Hainan Steel teach you: the construction of fire-resistant structure function analysis

Functional Analysis of the construction of fire-resistant construction

The primary factors that describes the characteristics of the primary structure in the form of construction and fire-resistant construction features a variety of construction, the impact of the construction of fire-resistant construction features, construction and construction under fire Definition member extreme conditions, the construction of fire-resistant construction accounting approach chosen model and accounting step steel structure and concrete structure of refractory time accounting methods, all the fire-resistant construction accounting approaches and steps.

First, the impact of the construction of fire-resistant construction features Factors

(A) construction type

1. Steel Construction

Steel structure is constructed of steel production, including steel frame construction, steel truss structure and steel shell structure, large span cross - beam structure. Steel structure with a high degree of mechanization of construction, earthquake resistance and good, but the biggest drawback of the steel structure is fire-resistant function is poor, need to take fire prevention measures coated steel structure fire coatings can withstand fire must be planned. Based on the construction of tall steel structure in space, during the steel structure fire-resistant function analysis, if the temperature of the steel structure under fire around the lower, and to adhere to safety construction, the steel structure may not need to take fire prevention measures.

2. The reinforced concrete structure

Reinforced concrete structure is configured in reinforced concrete structure constituted the first pressure-receiving concrete, reinforced prime accepts Rally, which together bear the load. When the high importance of the construction of fire-resistant construction, fire load greater occupant density greater force structure or construct complex situations, the reinforced concrete structure fire can also be dissatisfied with demand. In this case, the need for reinforced concrete structure and components of refractory functional assessment to determine the structure of refractory functional needs are not satisfied.

3. steel - concrete composite structure

(1) steel reinforced concrete structure. Steel reinforced concrete structure is embedded in the steel reinforced concrete structure consisting of a combination of structure-section as shown in Figure 5-4-15. Suitable for large span, heavy-duty construction. Because steel is concrete wrapped in fire low temperature steel, steel reinforced concrete structure fire function better.

(2) steel concrete construction. Concrete pipe is made of steel and concrete structure composed of two materials, which give full play to the advantages of the two materials steel and concrete, with a carrying capacity of high ductility and good. Concrete pipe configuration, due to the presence of concrete can reduce the temperature of the steel pipe, steel pipe temperature than without concrete is much lower. Normally, concrete steel structure of steel required for fire protection. Steel concrete column section shown in Figure 5-4-16.

(B) the load ratio

Constructs load ratio of load to bear its ultimate load ratio. Under fire, the same general structure accepts loads, but with increasing temperature, the material strength is lowered, the bearing member can be reduced. When the load reaches the ultimate load member, member reached the carrying capacity under fire, the fire resistance of members reached the situation, the destruction began to collapse, then the time of the fire resistance of fire. Load ratio, the fire resistance of members of the smaller load ratio is one of the primary factors that affect the structure and function of the element fire.

(C) fire plan

Fire planning including fire temperature and fire duration. Fire is the source of high temperature heating elements, which heat through convection and radiation are two ways to transfer heat from the air to build within member. As drivers member warming, fire plan have a significant effect on the temperature distribution field. When exposed to fire lasts longer, the heating element is also higher.

(D) the structure and components temperature field

The higher the temperature, the more severe deterioration of the material features, temperature field structure and components is one of the primary factors affecting the function of the refractory. Thermal functional materials directly affects the speed of heating member, thus determining the temperature field under fire structure and components of the distribution.

Second, the intent of the refractory structure function analysis and criteria

Refractory structure functional analysis intention is to construct and member of refractory checking function is not satisfied with the current specification requirements. Refractory structure function analysis are usually two ways: first checking the fire resistance of the structure and components are not satisfied with the specification requirements; the second that is in effect the fire resistance of fire temperature field when the specification, structure and components load carrying capacity is not greater than the effect of the combination. These two approaches are equivalent.

(A) fire resistance of demand

Fire resistance of demand components should follow the "build fire protection design" GB50016, consistent "senior civil construction fire protection design" GB50045 and other relevant national standards requirements.

(B) the member status of the design requirements FIRE RESISTANT

"The construction of steel structure fire technical specifications" (GB issued) proposed anti-fire way checking accounts based structure and components. The probability of fire is very small, is an occasional load conditions. Therefore, under the fire of checking standard configuration can be relaxed. According to "the construction of steel structure fire protection technical specifications" (GB issued), under fire only to limit the status of all bearer structure or member of the checking, no checking extreme conditions of normal use. Carrying capacity limit condition of the structure include the following situations:

① axial force component section yield;

② flexural members produce enough plastic hinges and become variable mechanism;

③ member all lose stability;

④ members continue to carry achieve suitable deformation. Built on the usual structure that can host only to members checking on the construction of major construction but also for the whole structure of the carrying capacity checking.

Third, the accounting model

Construction of fire-resistant construction features accounts (also commonly referred to as anti fire checking) usually have three ways when checking anti-fire: the first model to take account of all structure; the second model to take account of the sub-structure; and the third to take a single member accounting model. "The construction of steel structure fire technical specifications" (CECS200: 2006) and local standards in Guangdong Province, "the construction of fire-resistant design specification for concrete structure" (DBJ / T 15-81-2011) provisions concerning the construction of a height greater than the top 100m of construction should adopt all accounting model accounting structure fire resistance, single and multi-structure can be built only member of the anti-fire checking.

The actual construction of structure, the member always interact with other members, independent members are non-existent. Therefore, the research component of refractory functional boundary conditions need to be considered members. European specification, conduct element fire function analysis, boundary conditions member desirable by the boundary conditions before the fire, and in the process by the fire remained unchanged. Hainan Steel