Ensuring the fire safety of high-performance renewable structural materials is essential for the low-carbon transition of the construction industry. This study investigates the fire resistance of two representative engineered bamboo composites materials: laminated bamboo lumber (LBL) and parallel strand bamboo (PSB). Multiple-stage ISO 834 standard fire tests were conducted, and the results were analyzed using macroscopic charring morphology and cross-sectional temperature field. The study identifies the charring evolution mechanisms, thermal response characteristics, and strength degradation behaviors of both materials under fire. A time-dependent charring depth prediction model is developed, along with a dynamic calibration method for determining the zero-strength layer (ZSL) thickness based on material properties. The findings show that the thermal behavior of LBL and PSB differs substantially from that of wood, indicating that fire design parameters for timber cannot be directly applied to engineered bamboo. The PSB demonstrates superior thermal performance, including more stable char layers, a stronger thermal barrier effect, and lower charring rates, primarily due to its dense restructured morphology and improved compatibility at the fiber-adhesive interfaces. The study further determines a unified critical charring-line temperature of 270 degrees C for both materials. It also reveals, for the first time, the dynamic variation of ZSL thickness with material type, charring depth, and stress state. Overall, this work provides fundamental experimental evidence and material-level parameters that support the application of the Effective Cross-Section Method (ECSM) in the fire-resistant design of engineered bamboo structures.

Building fire safety inspection is a knowledge-intensive engineering task that requires reliable hazard recognition under complex visual conditions, limited labeled data, and strict regulatory accountability. To address these challenges, this paper proposes a coarse-to-fine intelligent inspection framework for building fire hazard recognition and regulation-grounded reporting. The framework first performs binary hazard screening and then refines positive or uncertain cases into specific hazard categories, thereby aligning the inference process with practical inspection workflows. A self-supervised DINOv2 Vision Transformer is adopted as the visual backbone, and a small-sample adaptation strategy is developed by combining staged fine-tuning, a lightweight SE-based classification head, and task-aligned knowledge distillation. In addition, an Agentic RAG compliance layer is introduced to retrieve, verify, and present clause-level regulatory evidence while suppressing hallucinated or unverifiable citations. Experiments on a real-world building fire hazard image dataset show that the proposed framework achieves stable recognition performance, outperforms representative CNN-, supervised Transformer-, and self-supervised Transformer-based baselines, and improves the faithfulness of regulation-grounded reporting. The results suggest that the proposed framework provides a feasible prototype-level pathway toward intelligent and auditable fire safety inspection, while broader multi-site validation and robustness evaluation remain necessary for future deployment.

Addressing the core issue in existing international codes—namely, the inconsistent values of correction factors for edge effects and the failure to account for their dynamic time-dependent characteristics when evaluating the residual load capacity of glued-laminated timber columns after fire—this study conducted systematic fire and axial compression tests. The research revealed a unique temperature rise mechanism in parallel laminated surfaces caused by the elimination of the moisture phase transition plateau due to laminate degradation, while confirming that the evolution of charring depth exhibits isotropy. This study innovatively established a nominal charring depth calculation model that accounts for the time-dependent effects of edge curvature and proposed a method for determining the effective residual cross-section based on the equivalent area method. By integrating this cross-sectional model with the axial compression stability coefficient calculation formulas from multiple national codes, a unified evaluation system was established for the first time, allowing the selection of applicable formulas based on the member’s residual slenderness ratio. Comparative analysis indicates that this system significantly reduces the load-bearing capacity calculation error—which exceeded 30% under the code-based method—to within 10% for different fire exposure durations. The research findings overcome the limitations of current codes that rely on static coefficients, providing a critical modeling foundation and data support for bridging discrepancies among international codes and establishing unified post-fire assessment standards for timber structures. This holds clear engineering value for enhancing the scientific rigor of fire protection design and the precision of post-disaster restoration decisions.

Smart construction, powered by deep human-machine collaboration (HMC), alters risk profiles and introduces complex, subtle hazards, challenging workers’ hazard perception capability (HPC). Current assessment frameworks view hazard perception as a static trait, missing its progressive development in smart construction HMC contexts. They also lack understanding of how key features' influence changes dynamically throughout collaboration stages. This study creates a progressive assessment framework for the four stages of HMC. By comparing three predictive models using data from 550 workers, a highly accurate machine learning-based cascaded model was developed. SHapley Additive exPlanations (SHAP) analysis highlighted that feature importance, such as safety climate and work pressure, changes significantly across stages and revealed non-linear interactions between factors like experience and task complexity. The study reconceptualizes HPC as a stage dependent construct, delivers a robust data-driven assessment model, and highlights stage-specific contributions and interactions among organizational, technological, and behavioral factors.

The parallel strand bamboo (PSB)-laminated bamboo lumber (LBL) composite columns combine the low-carbon and renewable advantages of engineered bamboo with complementary material properties, but their fire-induced charring behavior and post-fire residual capacity remain insufficiently understood. This study conducted ISO 834 standard fire tests and post-fire axial compression tests on PSB-LBL composite columns to investigate the effects of fire exposure time on charring morphology, temperature distribution, charring depth, failure mode, and residual axial capacity. The results show that the charring depth increased bilinearly with exposure time, with nominal charring rates of 0.42 mm/min for the outer PSB layer and 0.86 mm/min for the inner LBL layer. An equivalent charring depth model based on area equivalence was proposed to account for corner rounding and nonuniform cross-sectional loss, giving values approximately 1.04 times the measured charring depth. Furthermore, a post-fire residual axial capacity evaluation method was developed by combining the effective residual cross-section method with stability coefficient from timber design codes. Zonal design recommendations based on the post-fire slenderness ratio were also proposed. The findings provide useful guidance for fire resistance design and post-fire safety assessment of PSB-LBL composite columns.

As a green and low-carbon building material, bamboo meets the sustainable development needs of the construction industry. However, there is still limited research on the fire resistance of bamboo, especially under realistic fire exposure. In this paper, the fire behavior of laminated bamboo lumber (LBL) under two types of realistic fires, the EN 1991-1-2 parametric fires and travelling fires, exposures was investigated, and the relationship between the energy equivalence of imported the LBL specimens and their fire damage equivalence under two types of realistic and standard fires was examined. The results show that if the energy transmitted into the LBL specimens is equivalent, the damage degree of the specimens is also equivalent, thus confirming the validity of the energy equivalence method (EEM) for the LBL, and realizing the transformation of the fire damage evaluation of realistic fires to the one of standard fires. On this basis, the fire performance of the LBL under standard fire was analyzed, and the values of charring rate and charring line temperature of the LBL were determined. Further, the temperature distribution model of pyrolysis region was established, and the calculation model of zero-strength layer (ZSL) thickness considering the fire exposure time, charring rate, fire condition and force condition was proposed. In this way, the quantitative assessment of the LBL damage using the effective cross-section method (ECSM) was realized, and the ECSM was effectively applied in the fire-resistant design of bamboo structures. This study can provide a theoretical basis for the fire-resistant design of bamboo structures, which can help to improve the fire safety of bamboo structures.

In order to improve the fire protection ability of the raised-beam wooden ancient buildings, this paper carries out the fire resistance performance research for its typical dovetail joint nodes. Through the standard fire test and post-fire static loading test on 8 sets of node specimens, the evolution of wood warming characteristics and residual load capacity of nodes were obtained. The results showed that the internal temperature rise of the wood was characterized by three stages, namely "slow-fast-slow", with a turnaround at 100 degrees C and 300 degrees C respectively, and the average charring rate was 0.82 mm/min. With the prolongation of fire time, the increase of charring depth led to the reduction of effective bearing height of tenon and effective section of mortise and tenon; at the same time, the charring of beams and columns also led to the forward shift of purlin rotating pivot point, and the change of load arm caused the increase of overturning moment, which jointly led to the nonlinear attenuation of node residual load bearing capacity. After 30 min of fire, the residual load capacity of specimens Pocketed-Purlin Dovetail Joint (PPDJ) and Elephant-Trunk-Shaped-Beam Dovetail Joint (EBDJ) decreased by 18.45 % and 34.23 %, respectively. A simplified mechanical model of the residual load capacity of dovetail joints after fire was established based on the mortise damage mechanism, and the absolute error between the theoretically calculated values and the test values was less than 9 %. This study quantifies the attenuation law of key nodes subjected to fire, and establishes an assessment model that can provide a basis for the post-fire safety assessment of beam-raising ancient buildings, which is of great practical significance for optimizing fire protection design and post-disaster restoration strategies.

This paper firstly investigated fire dynamics characteristics and the temperature field distributions of large space spherical mesh shell (SMS) structures under localized fire in FDS, and divided the temperature fields into plume region, smoke accumulation region and ceiling jet region. Based on the classical axisymmetric plume model, the predictive models for the steady-state and transient temperature fields in different fire regions for large space SMS structures were proposed in this paper. Thereafter, the proposed temperature models were compared with the simulated results and experimental test results by other scholars, and they were in good agreement. In order to further discover the realistic fire development progress and temperature distribution of large space fire, and validate the proposed temperature field models, this paper designed and conducted three full-scale large space fire tests (Test-1 similar to Test-3) with different fire source powers in a large space building. Results showed that temperature fields of large space fires could be consisted of near-fire region (Flame region) and far-fire region (Plume region and Ceiling jet region). The steady-state fire source powers were tested for 443 kW, 886 kW, 1090 kW for Test-1, Test-2 and Test-3, respectively, while their maximum temperatures of the roof reached 75 degrees C, 105 degrees C and 120 degrees C. Based on McCaffrey plume model, we further proposed the transient temperature model in flame region for large space structures, and its accuracy was verified by the test results. Moreover, the proposed steady-state and transient temperature fields for large space SMS structures were compared with the tested temperature field data, and the tested and predicted temperature curves were generally in good agreement in plume and ceiling jet regions. Finally, the test results aimed to provide a scientific basis and reference for the fire safety and structural fire-resistant design of large space buildings.

In this paper, three full-scale localized wood crib fire tests in a tall-large space building were designed and carried out, and the burning behavior of wood crib fire and their temperature distribution in a large space building were investigated through experimental, simulated and theoretical approaches. The results showed that the temperature field of localized fire in large space could be divided into the flame region, plume region and ceiling jet region, and then their steady-state and transient temperature distributions in each temperature field were discovered and compared. For Test-1, Test-2 and Test-3 with different designed details of wood crib fires, their maximum flame heights were measured as 1.7 m, 5.1 m and 6.1 m during the fire tests, respectively, while the heat release rates (HRRs) were 674 kW, 1568 kW and 2352 kW. Based on the proposed pyrolysis model of wood crib fire in FDS, a combination of ITP (Ignition Temperature Pyrolysis) and SSP (Single-Step Pyrolysis) fire models was used to simulate the burning behavior of wood crib fires in a tall-large space building, and the simulated HRR curves and the temperature field distribution matched up well with the experimental results. Furthermore, a simplified HRR model of wood crib fire was proposed and brought into McCaffrey model, and a temporal and spatial temperature field prediction model of localized wood crib fire in tall-large space buildings was therefore obtained, and the comparative results with the experiment were also good. Finally, the proposed pyrolysis and theoretical models of wood crib fire in this paper could be also used to predict the burning behavior of other similar wood crib fire tests in space, and the research findings of the temperature field distribution law of localized fires in large space could also provide a scientific basis and reference for the fire safety and structural fire-resistant design in tall-large space buildings.

This paper delves into an experimental study on the load-bearing capabilities of self-drilling screw connections in stainless steel studs sheathed with ply-bamboo panels. A total of 92 connection specimens were tested employing monotonic and cyclic loading protocols. The performance of the stainless steel-ply-bamboo connections was studied under various conditions with respect to different ply-bamboo sheathing panels, steel studs, screw features, end distances and loading rates. The failure modes and performance parameters were discussed. The test results obtained in this study indicated that double directional ply-bamboo was lower than unidirectional flat pressing ply-bamboo in terms of tensile properties, and phosphating steel screws (PTS) exhibited higher nominal bending yield moment and yield strength compared to stainless steel screws (STS). In addition, the ultimate deformation of PTS connections was lower than that of STS connections, and the ductility coefficient of PTS connections was higher than that of STS connections. The unidirectional flat pressing ply-bamboo (UF) sheathing connections had a higher tensile strength than double directional ply-bamboo (DL) sheathing connections, but the peak load, the ultimate displacement and the ductility coefficient of the UF sheathing connections exhibited a reduction compared to DL sheathing connections. Stainless steel stud connections had some disadvantages over cold-formed steel stud connections in terms of elastic stiffness and ductility coefficient, but it improved the peak load and ultimate displacement compared to cold-formed steel stud connections. Based on the connection test information, correlation analysis and analytical modeling were conducted on the self-drilling screw connections within lightweight stainless steel-ply-bamboo shear walls.

The addition of prestressing not only improves the force resistance of glulam beams, but also provides a potential solution to improve their fire resistance. An in-depth study of the fire behavior of prestressed glulam beams (PGBs) under fire and the force behavior after fire is essential for their fire resistance design and evaluation. In this paper, fire tests and post-fire four-point bending experiments were conducted on the PGBs aiming to investigate the thermal response of the PGBs as well as their force resistance after fire. The results showed that fire significantly affected the mechanical properties of the PGBs, not only reducing the prestressing force during the fire, but also decreasing the residual load carrying capacity after the fire. After 60 min of standard fire exposure, the prestress and load capacity of the PGBs decreased by 10 % and 33.33 %, respectively. Increasing either prestress or reinforcement ratio can effectively improve the resistance performance of the PGBs after fire. In the same fire action time, if the prestress was increased by 59.46 % or the reinforcement ratio was increased by 0.53 %, the residual ultimate load capacity of the PGBs was increased by 17.14 % and 22.19 %, respectively. The study also indicates that fully utilizing the synergistic effect of prestressing and reinforcement ratio enhancement can significantly improve the overall performance of the PGBs. In addition, a theoretical calculation model is proposed to accurately predict the residual flexural capacity of the PGBs after fire, which provides a theoretical support for the fire-resistant design of the PGBs before fire and the assessment of residual load capacity after fire.

Timber-concrete composite (TCC) structure system is most frequently used in large-span structures. Recently, a performance-based fire safety design method named improved travelling fires methodology (iTFM), which is suitable for long-span structures, has been developed. In this article, an energy-based time equivalent method (EBTEM) is proposed, while its effectiveness is experimentally verified. The proposed method can be used to evaluate the fire resistance of the TCC structures subjected to iTFM fires. The results indicated that the damage degree at different spatial positions of the TCC structure under the same fire size was different, and the location with the least and most serious damages occurs towards the beginning and middle of the fire path, respectively. The results show that this difference in damage degree mainly depends on the fire size, and the difference becomes less pronounced as the fire size increases. Concomitantly, it can be obtained that the damage degree under the different fire sizes was different, and the smaller the fire size, the greater the damage degree. Hence, when the EBTEM is adopted to design the TCC structures exposed to iTFM fires, the setting of fire protection target is largely determined by the actual fire size.

Wood wool cement board is made of Portland cement as a cross-linking agent, wood fiber as a fiber reinforcement material, and some additives. The precast WWCB-filled concrete floor slabs are a new type of hollow slab. This structure formed by pouring the bottom layer of concrete, laying the WWCB, then pouring the top layer of concrete, and finally curing. And this type of floor slabs is composed of double-layer reinforcement mesh, including top and bottom reinforcement which connected by triangular contact bars. In order to study the mechanical properties of the precast WWCB-filled concrete slabs themselves, this paper conducted four-point bending loading tests on 9 precast WWCB-filled concrete slabs of different sizes to analyze the effect of penetration type and cavity size on the flexural performance of the slabs. The results of the experimental study show that: the ultimate load-bearing capacity of precast WWCB-filled concrete slabs is higher than 100-mm-thick solid slabs, and their deflection of them is similar to that of ordinary solid slabs, with good plasticity and flexibility; the overall flexural resistance of the precast WWCB-filled concrete slabs is good, the crack distribution is uniform, and the damage pattern is better than that of cast-in-situ slabs.

This paper conducted series fire tests without load for glulam bolted joints with slotted-in steel plates, where the effects of fire exposure time, fire-retardant coating, fire exposure side and connecting steel bolts number for specimens were considered. Meanwhile, after fire tests, post-fire-performance (PFP) tests were conducted to explore and compare the residual load-carrying capacity and post-fire semi-rigid behavior of the glulam bolted joints with slotted-in steel plates. As a benchmark and comparison, two specimens were also conducted for bending tests without fire exposure. The test results showed that the steel inside the joints including steel box, slotted-in steel plate and steel bolts had a significant effect on the internal temperature distributions and the charring of outer timber. Moreover, the post-fire strength and ductility of the tested specimens decreased with the increase of the fire exposure time, while painting with fire-retardant coating, reducing fire exposure sides and increasing connecting steel bolts for specimens could appropriately increase their residual bending resistance and ductility deformation capacity. Finally, considering the different residual sections for timber after charring under different fire exposure times, a semi-rigid numerical model for the prediction of moment-rotation of the joints after fire exposure was established for the glulam bolted joints with slotted-in steel plates, and the numerical results demonstrated that the predicted moment-rotation curves were in good agreement with the tested curves. The test results could provide a reference for the performance-based fire protection design for timber structures.

The time equivalent method can be used to quantify the fire intensity of a traveling fire into the time of action of the standard fire, which in turn can be used to assess the extent of damage to a structure under a traveling fire. However, an effective time equivalence method for timber structures has not been developed yet. Therefore, this paper proposed an energy-based time equivalent method, referred to as the "energy equivalence method (EEM)", for evaluating the fire resistance of timber structures under traveling fire, and validates its effectiveness through a series of fire tests. The results demonstrate that the EEM effectively quantifies the fire intensity endured by glulam under traveling fire as the equivalent exposure time under the standard fire. Furthermore, the EEM was utilized to investigate the damage behavior of a single-layer Timber-Concrete Composite (TCC) frame under traveling fire. The results reveal variations in the fire intensity experienced by the structure at different locations under the same traveling fire scenario, with the most severe damage occurring at a position 40% relative to the ignition end. The fire scale determines the non-uniformity of the fire intensity and the extent of structural damage, as smaller-scale fires (fire sizes between 10% and 40%) not only result in significant variations in damage levels at different locations but also have a more adverse impact on the structure. In fire safety design, the selection of standard and traveling fire design methods should be based on the fire scale.

The integration of semi-precast concrete beam preparation methods with prestressing structural measures aims to achieve superior mechanical properties while complying with green construction principles. However, the damage mechanism of semi-precast prestressed concrete beams (SP-PCBs) under fire conditions is not clear. In this study, the cross-section temperature distribution, prestressing loss pattern, and residual load-carrying capacity of the SP-PCBs were investigated by conducting standard fire tests. The results show that increasing the thickness of the protective layer of prestressing bars can delay the time of damage by high temperature and thus increase the fire resistance limit of the SP-PCBs. Higher prestressing levels and rebar ratios contribute to the cracking resistance of the SP-PCBs, although the stress loss is obvious. After the fire, the distinct SP-PCBs showed different degrees of reduction in load-carrying capacity and stiffness, but still exhibited excellent fire resistance and avoided brittle damage. Increasing the reinforcing ratio increases the residual load-carrying capacity of the SP-PCBs, while increasing the prestressing level has a relatively small effect. Increasing the height of the post-cast layer slightly reduces the stiffness and ductility of the SP-PCBs, but does not significantly affect the load-bearing capacity. In addition, this paper establishes a theoretical calculation model for the residual load-bearing capacity of the SP-PCBs after the fire, and verifies the accuracy of the model by experimental results, which provides a practical theoretical basis and reference for the design and evaluation of the fire resistance performance of the SP-PCBs.

This paper delves into an experimental study on the load-bearing capabilities of self-drilling screw connections in stainless steel studs sheathed with ply-bamboo panels. A total of 92 connection specimens were tested employing monotonic and cyclic loading protocols. The performance of the stainless steel-ply-bamboo connections was studied under various conditions with respect to different ply-bamboo sheathing panels, steel studs, screw features, end distances and loading rates. The failure modes and performance parameters were discussed. The test results obtained in this study indicated that double directional ply-bamboo was lower than unidirectional flat pressing ply-bamboo in terms of tensile properties, and phosphating steel screws (PTS) exhibited higher nominal bending yield moment and yield strength compared to stainless steel screws (STS). In addition, the ultimate deformation of PTS connections was lower than that of STS connections, and the ductility coefficient of PTS connections was higher than that of STS connections. The unidirectional flat pressing ply-bamboo (UF) sheathing connections had a higher tensile strength than double directional ply-bamboo (DL) sheathing connections, but the peak load, the ultimate displacement and the ductility coefficient of the UF sheathing connections exhibited a reduction compared to DL sheathing connections. Stainless steel stud connections had some disadvantages over cold-formed steel stud connections in terms of elastic stiffness and ductility coefficient, but it improved the peak load and ultimate displacement compared to cold-formed steel stud connections. Based on the connection test information, correlation analysis and analytical modeling were conducted on the self-drilling screw connections within lightweight stainless steel-ply-bamboo shear walls.

Compared with traditional timber boards, timber–concrete composite (TCC) boards demonstrate a higher rigidity and bearing capacity, improved vibration, and better behavior under seismic conditions. However, they become charred when exposed to fire due the combustibility of timber, and the fire safety of this material is considered essential. In this research, 60 min fire exposure tests and residual load-carrying capacity tests following fire exposure were carried out on three full-scale composite boards, two of which were covered with an innovative form of gypsum board protection. The effect of the innovative protection on the temperature field and fire resistance of the TCC boards was studied in detail. The test results indicate that the fire resistance of the TCC boards was effectively improved by using the innovative protection. If the coverage ratio is identical, a wider single gypsum board can demonstrate a slight increase in residual carrying capacity. Finite element models of TCC boards were established to investigate the temperature field during fire exposure and the residual load-carrying capacity of the TCC boards after fire exposure, demonstrating high applicability and accuracy. The conclusions in this paper can provide reference for fire design in engineering.

A detailed characterization of structural damage progress is essential to performance-based seismic design for precast concrete nonrectangular column (PCNC) frame structures. The paper presents an experimental investigation into the damage behavior of the PCNC frame structures under reverse cyclic loading, including specimens PCFS1 and PCFS2 in bay and specimen PCFS3 in depth of a new precast residential building. Based on the experimental results, the damage mechanism of the PCNC frame structures was further discussed with the cumulative energy damage model proposed in this paper, and the influence of key structural parameters on the damage of the PCNC frame structures was examined, including energy dissipation adjusted factor, the residual deformation rate and the stiffness degradation rate. Available results indicated that the experimental damage curves of test specimens increased with the loading progress and acted with nonlinear damage characteristics, and PCNC frame structural damage behavior was sensitive to the axial compression ratio. For the proposed damage model, the calculation results were in good agreement with the experimental results. On the basis, the damage degree of the PCNC frame structures was divided into five performance levels including normal use, temporary use, use after repair, life safety and prevent collapse in the defined damage range of (0, 1). Elastic layer drift ratio limit was suggested to relax for PCNC frame structures. Final test results could provide a basis for the aseismic design and damage assessment of such structures after earthquake.

An energy-based time equivalent method that is capable of converting the fire resistance design of timber components exposed to the realistic fire to that of the standard fire was proposed. To verify the effectiveness of the method applied to the improved Travelling Fires Methodology (iTFM) fires, a series of iTFM fires and their corresponding equivalent standard fire tests were implemented on six glued laminated timber columns. The effectiveness of the method was fully confirmed by comparing the fire effects, the temperature distribution of the pyrolysis layer, and the remaining load-bearing capacity after fire for the timber columns under the iTFM fires and their equivalent standard fires. Meanwhile, it was well illustrated that the adhesive layer was almost no effect on the fire resistance of the timber columns by comparing the cross-sectional temperature distribution, charring depth and charring rate in two directions of the timber columns. To simplify the application of the energy equivalence method, the thermal properties relationships applied to the finite element heat transfer analysis of timber were modified. The accuracy of the modified thermal property relationships was demonstrated by comparing the surface temperature, charring depth, and charring rate obtained from finite element simulations with those measured by the experiment. The simplified energy equivalence method based on the finite element was not only easy for designers to apply, but also helped to promote the development of performance-based fire protection design for timber structures.