# Theoretical and Numerical Simulation Research on Fire of Large-Span Spatial Structures
Consequently, to facilitate the analysis of the complete response of large space building structures to fire and to provide a heating process that adheres to accuracy requirements, a user-friendly mathematical model for air heating in structural design has been proposed. [PERSON] and [PERSON] et al. [38] employed the fire dynamics software FDS to simulate 120 fire scenarios, regressing a practical empirical formula for air temperature rise in large space building fires, with time, height, and horizontal distance as variables. [PERSON] and [PERSON] [39; 40; 41] utilized FDS to simulate fire scenes and established a Logistic model function for the air temperature rise curve in large space building fires. [PERSON] and [PERSON] [42; 43] derived a novel large space fire heating model from full-scale tests and FDS simulations, uniquely incorporating the cooling phase of fire in its later stages. These three models consider fire temperature as a function of vertical position (z), horizontal position (x), and time (t). [PERSON]'s model, despite its initial proposal and widespread application, was criticized for its complex parameters and neglect of ventilation effects. [PERSON]'s model, while simpler and with a good fit, accounts for the smoke exhaust system's role. Notably, only [PERSON]'s model predicts the late-stage fire attenuation. The widespread application of large-span spherical dome steel structures contrasts with the scarcity of research on their fire behavior, particularly in the context of open-top smoke exhaust systems. Despite the occurrence of fires and the consequent demand for advanced fire protection design, there is a significant disparity between the structural application and the development of fire safety measures. Variations in the area of air supply ports significantly impact the natural smoke exhaust volume and the fire temperature field within these spaces. Current temperature calculation models, which are empirically derived from numerous examples, lack detailed parameter values for specific fire scenarios, making it challenging to accurately apply them to different models, such as those with distinct smoke exhaust configurations. The accuracy of these models is largely contingent upon the highest temperature value \(T_{\text{max}}\) directly above the fire source. While the two-zone model predictor is extensively used and suitable for a variety of fire scenarios, it and other current large space, two-region prediction models fail to account for temperature distribution, assuming uniformity. In large space buildings with top openings, this assumption no longer holds, as temperature distribution becomes non-uniform. The existing calculation models provide only average temperatures and do not capture the temperature gradients at different heights throughout the fire event. The impact of varying natural air supply areas on the fire temperature field and smoke flow within a spherical dome space building is examined in this study, utilizing a 60 m-span structure with natural smoke exhaust as the model. The two-region model concept is applied to analyze smoke flow and heat transfer in the space during a fire, and to investigate the spatial temperature field distribution characteristics of the spherical dome structure under such conditions. The spatial temperature field distribution is simplified through this analysis to develop a method for calculating the maximum temperature attainable within the spherical dome space structure during a fire. A logarithmic curve model is derived that describes the maximum temperature as a function of vertical height post-fire. This approach, characterized by its low computational complexity, provides accurate predictions of maximum temperatures attainable in various fire scenarios. This research provides a comprehensive analysis that integrates theoretical insights with empirical data, culminating in a model that is both scientifically robust and practically applicable.