CN105223231A - The test method of test expanding fire-proof paint effective thermal expansion coefficient - Google Patents

Abstract

The present invention relates to a kind of method of testing of expanding fire-proof paint effective thermal expansion coefficient.The method is based on the standard fire test of expanding fire-proof paint protection steel beam column; can the actual performance of concentrated expression expanding fire-proof paint under fire; the intensification that greatly simplify steel beam columns under fire condition component calculates, and the effective thermal expansion coefficient of expanding fire-proof paint can be expressed as the linear function about thickness and cross section shape coefficient.Test shows with the contrast of theory calculate; adopt effective thermal expansion coefficient quite accurately can simulate the expanding fire-proof paint protection intensification of steel beam column under fire, for the delivery receiving acceptance of expanding fire-proof paint and steel beam columns under fire condition component heat up calculate significant.

Description

The test method of test expanding fire-proof paint effective thermal expansion coefficient

Technical field

The present invention relates to Fire-resistance of Steel Structures field of engineering technology, particularly relate to a kind of test method of testing expanding fire-proof paint effective thermal expansion coefficient.

Background technology

The fire resistance of steel construction is poor; its reason mainly contains two aspects: one is that steel strength raises with temperature and reduces rapidly; two is that steel heat transmissibility factor is very large; steel beam columns under fire condition component quick heating; fire resistance period without the steel beam column of flameproof protection is generally only 15 ~ 20min, therefore very easily destroys under fire.In order to prevent and reduce the fire hazard of construction steel structure, all need in most cases to carry out flameproof protection to steel construction.Expanding fire-proof paint is widely used in steel structure fireproofing engineering because it has the advantage such as light weight, good decorating effect.

The temperature in fire scope of expanding fire-proof paint under fire is very large, more than normal temperature to 1000 DEG C.In this temperature range, expanding fire-proof paint expands, and thickness and heat-conduction coefficient have a greater change.Therefore, adopt the heat-conduction coefficient under normal temperature to calculate the temperature of steel beam column under fire and will cause larger error.But from application of engineering project, owing to being only concerned about the temperature of component at a time (when especially reaching fire endurance) in resisting fire design, so just can cast aside the heat-conduction coefficient of fireproof coating, and the temperature of component is calculated with an equivalent heat-conduction coefficient, heat-conduction coefficient adopts a constant greatly can simplify calculating.

In sum, study a kind of test and computing method of the fireproof coating effective thermal expansion coefficient based on standard intensification fire test, for the delivery receiving acceptance of fireproof coating and steel beam columns under fire condition component heat up calculate significant.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of test method of testing expanding fire-proof paint effective thermal expansion coefficient, overcomes the above-mentioned technical matters existed in prior art.

The present invention tests the test method of Non-expansive fireproof paint effective thermal expansion coefficient, the effective thermal expansion coefficient of expanding fire-proof paint is the mean value of all heat-conduction coefficient between test specimen temperature 400 ~ 600 DEG C, and the concrete steps of the heat-conduction coefficient of each temperature of test test specimen are:

A. the steel beam column of expanding fire-proof paint will be applied as test specimen;

B. test specimen is placed in Fire Furnace, carries out standard fire test, test in-furnace temperature T _gwith test specimen temperature T _s, and record in-furnace temperature T _g-heating-up time t relation curve and test specimen temperature T _s-heating-up time t relation curve;

C. in conjunction with the surface area A of test specimen unit length _p, the volume V of test specimen unit length, the thickness d of fireproof coating _pand the test specimen temperature T recorded in step b _s-heating-up time t relation curve, according to the heat-conduction coefficient λ of following formulae discovery fireproof coating, and records heat-conduction coefficient λ-test specimen temperature T _srelation curve:

$\mathrm{\λ}=d_p{c}_s{\mathrm{\ρ}}_s.\frac{V}{A_p}\·\frac{T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)}{\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t}---\left(1\right)$

T in formula---the heating-up time, s;

Δ t---time step, s, generally should not be greater than 5s;

T _g---the temperature of surrounding air, DEG C;

T _s---the test specimen temperature in fire test, DEG C;

ρ _s---the density of steel, kg/m3;

C _s---the specific heat capacity of steel, J/ (kgK);

A _p---the surface area of test specimen unit length, m ²/ m;

V---the volume of test specimen unit length, m ³/ m;

D _p---the thickness of expanding fire-proof paint, m;

The heat-conduction coefficient of λ---expanding fire-proof paint, W/ (mK);

Below the derivation principle of above-mentioned formula and process are described in detail:

For the steel beam column of the employing expanding fire-proof paint protection that fire lower surface is heated evenly, can build according to Lumped-Capacity method principle

Vertical component inside intensification iterative computation formula, formula is as follows:

$T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)=\frac{\mathrm{\α}}{{\mathrm{\ρ}}_s{c}_s}\·\frac{A_p}{V}\·\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t---\left(2\right)$

$\mathrm{\α}=\frac{1}{\frac{1}{{\mathrm{\α}}_c+{\mathrm{\α}}_r}+\frac{d_p}{\mathrm{\λ}}}---\left(3\right)$

α in formula---combined heat transfer coefficient, W/ (m ³k);

α _c---the thermal convection heat transfer coefficient between air and component surface, a _c=25W/ (m ²k);

α _r---the heat radiation heat transfer coefficient between air and component surface, W/ (m ²k);

Formula (2), (3) draw from document: ①Li Guoqiang, Han Linhai, Lou Guobiao, Jiang Shouchao. the resisting fire design [M] of steel construction and steel-concrete combined structure. and Beijing: China Construction Industry Press, 2006.

2. CECS200:2006 construction steel structure fireproofing technique specification [S].CECS200:2006,Technicalcodeforfiresafetyofsteelstructureinbuildings,ChinaAssociationforEngineeringConstructionStandardization,ChinaPlanningPress,Beijing,2006；

③EN1993-1-2.Eurocode3:Designofsteelstructures–Part1-2:Generalrules–Structuralfiredesign[S],2005。

Usually, the d/ λ of fireproof jointing sheath is much larger than 1/ (α _r+ α _c), then complex heat transfer coefficient α can be similar to and be calculated as follows:

$\mathrm{\α}=\frac{\mathrm{\λ}}{d}---\left(4\right)$

Formula (2) can be written as:

$T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)=\frac{\mathrm{\λ}/d}{{\mathrm{\ρ}}_s{c}_s}\·\frac{A_p}{V}\·\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t---\left(5\right)$

Formula (5) is changed, formula (1) can be obtained.Therefore according to the surface area A of known test specimen unit length _p, the volume V of test specimen unit length, the thickness d of fireproof coating _pand the test specimen temperature T recorded in step b _s-heating-up time t relation curve, substitutes into the heat-conduction coefficient λ that formula (1) calculates fireproof coating, and records heat-conduction coefficient λ-test specimen temperature T _srelation curve:

D. the effective thermal expansion coefficient of expanding fire-proof paint is calculated as follows:

${\mathrm{\λ}}_{ea}=\frac{1}{200}\·\underset{T_s=400}{\overset{T_s=600}{\∫}}\mathrm{\λ}\left(T_s\right){\mathrm{dT}}_s---\left(6\right)$

λ _e＝1.2λ _ea(7)

λ in formula _ea---expanding fire-proof paint at steel beam column temperature 400 ~ 600 DEG C of average conduction coefficients, W/ (mK);

λ _e---the effective thermal expansion coefficient of expanding fire-proof paint, W/ (mK);

E. the effective thermal expansion coefficient of intumescent coating is fitted to the linear relationship of coating thickness and cross section shape coefficient:

${\mathrm{\λ}}_e(d_p,\frac{A_p}{V})=C_0+C_1\·d_p+C_2\·\frac{A_p}{V}---\left(8\right)$

C in formula ₀---linear regression gained intercept, W/ (mK);

C ₁---linear regression gained slope, W/ (m ²k);

C ₂---linear regression gained slope, W/K.

F. the effective thermal expansion coefficient of expanding fire-proof paint is adjusted in adjustment region:

λ in formula _e-adj---the effective thermal expansion coefficient after adjustment, W/ (mK);

The residual error standard deviation of σ---effective thermal expansion coefficient, W/ (mK).

Preferably, described test specimen temperature T _sobtained by the diverse location mean value measuring described steel beam column.

Preferably, the cross section shape coefficient of I shape test specimen (comprising grooved test specimen), consider the shadow effect in cross section.

Preferably, the fire resistance period test specimen chosen in described step a applying expanding fire-proof paint is the fire resistant coating of 0.5h, 1.0h, 1.5h thickness.

By above technical scheme, the present invention proposes concept and the method for testing thereof of the effective thermal expansion coefficient of expanding fire-proof paint.The method is based on the standard fire test of expanding fire-proof paint protection steel beam column; can the actual performance of concentrated expression expanding fire-proof paint under fire; the intensification that greatly simplify steel beam columns under fire condition component calculates, and the effective thermal expansion coefficient of expanding fire-proof paint can be expressed as the linear function about thickness and cross section shape coefficient.Test shows with the contrast of theory calculate; adopt effective thermal expansion coefficient quite accurately can simulate the expanding fire-proof paint protection intensification of steel beam column under fire, for the delivery receiving acceptance of expanding fire-proof paint and steel beam columns under fire condition component heat up calculate significant.

Accompanying drawing explanation

Fig. 1 is test steel plate test specimen used diagram, in figure, 1,2,3-steel beam column point for measuring temperature;

Fig. 2 is test joist steel test specimen used diagram, in figure, 1,2,3-steel beam column point for measuring temperature;

Fig. 3 is test joist steel test specimen used diagram, in figure, 1,2,3-steel beam column point for measuring temperature;

Fig. 4 records heating curve comparison diagram with steel plate test specimen heating curve and the test of the method prediction proposed, and in figure, P-0601, P-09-1, P-15-1 are that test specimen is numbered, corresponding with table 2;

Fig. 5 records heating curve comparison diagram with joist steel test specimen 1 heating curve and the test of the method prediction proposed, and in figure, HN1-06-1, HN1-09-1, HN1-15-3 are that test specimen is numbered, corresponding with table 2;

Fig. 6 records heating curve comparison diagram with joist steel test specimen 2 heating curve and the test of the method prediction proposed, and in figure, HN2-06-2, HN2-09-3, HN2-15-3 are that test specimen is numbered, corresponding with table 2.

Embodiment

By particular specific embodiment, embodiments of the present invention are described below, person skilled in the art scholar the content disclosed by this instructions can understand other advantages of the present invention and effect easily.

Refer to Fig. 1 to Fig. 2.Notice, structure, ratio, size etc. that this instructions institute accompanying drawings illustrates, content all only in order to coordinate instructions to disclose, understand for person skilled in the art scholar and read, and be not used to limit the enforceable qualifications of the present invention, therefore the not technical essential meaning of tool, the adjustment of the modification of any structure, the change of proportionate relationship or size, do not affecting under effect that the present invention can produce and the object that can reach, still all should drop on disclosed technology contents and obtain in the scope that can contain.Simultaneously, quote in this instructions as " on ", D score, "left", "right", " centre " and " one " etc. term, also only for ease of understanding of describing, and be not used to limit the enforceable scope of the present invention, the change of its relativeness or adjustment, under changing technology contents without essence, when being also considered as the enforceable category of the present invention.

For a better understanding of the present invention, following calculated examples is provided:

Test a kind of effective thermal expansion coefficient of expanding fire-proof paint, concrete steps are:

A. the steel beam column of Non-expansive fireproof paint will be applied as test specimen.One, the steel plate (shown in Fig. 1) that steel beam column is dimensions length is 200mm, width is 270mm, thickness is 16mm.Its two, i-shape component one is wide 200m, high 400mm, edge of a wing thickness 16mm, web thickness 12mm.Its three, i-shape component two is wide 200m, high 400mm, edge of a wing thickness 20mm, web thickness 16mm (Fig. 2 shown in).Thickness test specimen applying expanding fire-proof paint is 0.6mm, 0.9mm, 1.5mm.

Table 1

B. test specimen is placed in Fire Furnace, carries out standard fire test, test in-furnace temperature and test specimen temperature T _s, and record in-furnace temperature-heating-up time t relation curve and test specimen temperature T _s-heating-up time t relation curve.Test specimen temperature T _sobtained by the diverse location mean value measuring above-mentioned steel plate.

C. in conjunction with the surface area A of test specimen unit length _p, the volume V of test specimen unit length, the thickness d of fireproof coating _pand the test specimen temperature T recorded in step b _s-heating-up time t relation curve, according to the heat-conduction coefficient λ of following formulae discovery fireproof coating, and records heat-conduction coefficient λ-test specimen temperature T _srelation curve:

$\mathrm{\λ}=d_p{c}_s{\mathrm{\ρ}}_s.\frac{V}{A_p}\·\frac{T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)}{\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t}---\left(1\right)$

T in formula---the heating-up time, s;

T _g---the inner flue gas of the stove temperature in fire test, DEG C;

T _s---the test specimen temperature in fire test, DEG C;

A _p---the surface area of test specimen unit length, m ²/ m;

V---the volume of test specimen unit length, m ³/ m;

D _p---the thickness of expanding fire-proof paint, m;

The heat-conduction coefficient of λ---expanding fire-proof paint, W/ (mK);

D. get the effective thermal expansion coefficient of mean value as Non-expansive fireproof paint of all heat-conduction coefficient between test specimen temperature 400 ~ 600 DEG C, and get the safety coefficient of 1.2 times.

${\mathrm{\λ}}_{ea}=\frac{1}{200}\·\underset{T_s=400}{\overset{T_s=600}{\∫}}\mathrm{\λ}\left(T_s\right){\mathrm{dT}}_s---\left(2\right)$

λ _e＝1.2λ _ea(3)

λ in formula _ea---expanding fire-proof paint at steel beam column temperature 400 ~ 600 DEG C of average conduction coefficients, W/ (mK);

λ _e---the effective thermal expansion coefficient of expanding fire-proof paint, W/ (mK);

Table 2

E. linear fit is carried out to gained effective thermal expansion coefficient, obtains:

$\begin{array}{cc}{\mathrm{\λ}}_e=0.0244+0.0065\·d_p-1.5714\·\frac{A_p}{V}\·{10}^{-4}& (W/(m\·K))\end{array}$

σ＝0.0011(W/(m·K))

F. gained effective thermal expansion coefficient is adjusted, obtains:

Adjustment region is: cross section shape coefficient>=142m ^-1and DFT≤0.8mm; Cross section shape coefficient≤88m ^-1and DFT>=1.2mm.

G. with the effective thermal expansion coefficient after adjustment, carry out intensification calculate by following formula (4) to steel beam column, the heating curve obtained is with testing the test specimen temperature T recorded _s-heating-up time t relation curve contrasts, as Figure 4-Figure 6.Known prediction heats up and test heats up coincide very well within the scope of 400 ~ 600 DEG C, because expanding fire-proof paint has formed stable coating more than 600 degree, therefore also can record better more than 600 degree in advance, the intensification that this method may be used within the scope of steel beam column temperature 400 ~ 800 DEG C calculates.

$T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)=\frac{\mathrm{\λ}/d}{{\mathrm{\ρ}}_s{c}_s}\·\frac{A_p}{V}\·\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t---\left(4\right)$

In sum, the present invention, according to the component heating curve of steel beam column standard fire test record, can obtain the relation curve between heat-conduction coefficient and test specimen temperature according to formula scales.Because heat-conduction coefficient changes with temperature, component is heated up and calculates inconvenience.The present invention is on the basis of test, the concept of effective thermal expansion coefficient is proposed, namely adopt a representational constant as the effective thermal expansion coefficient of fireproof coating, and effective thermal expansion coefficient is expressed as the linear function relevant to coating thickness and cross section shape coefficient.So the present invention effectively overcomes various shortcoming of the prior art and tool high industrial utilization.

Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.

Claims (6)

1. test the test method of expanding fire-proof paint effective thermal expansion coefficient for one kind, it is characterized in that, the effective thermal expansion coefficient of expanding fire-proof paint is 1.2 times of the mean value of all heat-conduction coefficient between test specimen temperature 400 ~ 600 DEG C, effective thermal expansion coefficient is expressed as the linear relationship of coating thickness and cross section shape coefficient, and concrete steps are:

A. test specimen is placed in Fire Furnace, carries out standard fire test, test in-furnace temperature T _gwith test specimen temperature T _s, and record in-furnace temperature T _g-heating-up time t relation curve and test specimen temperature T _s-heating-up time t relation curve;

B. in conjunction with the surface area A of test specimen unit length _p, the volume V of test specimen unit length, the thickness d of fireproof coating _pand the in-furnace temperature T recorded in step a _g-heating-up time t relation curve and test specimen temperature T _s-heating-up time t relation curve, according to the heat-conduction coefficient λ of following formulae discovery fireproof coating, and records heat-conduction coefficient λ-test specimen temperature T _srelation curve:

$\mathrm{\λ}=d_p{c}_s{\mathrm{\ρ}}_s\·\frac{V}{A_p}\·\frac{T_s(t+\mathrm{\Δ}t)-T_s\left(t\right)}{\[T_g(t+\mathrm{\Δ}t)-T_s\left(t\right)\]\mathrm{\Δ}t}---\left(1\right)$

T in formula---the heating-up time, s;

T _s---the test specimen temperature in fire test, DEG C;

A _p/ V---test specimen cross section shape coefficient, m ^-1;

A _p---the surface area of test specimen unit length, m ²/ m;

V---the volume of test specimen unit length, m ³/ m;

D _p---the initial build of expanding fire-proof paint, m;

The heat-conduction coefficient of λ---expanding fire-proof paint, W/ (mK);

C. the effective thermal expansion coefficient of expanding fire-proof paint is calculated as follows:

${\mathrm{\λ}}_{ea}=\frac{1}{200}\·\underset{T_s=400}{\overset{T_s=600}{\∫}}\mathrm{\λ}\left(T_s\right){\mathrm{dT}}_s---\left(2\right)$

λ _e＝1.2λ _ea(3)

λ in formula _ea---expanding fire-proof paint at steel beam column temperature 400 ~ 600 DEG C of average conduction coefficients, W/ (mK);

λ _e---the effective thermal expansion coefficient of expanding fire-proof paint, W/ (mK);

D. the effective thermal expansion coefficient of expanding fire-proof paint is fitted to the linear relationship of coating thickness and cross section shape coefficient:

${\mathrm{\λ}}_e(d_p,\frac{A_p}{V})=C_0+C_1\·d_p+C_2\·\frac{A_p}{V}---\left(4\right)$

C in formula ₀---linear regression gained intercept, W/ (mK);

C ₁---linear regression gained slope, W/ (m ²k);

C ₂---linear regression gained slope, W/K;

E. the effective thermal expansion coefficient of expanding fire-proof paint is adjusted in adjustment region:

λ in formula _e-adj---the effective thermal expansion coefficient after adjustment, W/ (mK);

The residual error standard deviation of σ---effective thermal expansion coefficient, W/ (mK).

2. the test method of test expanding fire-proof paint effective thermal expansion coefficient according to claim 1, is characterized in that, test test specimen at least comprises 3 groups of cross section shape coefficients and 3 groups of coating thicknesses.

3. the test method of test expanding fire-proof paint effective thermal expansion coefficient according to claim 1, is characterized in that, described test specimen temperature T _sobtained by the mean value measuring described steel beam column diverse location temperature, each test specimen measuring point at least 3.

4. the test method of test expanding fire-proof paint effective thermal expansion coefficient according to claim 1, is characterized in that, the cross section shape coefficient of I shape test specimen (comprising grooved test specimen), and consider the shadow effect in cross section, circular is:

${\[A_p/V\]}_c=\frac{2(b+h)}{V}---\left(6\right)$

B in formula---I shape test specimen (comprising channel-section steel) cross-sectional width, m;

H---I shape test specimen (comprising channel-section steel) depth of section, m;

[A _p/ V] _c---revised cross section shape coefficient, m ²/ m.

5. the test method of test expanding fire-proof paint effective thermal expansion coefficient according to claim 1, is characterized in that, the effective thermal expansion coefficient of expanding fire-proof paint is fitted to the linear relationship of coating thickness and cross section shape coefficient.

6. the test method of test expanding fire-proof paint effective thermal expansion coefficient according to claim 1, is characterized in that, adjusted by the effective thermal expansion coefficient of expanding fire-proof paint in adjustment region, to meet the requirement of safe design.