing capacity of specimens increases.The final failure mode of the specimen is the final main crack formed by the tensile crack generated by the bending moment,but the shorter anchor plate will produce the bending shear crack in the underside of the embedded parts.After the specimen is damaged,the embedded parts are still in the elastic stage,and have a certain intensity surplus.2)The area of end plate has a certain effect on the bearing capacity of specimens.With the increase of the end plate area,the ultimate bearing capacity of the specimen increases gradually.However,due to the limitation of the ultimate tensile strength of the concrete,the effect of the end plate area is falling to the end when the area of the end plate reaches a certain extent.The failure modes of specimens are the fracture of concrete specimens at the main cracks under bending moment,and specimens both produce bending shear cracks.3)The strength grade of concrete has certain effect on the bearing capacity of specimens.With the increase of concrete strength,the bearing capacity of specimens also increases slightly.Failure modes of specimens are tensile failure of concrete under bending moment.When the C60 concrete specimen is destroyed,the part of the embedded part enters the yield stage.4)The angle of the load has a great influence on the bearing capacity of specimens.The bearing capacity increased from 0 to 22.5 degrees,and then began to decrease.There are certain differences in the failure modes of the specimens.When the angle is 0 degrees and 22.5 degrees,the specimens are crushed by concrete and the rest are concrete subjected to tensile failure.5)The width of the anchor plate has little effect on the bearing capacity of the specimen.The width of anchor plate has no effect on the final failure mode of the specimen,which is the concrete breaking at the main crack under bending moment.6)The length width ratio of anchor plate has a certain effect on the bearing capacity of specimens.Under the premise of ensuring the strength of anchor plate,the larger the ratio of length to width,the higher the bearing capacity of specimen.7)The neural network Monte Carlo method based on the selection of number theory can better solve the implicit functional function problem encountered in the process of reliability solving,and the method also has some applicability to the highly nonlinear problem.