Papers by Keyword: Slip Coefficient

Abstract: Fire safety is a major concern with steel structures. Actually, steel structures were not fatally destroyed in most cases of fire. These damaged steel structures may be reused after structural inspection, safety appraisal and necessary repair. Bolted connections are the most widely used connection in steel structures. Slip coefficient is a key parameter to calculate the slip bearing capacity of bolted slip-critical connections. Currently there are few research results available about slip coefficient of bolted slip-critical connections after fire. To obtain the effect of heating and cooling on slip coefficient, a series of slip load tests on connections that had been heated and cooled to ambient temperature were carried out in this study. Methods of friction surface treatment included shot blast and painting inorganic zincs after shot blast. Test results show that heating and cooling have a great effect on slip coefficient of connections with two methods of friction surface treatment, among which effect on connections with shot blasting surfaces is more significant.

Abstract: Aimed at the wall slip phenomenon of micro flow, the wall slip boundary condition was added to simulate the process of the micro flow by Polyflow based on the traditional flow analysis method. The effect of the wall slip on the micro flow was verified by comparing the pressure difference data obtained from the simulation with the quoted test data. In addition, based on the Generalized Navier’s slip law, the shear stress and slip coefficient were researched by the numerical simulation analyses to find out the influence of the key factors on the phenomenon of wall slip. The results show that the phenomenon of wall slip is an important factor that cannot be ignored in the micro flow. And only under the high shear stress, the wall slip phenomenon will have an obvious influence on the micro flow. Along with the decrease of the slip coefficient, the wall slip phenomenon becomes more apparent and the micro flow tends to be stable.

Abstract: The use of steel plates has been greatly increased in bridge construction, particularly for long-span bridges, and connections between the plates are made usually using high-tension bolts. However, the specifications on the use of large-sized high-tension bolts are not adequately stated in the currently available construction manuals. In order to provide further information on the use of the large-sized high-tension bolts, this study experimentally investigated the relaxation and slip behavior of M30 bolts with varying bolt size and plate thickness. In addition, numerical evaluation using FEM was performed to investigate the compressive stress occurred on the inside of bolt hole. The analyzed results were compared with the stress distribution measured from strain gages attached on the bolts and bolt holes. From the study presented herein, it was found that the relaxation was increased as the size of bolt increased, and that the M30 high-tension bolts developed slip coefficient greater than 0.4. The thickness of plate did not significantly affect the compressive stress distribution around the bolt holes.