Research On Structural Design Method And Assembly Joints For Reproduction Exhibition Of Large Scale Cultural Relics

Yungang Grottoes are huge in scale,and they are one of the four great treasure houses of grotto art in China and play an important role in the history of art in China and the world.Because the cultural relics of caves and temples belong to immovable cultural relics,it has been the wish of Yungang people for many years to copy the Yungang Grottoes and publicize and promote the Yungang Grottoes culture to the people all over the world.Cave No.18 in Yungang Grottoes is a grotto with large scale,complex technology and high artistic value.It is of great significance to replicate Cave No.18 with the concept of assembled steel structures,to practice the important instructions of the General Secretary,and to make the heritage alive,so as to carry forward the traditional culture of the Chinese nation.In view of the needs of the overall copy of the scale Cave No.18 in Yungang Grottoes and the demand of outdoor display,the corresponding assembly steel structure system and design method were put forward and the related new assembly connection joints were studied.This paper is mainly divided into three chapters,which are the research of high-strength through-bolted beam-column end-plate connections,research of flexural behavior of square steel tubular beam with bolted connection and design and implementation of modular assembly system for steel frame assembly in Grottoes.The results are summarized as follows:(1)Single-direction static loading tests of 4 beam-column joints with high-strength through-bolted end-plate connections were carried out to investigate their mechanical properties during the trial production of the main Buddhist head of Cave No.18 in Yungang Grottoes.The influences of joint formation,bolt wrench type and column strengthening in the joint panel zone on the bearing capacity of end-plate connections,bending performance,joint stiffness and deformation characteristics have been analyzed.The test results indicated that when the thickness of square steel tubular beam-column was thin,the initial stiffness,bending capacity and deformation resistance of the joint panel zone under compression could be improved by using nested inner core to strengthen the joint panel zone,while ensuring the nesting tightness between the inner core tube and the column and the pre-tightening of high-strength bolts.And the finite element software ABAQUS was used to simulate the high-strength through-bolted beam-column end-plate connections,and the results of finite element simulation were in good agreement with the experimental results,providing a reference for improving the joint design.(2)Because a square steel tube has the advantage of large section modulus and no weak axis,it was widely used in overall copy of the scale Cave No.18 in Yungang Grottoes.According to the original structural design scheme duplicated in the Cave No.18 in Yungang Grottoes,the modular attached frame and the integral main steel frame were joined by square steel tubes welded in advance and assembled by transverse bolts.In this thesis,a new type of assembled bolted connection between two square steel tubes was proposed to meet the needs of splicing joint between square steel tubes,and the connection section did not protrude the main section of the square steel tubular beam.In order to understand the flexural behaviorof the bolted square steel tube beam,a single specimen was tested,and the relationship between load and midspan deflection and the relationship between load and strain at the key points were analyzed.The test results showed that the relationship between load and mid-span deflection of bolted square steel tube beams was basically linear,and the section of beams and connectors conformed to the assumption of plane section.And the finite element simulation analysis of the bolted square steel tube beam was carried out,which was basically in agreement with the test results.(3)Relying on the practice foundation of the early eastern equal proportion reproduction Buddha of Cave No.18 in Yungang Grottoes and Flank equal proportion reproduction Buddha of Cave No.18 in Yungang Grottoes,the technical process research and the overall replication scheme design and implementation of the structural part of the overall replication project of Cave 18 of Yungang Grottoes were carried out.Considering the actual situation of the project,the design and implementation scheme of the steel frame assembly system for modular replication of the grottoes were finally determined,and the overall replication of the same scale as Cave No.18 in Yungang Grottoes was successfully completed.For the structural part,standardized components,adjustable assembly and finite element simulation analysis were three key technological innovations in the process of high fidelity reproduction of Cave No.18 in Yungang Grottoes.