On January 21, 2025, a real-time early warning fire-induced collapse test of a two-story steel frame building was successfully conducted in Shanghai by Prof. Guo-Qiang Li's research team from Tongji University. The other institutions participating in the test include Shanghai Fire Science Research Institute of the Ministry of Emergency Management and Shanghai Urban Construction Information Technology Co., Ltd.
Steel buildings are susceptible to collapse under fire, posing a serious threat to the safety of firefighters' lives. Therefore, real-time assessment of the fire-induced collapse risk and accurate prediction of the remaining time to collapse are significant needs to ensure the safety of firefighters and improve rescue efficiency.
Based on the evolution laws of key physical parameters during the collapse process of steel buildings in fire scenarios, Prof. Guo-Qiang Li's research team has innovatively developed a fire-induced collapse real-time early-warning system, centered on real-time perception, online data analysis, and instant forecasting. The effectiveness of the system has been verified in fire tests of a steel portal frame building (2022, Huai'an, Jiangsu, China) and a real steel truss building (2023, Yichang, Hubei, China). The successful implementation of this test has further verified the applicability and robustness of the fire-induced collapse early-warning system for steel buildings in more complex structures.
Fig. 1 Group photo of the team conducting the test.
A two-story steel frame with a regular span of 3 m and a large span of 6 m was employed for the building of this test. The height of each floor is 2.1 m. Four commonly used H-shaped steel sections are utilized for columns and beams. The thickness of the reinforced concrete slabs is 100 mm. A uniformly distributed design load of 3.5 kN/m² (excluding slab self-weight) was applied by sandbags. The fire area is located on the ground floor, enclosed by rock wool sandwich panels with a thickness of 100 mm. Eight stacks of spruce wood (1.5 m×1.0 m×1.5 m) served as the fuel sources.
Fig. 2 The steel frame of the test building.
Fig. 3 Fire load arrangement.
During the test, rotations at different locations of the steel frame were measured using 18 wired inclinometers, of which 16 were placed on steel beams of the top floor, and 2 were installed on the corner column of the ground floor. Based on the measured rotation data, a data reconstruction algorithm was used to perform real-time calculations of the key deformation of the steel frame used in the fire-induced collapse early warning algorithm. Additionally, displacements and temperatures at some locations of the building structure were measured for validation of simulating the test.
Fig. 4 Measurement devices.
Fig. 5 Directly-measured rotations at key locations of the steel frame.
Fig. 6 Directly-measured displacements at key locations of the steel frame.
Fig. 7 Temperatures at some locations of the test building.
The fire was ignited at 10:03:00 am, after which the temperatures inside the fire area continuously increased. At 10:22:24 am, the structure began to collapse after the failure of internal and edge columns exposed to fire. Due to the effects of catenary action and internal force redistribution, the remaining heated steel columns sequentially failed, leading to an inward collapse consistent with expectations. The entire process lasted approximately 20 minutes from fire ignition to the complete collapse of the test building.
Fig. 8 Fire ignition (10:03:00 am).
Fig. 9 Fast-rising phase of fire temperature (10:14:19 am). 
Fig. 10 Initiation of fire-induced building collapse (10:22:24 am).
Fig. 11 Post-fire collapse status of the test building.
During the test, the system successfully issued the early warning of the fire-induced collapse of the test building approximately 150 seconds earlier than its actual collapse in fire.
Fig. 12 Fire-induced collapse early warning system of large steel buildings.