Experimental Research On The Fire Performance Of Bolted Connections In Parallel Strand Bamboo

As an ancient architectural form, wood and bamboo structure plays an indispensible role in the modern building structure. As is known to all connection is the key to the design of wood and bamboo structure, also, the bolt joint with steel plates(SWS connection) as one of the most common connection form, has been widely used in modern architecture. However,in consideration of characteristics of spontaneous combustion in wood and bamboo, as well as the poor performance of steel under high temperature, the fire performance of SWS connection design should not be ignored. Recently quite a few preliminary reports about it are carried out. In this paper, a new wood substitute material-parallel strand bamboo(PSB),is studied about the fire resistance of SWS connection,for the purpose of improving the safety and reliability of the bolt connection, which can also provide theoretical basis of fire resistance for the further application of PSB structure as building materials.In this paper,12 groups uniaxial tensile test of SWS connections in PSB was carried out first in order to study its mechanical properties and failure morphology in the ambient temperature,and 24 groups fire resistance experiments based on the scenario of heating standard are followed to study the fire resistance performance of SWS connections,then the finite element analysis of a specimen is studied to compare with test results,and finally put forward the calculation formula of SWS connection in PSB at high temperature. The main works are as follows:(1)Taking bamboo thickness, bolt diameter, end distance, row spacing, the number of bolts and so on as influencing facts, to study the ultimate bearing capacity of SWS connections in the ambient temperature, also the failure pattern and strain distribution where bolts locate. The experimental results showed that the variables bring different degrees of influence to the connections about the bearing capacity and failure form;(2)Through the research about the embedding strength of PSB in various temperature, it's clear that as the temperature grows, the embedding strength decreases and failure pattern can be different,finally a groove about embedding strength and temperature can be fitted for further research;(3)By the fire resistance test about the single bolt SWS connection by SPB, the bamboo thickness, bolt diameter, end distance, the load level and surface fire prevention measures are studied to confirm its impacts to fire resistance time, failure pattern, temperature distribution and regulation of charring rate. Results showed that the variables have different degrees of influence on the fire performance of connections, among them load level is most obvious;(4)Further more, single line-double rows and double lines-double rows of bolt connection about fire endurance test are carried, increase considering bolt spacing effect on the fire resistance of all connections, finally, by the comparison between 3 kinds of connections, the failure mechanism of bolt connection under high temperature and the facters which impact the performance of bolt connections will be put forward, to provide theoretical basis for the design of fire resistance about SWS connection;(5)The formula in Code is used to verify the applicability of the calculation of bearing capacity.the result show that the formula of Johanson fit the SWS connection best.The bearing capacity formula of SWS connection at the high temperature is established,then the test results is used to verify the formula and modify it.The results show that on the premise of clear temperature field,the formula summed up in this chapter works well.