Experimental Research On Fire Performance Of Glulam Structure Members

Glulam structure is widely used in residential buildings and public buildings in the United States,Canada,Sweden and New Zealand.In recent years,glulam structure has also gained more and more attention and application in China.However,the glued wood has flammability and the domestic research on fire resistance of glulam structure is not enough,which limits the application of glulam structure.In view of the case,the charring rate,mechanical properties after fire and fire resistance of the glulam beam and glulam column which are the main load-bearing members of glulam structure,were tested and the corresponding theoretical analysis with finite element simulation were carried out in this dissertation.The main content is listed below:(1)The wood properties of domestic Pinus sylvestris and the foreign imported Douglas fir under ambient temperature were tested,in order to supply wood material database and provide material parameters for the finite element simulation.(2)The charring rate test of 14 glulam beams exposed to three-side fire and 12 glulam columns exposed to four-side fire was carried out.And the temperature filed was simulated by ABAQUS to calculate the charring rate.It shows that the adhesive can maintain good adhesive performance under fire;the charring rate is related to the time exposed to fire,the surface treatment(brushing retardant coating or not).(3)The mechanical properties of glulam members which were from charring rate test exposed to different fire time were tested,and compared to those without fire,to learn the residual bearing capacity and damage form of glulam member after fire.It shows that the residual bearing capacity and stiffness of exposed specimens decrease obviously with increasing fire time,the decline degress decreases with the increase of the section size.(4)Based on the theory of residual cross section,the residual bearing capacity was calculated.Through the secondary development of the finite element software ABAQUS,the constitutive model which can reflect the anisotropy of wood and different bebavor of tension and pressure was compiled.With the constitutive model,the numerical simulation of the residual bearing capacity was carried out.The theoretical results and finite element results agree with the test results.(5)To learn about the effective factors of fire endurance,such as cross-section,load level,fire retardant coating,the fire endurance test of 18 glulam beams exposed to three-side fire and 10 glulam columns exposed to four-side fire,including the contrasting specimens,was carried out.The research shows that the fire endurance is significantly reduced with the increase of loading level,the fire endurance increases with the increase of section size,and retardant coating can improve fire endurance to some degree.(6)The calculated fire endurance of glulam members,which is based on the theory of residual cross section,agrees well with the test results.By using the constitutive model,ABAQUS calculates the coupled thermal-mechanical analysis.The simulated failure mode agrees well with the test results,and compared to the test results,the simulated displacement-time curve has consistent trend,but the fire endurance has a certain error.According to the finite element simulation,the fire endurance change rule under different load ratio levels and different cross-section size was obtained.