The anti -fire design of the steel structure

Huo Yueping (Shandong Liaocheng Public Security Fire Data) steel is not combined, but it is not resistant to refractory. At the high temperature of the fire, the strength and stiffness of the structural steel will be reduced rapidly, so there is no no Fire -resistant steel components are easily damaged in fire.

It can be seen that the fire protection of steel structure is more important than other structures.

It can be found from the previous steel structure building fire cases that occurred in the previous steel structure. Two types of phenomena, one is that the steel structure with fire protection is damaged in the fire that does not reach the expected fire to resist time, and the other is the steel structure with fire protection.

After analysis, these two types of phenomena are caused by the fact that the actual fire heating up and the standard fire warming are inconsistent, but another important reason is that the refractory time determined by the test determined by the test cannot completely represent the refractory time of the component in the structure, so as to thus The consequences of unsafe or conservative material waste.

Therefore, the significance of the fire design of the steel structure by calculating is very significant.

1. The goal of anti -fire resistance is to make the actual refractory time of the structure greater than or equal to the specified refractory limit.

Therefore, for the steel structure, whether it is the anti -fire design of the component or the overall structure, it should meet one of the following requirements. : (1) During the prescribed fire resistance time, the bearing capacity of the structure should not be less than the combined effect generated by various effects; (2) Under the combination of various load effects, the fire resistance time of the structure should not be less than the specified structural refractory resistance. Limits; (3) When the fire is uniform, the critical temperature of the structure reaches the bearing capacity should not be less than the maximum temperature of the structure during the fire resistance. The carrier limit state of the bearing power of the component at high temperature is the refractory limit. Considering the impact of temperature internal force, it can exempt the problems existing in test -based steel structure resistance design methods. It has been widely accepted by various countries and adopted in design specifications.

In China’s first steel structure resistance design standards (1) determined fire prevention measures are used to set a certain amount of thickness.

(2) Calculating component’s firmed fire prevention measures and The internal temperature under the fire resistance limit.

(3) The material parameters of the steel at high temperature are determined to calculate the internal force of the component in the structure under the effect of the load and the temperature of the structure. ) Perform the load effect combination of GT permanent load standard value; OT floor or roof live load (excluding roof snow load) standard value; wind load standard value; temperature changes in AT components or structures The item coefficient, take 1. 7g, the floor or roof live load sub -item coefficient, take 0.\u003e wind load sub -item coefficient, take 0 or 0.3, and select the increasing situation; Effects of wind load and temperature effects Shop coefficient.

(5) According to the type of component and loaded, the refractory carrier bearing bearing state calculation is performed.

The calculation formula is: 5. The upper part of the tower crane must be balanced; in the process, the rotating arm is forbidden; 4. Strictly implement the operating procedures for the top upgrade. ; Vocational inspection personnel have conducted a comprehensive safety technical inspection. After being recognized, they can be delivered after being qualified.

(Received this article: 2003*06*07) For the cross -sectional area of \u200b\u200bthe A -pillar A -pillar of the axis Heart Heart Cardiac, 9T High -temperature lower shaft heart compressive compression component: \u003d a coefficient, according to the length ratio and temperature of the component according to Table 1: (p at room temperature corresponding to the stable coefficient of the chorus column of the cross -section type, according to the current current, according to the current current The relevant provisions of the steel structure design specifications are determined; the yield strength of steel at high temperature at high temperature has the following relationship with the design intensity of steel: F, T’s design intensity at high temperature, according to the design intensity of steel at room temperature The cross -sectional resistance of the component W beam; the overall stability coefficient of the steel beam under CPBT at high temperature; the overall stability coefficient, determined in accordance with the relevant provisions of the current steel structure design specifications.

fyt, f, respectively, the steel of the steel under the high temperature high temperature, respectively. Symbol intensity.

Inside the plane of eccentric compression components: Plane: Power and maximum bending moment; the relevant provisions of the standards are determined; Stability coefficient; the overall stability coefficient of uniform compression components at high temperature; the strength design value of the high temperature under the high temperature; NEXT’s bending moment in high temperature in the plane of Euler in the plane; Elastic modulus.

(6) When the setting of the setting is not appropriate, you can adjust the fire prevention thickness and repeat the above calculation.

A coefficient, press the formula to determine T, steel The average temperature of the beam;

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