When a fire occurs in an underground shield tunnel,it can result in substantial property damage and cause permanent harm to the tunnel lining structure.This is especially true for large-diameter shield tunnels that ha...When a fire occurs in an underground shield tunnel,it can result in substantial property damage and cause permanent harm to the tunnel lining structure.This is especially true for large-diameter shield tunnels that have numerous segments and joints,and are exposed to specific fire conditions in certain areas.This paper constructs a full-scale shield tunnel fire test platform and conducts a non-uniform fire test using the lining system of a three-ring large-diameter shield tunnel with an inner diameter of 10.5 m.Based on the tests,the tem-perature field distribution,high-temperature bursting,cracking phenomena,and deformation under fire conditions are observed.Fur-thermore,the post-fire damage forms of tunnel lining structures are obtained through the post-fire ultimate loading test,and the corresponding mechanism is explained.The test results illustrate that the radial and circumferential distribution of internal temperature within the tunnel lining,as well as the radial temperature gradient distribution on the inner surface of the lining,have non-uniform dis-tribution characteristics.As a result,the macroscopic phenomena of lining concrete bursting and crack development during the fire test mainly occur near the fire source,where the temperature rise gradient is the highest.In addition,the lining structure has a deformation characteristic of local outward expansion and cannot recover after the fire load is removed.The ultimate form of damage after the fire is dominated by crush damage from the inside out of the lining joints in the fire-exposed area.The above results serve as a foundation for future tunnel fire safety design and evaluation.展开更多
Glue-laminated timber(GLT)is an engineered wood product widely used in mass timber construction for its strong structural and fire-resistant properties.However,the fire performance of GLT varies significantly due to t...Glue-laminated timber(GLT)is an engineered wood product widely used in mass timber construction for its strong structural and fire-resistant properties.However,the fire performance of GLT varies significantly due to the natural and uncertain phenomena(moisture,exposure time,isotropic,homogenous properties,etc.)of fire and timber.This makes it difficult to predict the fire behaviour of the GLT structural elements.To ensure building safety,it is crucial to assess GLT’s fire behaviour and post-fire structural integrity during the design stages.This study conducted the experimental tests of GLT beams(280 mm×560 mm)without loading(1.4 m)and under a four-point bending load(5.4 m).Tests identified thermal behaviour and charring rates of GLT beam.Then,the residual stiffness of the GLT beam was calculated,and the charring rates of the beams were compared with Australian and European standards.Reliability analysis was conducted for beams for a fire exposure of 120 min,considering the charring rates observed through the analysis and simulating the fire insulations.Results show that the charring rate of GLT made with spruce pine timber varied between 0.43 and 0.81 mm/min,with a mean rate of 0.7 mm/min,aligning with both Australian and European standards.However,considering timber density and moisture content,the charring rates in Australian standards were conservative.The study also found that structural capacity significantly degrades under fire,with a 22%reduction in flexural stiffness after 120 min of exposure.Additionally,GLT beams can safely function for 30 min under 75%of their design moment capacity and for 60 min under 50%capacity.展开更多
Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited,it propagates fire and accelerates the enclosure fire ...Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited,it propagates fire and accelerates the enclosure fire growth. Two types of lining materials were studied during the tests:block board and plywood. The test was conducted in an ISO 9705 room,where linings were mounted on walls without the ceiling. By changing the heat output of the burner,the ventilation,etc.,the concentrations of CO2/CO of different lining materials were researched. The effect of test conditions on the production of CO2/CO of different lining materials was investigated,and useful experimental data were provided for the further development of numerical modeling to simulate enclosure fire growth lined with combusti-ble materials.展开更多
To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load tes...To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load test and the other two for the one-side fire tests.Besides,temperature probe points were set on the sandwich walls to obtain the temperature distribution.Meanwhile,the model of the sandwich wall was established in the finite element software by the method of core material stiffness equivalent.The temperature distribution and performance reduction of materials were also considered.The residual bearing capacity of specimens after fire exposure were simulated considering the effects of web spacing,wall panel thickness and fire exposure time.Because the sandwich wall panels were stressed by eccentric compression after a fire,the residual compressive strength of the wall panel after the fire can be calculated through the eccentric loading analysis.Compared with the numerical results,it can be concluded that the effectiveness of calculation method of residual bearing capacity after fire exposure was proved.展开更多
Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typica...Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.展开更多
基金the financial support from the National Natural Science Foundation of China-Joint Fund Project(Grant No.U1834208).
文摘When a fire occurs in an underground shield tunnel,it can result in substantial property damage and cause permanent harm to the tunnel lining structure.This is especially true for large-diameter shield tunnels that have numerous segments and joints,and are exposed to specific fire conditions in certain areas.This paper constructs a full-scale shield tunnel fire test platform and conducts a non-uniform fire test using the lining system of a three-ring large-diameter shield tunnel with an inner diameter of 10.5 m.Based on the tests,the tem-perature field distribution,high-temperature bursting,cracking phenomena,and deformation under fire conditions are observed.Fur-thermore,the post-fire damage forms of tunnel lining structures are obtained through the post-fire ultimate loading test,and the corresponding mechanism is explained.The test results illustrate that the radial and circumferential distribution of internal temperature within the tunnel lining,as well as the radial temperature gradient distribution on the inner surface of the lining,have non-uniform dis-tribution characteristics.As a result,the macroscopic phenomena of lining concrete bursting and crack development during the fire test mainly occur near the fire source,where the temperature rise gradient is the highest.In addition,the lining structure has a deformation characteristic of local outward expansion and cannot recover after the fire load is removed.The ultimate form of damage after the fire is dominated by crush damage from the inside out of the lining joints in the fire-exposed area.The above results serve as a foundation for future tunnel fire safety design and evaluation.
文摘Glue-laminated timber(GLT)is an engineered wood product widely used in mass timber construction for its strong structural and fire-resistant properties.However,the fire performance of GLT varies significantly due to the natural and uncertain phenomena(moisture,exposure time,isotropic,homogenous properties,etc.)of fire and timber.This makes it difficult to predict the fire behaviour of the GLT structural elements.To ensure building safety,it is crucial to assess GLT’s fire behaviour and post-fire structural integrity during the design stages.This study conducted the experimental tests of GLT beams(280 mm×560 mm)without loading(1.4 m)and under a four-point bending load(5.4 m).Tests identified thermal behaviour and charring rates of GLT beam.Then,the residual stiffness of the GLT beam was calculated,and the charring rates of the beams were compared with Australian and European standards.Reliability analysis was conducted for beams for a fire exposure of 120 min,considering the charring rates observed through the analysis and simulating the fire insulations.Results show that the charring rate of GLT made with spruce pine timber varied between 0.43 and 0.81 mm/min,with a mean rate of 0.7 mm/min,aligning with both Australian and European standards.However,considering timber density and moisture content,the charring rates in Australian standards were conservative.The study also found that structural capacity significantly degrades under fire,with a 22%reduction in flexural stiffness after 120 min of exposure.Additionally,GLT beams can safely function for 30 min under 75%of their design moment capacity and for 60 min under 50%capacity.
基金Supported by the National Natural Science Foundation of China (Grant No. 50323005)the National Basic Research Program of China (Grant No. 2001CB409603)
文摘Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited,it propagates fire and accelerates the enclosure fire growth. Two types of lining materials were studied during the tests:block board and plywood. The test was conducted in an ISO 9705 room,where linings were mounted on walls without the ceiling. By changing the heat output of the burner,the ventilation,etc.,the concentrations of CO2/CO of different lining materials were researched. The effect of test conditions on the production of CO2/CO of different lining materials was investigated,and useful experimental data were provided for the further development of numerical modeling to simulate enclosure fire growth lined with combusti-ble materials.
文摘To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load test and the other two for the one-side fire tests.Besides,temperature probe points were set on the sandwich walls to obtain the temperature distribution.Meanwhile,the model of the sandwich wall was established in the finite element software by the method of core material stiffness equivalent.The temperature distribution and performance reduction of materials were also considered.The residual bearing capacity of specimens after fire exposure were simulated considering the effects of web spacing,wall panel thickness and fire exposure time.Because the sandwich wall panels were stressed by eccentric compression after a fire,the residual compressive strength of the wall panel after the fire can be calculated through the eccentric loading analysis.Compared with the numerical results,it can be concluded that the effectiveness of calculation method of residual bearing capacity after fire exposure was proved.
基金Project(50706059) supported by the National Natural Science Foundation of ChinaProject(HZ2009-KF05) supported by Open Fund of State Key Laboratory of Fire Science of University of Science and Technology in ChinaProject supported by the Fundamental Research Funds for the Central Universities of China
文摘Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.
