Study Of The Effect On The Dynamic Characteristics Of Steel Frame By The Nodes Of Bolts Connection

Steel structure are widely used in large public buildings, high-rise structure and industrial buildings with it’s light quality, short cycle of production, cheap costs. The rapid increase of the population accelerate the process of the urbanization in our country, in order to accommodate more population on the limited land resources, the urban construction is to be a higher direction of development, but the traditional reinforced concrete structure is difficult to meet the demand of the structure of the high-rise building. First of all, the stability of the steel structure is better, it can withstand greater external loads and keep it’s own structure security and the overall performance;Second, the technology on steel structure construction is relatively simple, general engineering only need a simple training for workers to work;Once again, the construction of steel structure buildings has high efficiency, it can complete the installation with a short period of time; At the same time, the steel structure also has good advantages on the seismic performance, especially for some frequent earthquake area, the seismic performance is particularly important. The steel structure framework as the main composition system of high-rise building structure has good ductility, simple construction and effectively resisting the seismic load, etc. There generally are three kinds of connection mode in the steel structure framework:welding connection, rivet connection and bolted connection, bolted connection can be divided into high strength bolted connection and ordinary bolted connection. High strength bolt connection is mainly on tighten bolt rod inside the pretension to connect multiple components, it will produce strong relative to the friction between connected component. Because of the high strength bolts with this tight tension, the connected component of the stiffness and integrity are much better than the components of the ordinary bolt connection. In this paper, studying the comparative about the ordinary bolts and the high strength bolts for steel structure frame mode.Modal is the inherent structure features, the steel frame adopts different bolt connection is to have different modal, each order modal has certain frequencies, mode shapes and damping. Modal analysis is the linear time-invariant system vibration differential equations of physical coordinate transformation for the modal coordinates, and then make the equations decoupled with modal parameters which is described as a set of independent equation, finally find out the corresponding modal parameters. The coordinate transformation matrix is the modal matrix, and each column is the modal vibration mode. Modal analysis can help us evaluate the existing structural system, can also identify damage of structures and put forward corresponding measures on reinforcement.This paper is on the premise of experimental comparison, do the simulation analysis of the difference of modal on the steel frame in two kinds of bolt connection which is ordinary bolts and high strength bolts by the large general finite element software ANSYS, and do the comparative analysis of the modal test and finite element simulation difference and analyzes its reason. The main contents on the research in this paper are:it describes the research status and development trend of high strength bolt、 modal analysis, does the analysis of the basic theory of modal analysis, introduces several common methods of modal analysis, it can do the analysis of structural dynamic characteristics of high strength bolt and common bolt better based on the vibration characteristics of modal parameters;do a detailed introduction on the method of the vibration modal parameter identification, it describes the specific methods and steps of the steel frame structure modal test in detail, including the design of steel frame structure, the introduction on the test device(the test system, the way of incentives, the arrangement of the acceleration sensor, the selection of measuring point, etc.), and do the descriptions of the test on steel frame model, do the collection of the test data and get the corresponding conclusions by the comparative analysis;On the basis of the modal test on the steel frame, using the AN SYS to do the comparison and analysis of test results, doing the analysis on the cause of the difference of the modal parameters calculated by the simulation test;summarizing and looking forward to the research work, putting forward some relevant suggestions on improving and practicing the research.