Flame proof systematization design method based on monolithic heavy sectional steel structure

Abstract

The invention relates to a flameproof systemized design method for a whole-based large-scale steel structure in the civil construction engineering technical field, comprising the following steps that: a safe target and a performance index are set; the number of dangerous fire sources and the fire load of various danger areas are calculated, and fire work conditions are designed according to the number of the dangerous fire sources and the fire load of various danger areas; a geometric model is established in simulation software according to the designed fire work conditions, and the mechanical state of a structural system under the condition of real fire disaster is obtained through numerical simulation; judgment is made according to the numerical simulation result; if the structure fails, the structural design is readjusted and flameproof protection is strengthened; simultaneously, a fire scene is adjusted according to a novel design for design until the whole structure does not fail again; key structural members or the danger areas under all the fire work conditions are identified by adoption of the double control method of stress distinguish and deformation distinguish, and examination is made whether stress and deformation meet the requirements of the safe performance index. The flameproof systemized design method can accurately reflect real stress states of various structural members in the whole structure under natural fire disaster.

Description

technical field [0001] The present invention relates to a fire protection design method in the technical field of construction engineering, in particular to a systematic design method for fire protection of a large steel structure based on the whole. Background technique [0002] In recent years, all kinds of high-rise, super high-rise and large-space steel structures have developed rapidly and vigorously in China. However, the fire resistance of steel is poor. Under the high temperature of fire, its mechanical properties such as yield strength and elastic modulus will decrease. When the temperature reaches 600°C, it will basically lose all its strength and stiffness. Large-scale steel structures usually have a large building area, spacious space, elegant decoration, many electrical equipment, and great fire hazards. Once a fire occurs, under the action of air convection, it not only burns violently, spreads rapidly, and is not easy to fight, it is easy to cause structural d...

AI Technical Summary

Problems solved by technology

This design method of determining the fire resistance time of a structure based on whether individual components reach the limit state under fire is unrealistic because it does not consider the mutual influence of components in the overall structure

In addition, the fire-resistant design of components based on tests cannot reflect the influence of load distribution and size in actual engineering and the restraint state of components, so it is difficult to reflect the real stress conditions in structural analysis, resulting in unsafe or overly conservative results

[0005] (2) The traditional structural fire resistance research usually uses ISO standard curve or uniform indoor temperature rise curve to simulate the temperature rise process of the structure, which is quite different from the actual fire, so it cannot accurately simulate and analyze the actual fire of the structure reaction

In fact, due to the inhomogeneity of the temperature field distribution in the actual fire, the internal force of the structure is redistributed, often resulting in the readjustment of the entire equilibrium system, and sometimes the structure far away from the fire source will be destroyed first. reflect this holistic

[0006] (3) The performance and response of new structural forms emerging in buildings have not been systematically studied, such as high-rise buildings with strange shapes, large-span reticulated shell structures, and membrane structures, etc.

There is a lack of powerful analytical tools for systematic research on the responses and laws of different structural forms under different fire scenarios

[0007] (4) The current performance-based analysis is still carried out in isolation in the respective fields of fire science and structural engineering. The real impacts of environmental protection, etc. have not been systematically and fully considered, and the changes in the level of danger of the structure and the escape route and time of personnel cannot be considered and evaluated in the same environment.

The shortcomings of this paper: 1. Fire simulation and structural analysis are still relatively independent processes, and the coupling of fire simulation and structural analysis has not been realized, that is, the spatial temperature field cannot be applied to structural analysis, which is a key defect in traditional design methods Where; 2. Structural analysis is still based on a partial framework, and the structural response calculation of the whole space has not been realized; 3. Although the idea of ​​systematic design is proposed, the systematic design process is not given, which is the key to systematic design The technology has not been realized, and the internal relationship between fire action and structural response has not been reflected by technology

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