CN106529068B - The glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration - Google Patents
The glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration Download PDFInfo
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- 239000002023 wood Substances 0.000 title claims abstract description 51
- 238000013461 design Methods 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000009970 fire resistant effect Effects 0.000 title claims abstract description 16
- 238000004026 adhesive bonding Methods 0.000 claims abstract description 24
- 238000009826 distribution Methods 0.000 claims abstract description 22
- 238000004458 analytical method Methods 0.000 claims abstract description 16
- 229920005610 lignin Polymers 0.000 claims abstract description 9
- 230000006866 deterioration Effects 0.000 claims abstract description 6
- 238000012546 transfer Methods 0.000 claims abstract description 6
- 238000000197 pyrolysis Methods 0.000 claims description 24
- 230000015556 catabolic process Effects 0.000 claims description 13
- 238000006731 degradation reaction Methods 0.000 claims description 13
- 238000004364 calculation method Methods 0.000 claims description 9
- 230000005855 radiation Effects 0.000 claims description 9
- 230000006835 compression Effects 0.000 claims description 8
- 238000007906 compression Methods 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 8
- 230000009467 reduction Effects 0.000 claims description 7
- 239000003292 glue Substances 0.000 claims description 6
- ONUFESLQCSAYKA-UHFFFAOYSA-N iprodione Chemical compound O=C1N(C(=O)NC(C)C)CC(=O)N1C1=CC(Cl)=CC(Cl)=C1 ONUFESLQCSAYKA-UHFFFAOYSA-N 0.000 claims description 4
- 240000002853 Nelumbo nucifera Species 0.000 description 8
- 235000006508 Nelumbo nucifera Nutrition 0.000 description 8
- 235000006510 Nelumbo pentapetala Nutrition 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 241000218652 Larix Species 0.000 description 3
- 235000005590 Larix decidua Nutrition 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000003763 carbonization Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
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- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
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- 231100000517 death Toxicity 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000009510 drug design Methods 0.000 description 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
Abstract
The invention discloses the glued pin fire resistant design methods that low-temperature space strength of wood in consideration deteriorates, and belong to resisting fire design field.Method includes the following steps: glued pin cross section finite element Analysis of heat transfer, glued pin cross-section temperature field distribution under the conditions of for obtaining the standard fire curve as defined in international standard ISO834；According to wood lignin by thermal characteristics, timber high temperature rift grain relative compressive strength multi-ladder simplified model is established, determines the representative section of gluing pin cross section；It determines laminated wood columns bearing capacity, carries out the fire resistance analysis and design of glued pin.The present invention is by establishing timber high temperature rift grain relative compressive strength multi-ladder simplified model and glued pin cross-section temperature field distribution, and the representative section by glued pin cross section during fire, propose the glued pin fire resistant design method of low-temperature space strength of wood deterioration in considering；Meanwhile it also realizing and glued pin fire endurance is estimated.
Description
Technical field
The present invention relates to glued pin resisting fire designs, and in particular to the glued pin that low-temperature space strength of wood deteriorates in consideration
Fire resistant design method.
Background technique
The natural resources that timber is produced as terrestrial ecosystem belongs to negative carbon construction material, because Wood products are solid
The carbon of change, it is more than the carbon that it is discharged in the production and use process.Therefore, the multiselect timber in construction material will help
Inhibit CO in atmosphere2The growth of content, the trend that mitigation of global climate warms have important meaning to the survival and development of the mankind
Justice.With the continuous development of timber processing scientific and technological level, laminated wood is at the best product for replacing traditional solid sawn lumber product.It is glued
Wood is the rationally timber production laminate using small cross sections, then the glued big section structural member being fabricated to, and reduces timber and naturally lacks
The adverse effect to component strength is fallen into, scantling and shape breach the limitation of natural timber.It is manufactured and is used using laminated wood
The heavy timber construction house of beam column construction system, there is component to prepare, and the pleasant lively affinity of economical and efficient, appearance is strong, Interior Space
Between arrange freedom and flexibility the advantages that, be increasingly taken seriously.
Although glue laminated wood member there are many merits, since timber itself has combustibility, combustible in building is increased
Quantity, increase risk.No matter traditional architecture or modern architecture, the generation of fire can all cause economic loss and personnel
Injures and deaths, therefore, the rational design of laminated structure part fire resistance have great significance.Usual laminated wood columns bearing capacity loss master
To include 2 aspects: the intensity of timber is bad in the reduction of effective bearing cross-section area caused by burning carbonate and non-carbonized region
Change.And timber parallel-to-grain compressive strength substantially by fiber outside lignin determine, when temperature is up to 100 DEG C, lignin by thermal softening,
Lead to the reduction of timber parallel-to-grain compressive strength, temperature increases then again hard solid.When temperature reaches 300 DEG C or more, Wood carbonization and
Do not have intensity, therefore the Temperature Distribution of middle low-temperature space timber is very big on the influence of its parallel-to-grain compressive strength in glued pin in the scene of a fire.
The foundation of current glue laminated wood member fire protection design mainly have " Code for fire protection design of buildings " (GB 50016-2014) and
"EN 1995-1-2:General-structural fire design".Although EN 1995-1-2 laminated wood fire protection design is advised
The influence of timber varieties of trees density, moisture content to carbonization of wood rate used in glue laminated wood member is considered in model, but is not examined
Consider the influence to thermo parameters method in component；The effective bearing cross-section of the wooden component after the carbonization of wood is only considered in GB50016-2014
Reduce, but consider in low-temperature space strength of wood deterioration.Therefore by glued pin in the fire of this two kinds of standards progress
Fire resistance design has greater difference with the actually active remaining cross-section of pin glued in fire.Although EN 1995-1-2 considers
Influence of the pyrolysis zone to strength of wood, but the zone of action very little.And it is bigger by low-temperature space range in fiery component inside,
So middle low-temperature space timber parallel-to-grain compressive strength deterioration should more be taken seriously.And conventional glue laminated wood member resisting fire design in the world
It is more to be based on full scale test, strength deteriorations all in fire process are equivalent at additional Zero intensity regions.But full size
Model test consuming is larger, there is its distinctive limitation.It is therefore proposed that a kind of simple and effective glued pin fire resistance design
Method is extremely important.
The literature search discovery of the prior art by contrast, there are many fire resistance analysis methods of building structure at present.
These patents are all the fire resistance analysis methods of building structure, and analysis method is relatively cumbersome.And the present invention is then to focus on
In more perspective fire resistance design method, method is simple and effective.These patents compared with the method for the present invention it is different it
Be in:
(1) Chinese invention patent of Publication No. 105512394A, method described in the invention is primarily directed to post and beam
The analysis method of timber structure frame entirety fire resistance.But its analytic process need to utilize the thermal-structure coupled meter of finite element software
It calculates, it is relatively cumbersome.And the present invention focuses on the fire resistance design method of glued pin, by holding for pin glued in fire
Power is carried using the equivalent bearing capacity at pin glued under room temperature of timber high temperature rift grain relative compressive strength multi-ladder simplified model, into
The analysis of row fire resistance.Then glued pin fire resistance is carried out again to design and meet fire protection requirement in 1 hour.The mesh of the two application
Have very big difference.Meanwhile timber high temperature rift grain relative compressive strength multi-ladder simplified model and EN that the invention uses
The strength of wood reduction model of 1995-1-2 has the difference of essence.The multi-ladder simplified model more meets the heated spy of wood lignin
Point, and it is effectively simple.Compared with the present invention, target, process and performance are different.
(2) Chinese invention patent of publication number 104990793A, method described in the invention is primarily directed to wooden after fire
The residual load bearing capacity appraisal procedure of structural construction, what the present invention focused on is true by the fire resistance analysis of pin glued in fire
The fire resistance design of fixed gluing pin.The purpose of the two application is different.Wood in strength of wood and fire after fire simultaneously
Material intensity is also not identical concept.Compared with the present invention, target, process and performance are different.
(3) Chinese invention patent of publication number 103324797A, method described in the invention is mainly Tall Frameworks knot
The check analysis method of structure entirety fire resistance, assessment object is that timber buildings material has this in steel frame, with the present invention
Very big difference.The patent of publication number 103324797A is needed from temperature field to mechanics field analysis structural system, analytic process ten
Divide complexity.And it is the fire resistant design method of simple and effective glued pin that the present invention, which focuses on,.In terms of analogue simulation, finite element
Simulation softward has a material depot to steel, and timber then need it is customized.
Summary of the invention
1, technical problems to be solved by the inivention
For drawbacks described above exists in the prior art, the present invention provides the gluings that low-temperature space strength of wood in consideration deteriorates
Pin fire resistant design method, it is therefore intended that propose a kind of scientific, inexpensive, simple and accurate glued pin resisting fire design side
Method.Consider by pin cross-section temperature distribution glued during fire, in conjunction with the multi-ladder letter of timber high temperature rift grain relative compressive strength
Change model, realizes the glued pin fire protection design method of economic and reliable.The invention can reduce a large amount of full scale specimen tests, reduce
Fire test cost improves research business efficiency and accuracy.
2, technical solution
To achieve the goals above, present invention employs following technical solutions:
The glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration, including following 4 steps:
Step 1: timber pyroconductivity and specific heat thermal property according to specified in EN1995-1-2 establish relevant material
Attribute the case where according to practical fire surface, sets radiation coefficient and Stefan-Boltzmann constant, sets glued pin surface
Heat exchange and surface heat radiation are established Two-Dimensional Heat by finite element analysis software ABAQUS and are passed using standard fire curve curve
Model is passed, determines gluing pin cross-section temperature field distribution；
Step 2: the glued pin cross-section temperature field distribution based on step 1 utilizes wood according to lignin by thermal characteristics
The more broken line deterioration rules of material high temperature rift grain relative compressive strength, it is special according to the variation that wherein low-temperature space intensity is influenced by moisture content
Point, the equivalent rectangular principle of triangle establish timber high temperature rift grain relative compressive strength multi-ladder simplified model.In laminated wood
Several strength degradation regions are divided in column cross-section temperature field distribution, then utilize equivalent area principle, determine gluing pin
The representative section of cross section；The timber high temperature rift grain relative compressive strength multi-ladder simplified model that the present invention uses is expressed as follows:
In formula: fRCIt (T) is the timber rift grain relative compressive strength in temperature T.
Using above-mentioned timber high temperature rift grain relative compressive strength multi-ladder simplified model, then glued pin cross section is equivalent
Section calculation method is as follows:
Aeq=(an+0.8amc+0.7adry+0.4ath)(hn+0.8hmc+0.7hdry+0.4hth)
In formula: anIt is the normal region length of width direction (see marking 8 in Fig. 3)；amcIt is width direction by aqueous
The length that rate influences (see marking 9 in Fig. 3)；adryIt is the dry wooden section length of width direction (see marking 10 in Fig. 3)；athIt is width
It spends direction high temperature pyrolysis section length (see marking 11 in Fig. 3)；hnIt is the normal region length of short transverse (see marking in Fig. 3
12)；hmcIt is the length that short transverse is influenced by moisture content (see marking 13 in Fig. 3)；hdryIt is the dry wooden section length of short transverse
(see marking 14 in Fig. 3)；hthIt is short transverse high temperature pyrolysis section length (see marking 15 in Fig. 3).
Step 3: based on the calculated result in the step 2, determining the residual load bearing capacity by pin glued during fire, root
Load level is held according to the design of glued pin, predicts fire endurance, realizes the glued pin fire resistance analysis during by fire；Glue
It is as follows to close pin residual load bearing capacity calculation formula:
In formula:For stability reduction coefficient of axially loaded compression, Aeq is representative section area, fcFor the room temperature of actually used timber
Parallel-to-grain compressive strength.
Step 4: based on the bearing capacity situation in the step 3, carrying out glued pin fire resistance design.
Glued pin cross-section temperature field distribution in finite element software ABAQUS using Two-Dimensional Heat by being passed in the step 1
Modeling is passed, DC2D4 unit is used.
The finite element Two-Dimensional Heat model of glued pin cross-section temperature field distribution, also needs according to reality in the step 1
The moisture content w of glued pin and tree species density used are determined density and dry density ratio, and radiation coefficient under Service Environment
0.8 and Stefan-Boltzmann constant is taken to take 3.402 × 10-6。
Glued pin is set as coefficient of heat transfer 1500 by the heat exchange of energy meter face in the step 1, and surface emissivity is set as
Emissivity 0.8.
The step 1 Plays fire heating curve chooses standard fire curve curve as defined in international standard ISO834.
In the step 2 several strength degradation regions be normal area (≤30 DEG C), the moisture content zone of influence (30-100 DEG C),
The area Gan Mu (100-200 DEG C) and pyrolysis zone (200-300 DEG C).
The f of glued pin residual load bearing capacity formula in the step 3cThe room temperature rift grain pressure resistance of actually used timber should be taken
Degree.
Detailed description of the invention
Fig. 1 is that glued pin fire resistance design method forms flow chart；
Fig. 2 is glued pin fire resistance analysis flow chart diagram；
Fig. 3 is glued pin cross-section temperature field distribution in the scene of a fire；
1- gluing pin is carbonized line (300 DEG C) by fiery leading edge, 2- charring layer, 3-, 4- pyrolysis zone (200-300
DEG C), the area 5- Gan Mu (100-200 DEG C), the normal area 6- (≤30 DEG C), the 7- moisture content zone of influence (30-100 DEG C), 8- width direction
Normal region length an, 9- is the length a that width direction is influenced by moisture contentmc, the dry wooden section length a of 10- width directiondry, 11-
Width direction high temperature pyrolysis section length ath, the normal region length h of 12- short transversen, 13- short transverse influenced by moisture content
Length hmc, the dry wooden section length h of 14- short transversedry, 15- short transverse high temperature pyrolysis section length hth。
Fig. 4 is timber high temperature rift grain relative compressive strength multi-ladder simplified model figure；
4- pyrolysis zone (200-300 DEG C), the area 5- Gan Mu (100-200 DEG C), the normal area 6- (≤30 DEG C), 7- moisture content shadow
It rings area (30-100 DEG C), 16- timber high temperature rift grain relative compressive strength multi-ladder simplified model, 17- timber high temperature rift grain is opposite
The more broken line degradation models of compression strength.
Fig. 5 is glued pin fire resistance design flow diagram.
Specific implementation method
The following describes the present invention in detail with reference to examples.
Embodiment 1:
Pesudotsuga taxifolia gluing pin, the timber room temperature parallel-to-grain compressive strength of pesudotsuga taxifolia are 33.7MPa, density 450kg/m3, contain
Water rate w is 15%, and laminated wood column dimension is length × width × height: 200mm × 200mm × 4000mm, and it is 20% that load level is held in design,
Four sides is by fire.
The step of being operated according to Fig. 1 and Fig. 2, being designed its fire resistance is as follows:
Step 1: it is 15% according to the practical moisture content w of glued pin, density 450kg/m3, obtained according to EN 1995-1-2
Relevant material properties are established to dry density ratio to timber pyroconductivity and specific heat thermal property and density, see Tables 1 and 2.Root
According to glued pin four sides by the practical by fire behavior condition of fire, sets radiation coefficient 0.8 and Stefan-Boltzmann constant takes 3.402
×10-6.Glued pin is set as coefficient of heat transfer 1500 by the heat exchange of energy meter face, and surface emissivity is set as emissivity 0.8.Using
Standard fire curve curve as defined in international standard ISO834 establishes Two-Dimensional Heat by finite element analysis software ABAQUS and transmits mould
Type obtains pesudotsuga taxifolia gluing pin cross-section temperature field distribution situation using DC2D4 unit.
1 wood thermal conductivity parameter of table
| Temperature (DEG C) | Thermal coefficient (Wm-1K-1) |
| 20 | 0.12 |
| 200 | 0.15 |
| 350 | 0.07 |
| 500 | 0.09 |
| 800 | 0.35 |
| 1200 | 1.50 |
2 Specific Heat of Wood of table and density ratio thermal parameter
| Temperature (DEG C) | Specific heat (kJkg-1K-1) | Timber actual density/timber dry density |
| 20 | 1.53 | 1+w |
| 99 | 1.77 | 1+w |
| 99 | 13.60 | 1+w |
| 120 | 13.50 | 1.00 |
| 120 | 2.12 | 1.00 |
| 200 | 2.00 | 1.00 |
| 250 | 1.62 | 0.93 |
| 300 | 0.71 | 0.76 |
| 350 | 0.85 | 0.52 |
| 400 | 1.00 | 0.38 |
| 600 | 1.40 | 0.28 |
| 800 | 1.65 | 0.26 |
| 1200 | 1.65 | 0 |
Step 2: the pesudotsuga taxifolia gluing pin cross-section temperature field obtained according to ABAQUS finite element analysis software in step 1
Distribution, according to lignin by thermal characteristics, using the more broken line degradation models 17 of timber high temperature rift grain relative compressive strength, according to it
The Variation Features that middle low-temperature space intensity is influenced by moisture content, the equivalent rectangular principle of triangle establish timber high temperature rift grain phase
To compression strength multi-ladder simplified model (such as Fig. 4).In Fig. 4, timber high temperature rift grain relative compressive strength multi-ladder simplifies mould
Type 16, the more broken line degradation models 17 of timber high temperature rift grain relative compressive strength, normal area 6 (regions of temperature≤30 DEG C), moisture content
The zone of influence 7 (region of the temperature at 30-100 DEG C), Gan Muqu 5 (region of the temperature at 100-200 DEG C), 4 (temperature of pyrolysis zone
Region at 200-300 DEG C).Multiple strength degradation regions are divided in pesudotsuga taxifolia gluing pin cross-section temperature field distribution, i.e.,
For several above-mentioned strength degradation regions, as shown in Figure 3.Then equivalent area principle is utilized, determines the equivalent of gluing pin
Section, shown in the calculation formula of the representative section of following gluing pin.In Fig. 3, glued pin is by fiery leading edge 1, charring layer 2
(regions of temperature > 300 DEG C) carbonize line 3 (300 DEG C), pyrolysis zone 4 (region of the temperature at 200-300 DEG C), Gan Muqu 5
(region of the temperature at 100-200 DEG C), normal area 6 (regions of temperature≤30 DEG C), (temperature is at 30-100 DEG C for the moisture content zone of influence 7
Region), anFor the normal region length (see marking 8 in figure) of width direction, amcThe length influenced for width direction by moisture content
It spends (see marking 9 in figure), adryFor the dry wooden section length (see marking 10 in figure) of width direction, athIt is width direction high temperature pyrolysis
Section length (see marking 11 in figure), hnFor the normal region length (see marking 12 in figure) of short transverse, hmcFor short transverse by
The length (see marking 13 in figure) that moisture content influences, hdryFor the dry wooden section length (see marking 14 in figure) of short transverse, hthFor height
Direction high temperature pyrolysis section length (see marking 15 in figure).The timber high temperature rift grain relative compressive strength multi-ladder letter that the present invention uses
It is as follows to change model tormulation:
In formula: fRCIt (T) is the timber rift grain relative compressive strength in temperature T.
Using above-mentioned timber high temperature rift grain relative compressive strength multi-ladder simplified model, then the representative section of glued pin
Calculation formula is as follows:
Aeq=(an+0.8amc+0.7adry+0.4ath)(hn+0.8hmc+0.7hdry+0.4hth)
In formula: anIt is the normal region length of width direction (see marking 8 in Fig. 3)；amcIt is width direction by aqueous
The length that rate influences (see marking 9 in Fig. 3)；adryIt is the dry wooden section length of width direction (see marking 10 in Fig. 3)；athIt is width
It spends direction high temperature pyrolysis section length (see marking 11 in Fig. 3)；hnIt is the normal region length of short transverse (see marking in Fig. 3
12)；hmcIt is the length that short transverse is influenced by moisture content (see marking 13 in Fig. 3)；hdryIt is the dry wooden section length of short transverse
(see marking 14 in Fig. 3)；hthIt is short transverse high temperature pyrolysis section length (see marking 15 in Fig. 3).
According to the gluing pin cross-section temperature field pattern, as shown in Figure 3.In fire duration 42min, anFor width
The length (i.e. the length of width direction temperature≤30 DEG C) of the normal region in direction, an=60mm.Similarly amcFor width direction water
The length (i.e. length of the width direction temperature in 30-100 DEG C of section) of part zone of influence, amc=56mm.adryIt is dry for width direction
The length (i.e. length of the width direction temperature in 100-200 DEG C of section) in the wooden area, adry=8mm.athFor width direction moisture content shadow
Ring the length (i.e. length of the width direction temperature in 30-100 DEG C of section) in area, athc=6mm.Due to the embodiment laminated wood
Column cross sectional dimensions is square, so an=bn,amc=bmc,adry=bdryAnd ath=bth..It is worth noting that bnFor length
The normal region length in direction, bmcFor the length that length direction is influenced by moisture content, bdryFor the dry wooden section length of length direction, bth
For length direction high temperature pyrolysis section length, in fire duration 42min, Aeq=(60+56 × 0.8+8 × 0.7+6 × 0.4)2=
112.82=1.27 × 104cm2。
Step 3: according to the glued pin representative section in acquired fire process, substituting into following glued pin residue and hold
It carries in power formula:
In formula:For stability reduction coefficient of axially loaded compression, AeqFor representative section area, fcFor the room temperature of actually used timber
Parallel-to-grain compressive strength.
The checking computations of room temperature bearing capacity calculation result,It is 1.27 × 10 for 0.84, Aeq4cm2, fcFor 33.7MPa, then calculates and hold
Load power is N=0.84 × 33.7 × 2002=1135 (KN), test destructive power are 1190 (KN), calculate intensity and proof strength phase
When approaching, illustrate that room temperature timber parallel-to-grain compressive strength and Bearing Capacity Formula meet the requirements.Glued pin 40min in fire test
When destroy, at this time calculate bearing capacity be N (40min)=33.7 × 0.63 × 112.82=270 (KN).And it actually holds lotus intensity and is
240 (KN), it is as a result fairly close.Illustrate that the invention has accurate fire resistance analysis ability, and compares EN1995-1-
2 calculated result is more accurate.
Step 4: experiments have shown that holding lotus 20%, 40min can only be maintained in a fire, it is consistent with the invention calculated result.
Glued pin fire resistance design cycle according to Fig.5, to meet 1 hour fire-resistance principle, should suitably reduce military service load or
Increase column section.220mm × 220mm is changed to using laminated wood column cross-section size, it is same as above to calculate, when by fiery 60min, Aeq
=(50+66 × 0.8+8 × 0.7+6 × 0.4)2=110.82=1.23 × 104cm2, calculating bearing capacity N (60min)=0.62 ×
33.7×110.82=257 (KN), it is close with lotus intensity 240 (KN) is held.When laminated wood column cross-section size is 220mm × 220mm
Meet fire protection design requirement in 1 hour.This method is effective and feasible glued pin fire resistance design method.
Embodiment 2:
Larch gluing pin, larchen parallel-to-grain compressive strength are 61.3MPa, density 591kg/m3, moisture content w is
11.0%, laminated wood column dimension is length × width × height: 200mm × 200mm × 4000mm, and it is 65% that load level is held in design, four sides
By fire.
Analysis personnel operating procedure is such as embodiment 1:
Step 1: it is 11.0% according to the practical moisture content w of glued pin, density 591kg/m3.According to EN 1995-1-
2, which obtain timber pyroconductivity and specific heat thermal property and density, establishes relevant material properties to dry density ratio, sees Tables 1 and 2.
According to glued pin four sides by the practical by fire behavior condition of fire, sets radiation coefficient 0.8 and Stefan-Boltzmann constant takes
3.402×10-6.Glued pin is set as coefficient of heat transfer 1500 by the heat exchange of energy meter face, and surface emissivity is set as emissivity
0.8.It adopts international standards standard fire curve curve as defined in ISO834, passes through finite element analysis software ABAQUS and establish two dimension
Heat transfer model obtains larch gluing pin cross-section temperature field distribution situation using DC2D4 unit.
Step 2: the larch gluing pin cross-section temperature field obtained according to ABAQUS finite element analysis software in step 1
Distribution.According to lignin by thermal characteristics, using the more broken line degradation models 17 of timber high temperature rift grain relative compressive strength, according to it
The Variation Features that middle low-temperature space intensity is influenced by moisture content, the equivalent rectangular principle of triangle establish timber high temperature rift grain phase
To compression strength multi-ladder simplified model (such as Fig. 4).In Fig. 4, timber high temperature rift grain relative compressive strength multi-ladder simplifies mould
Type 16, the more broken line degradation models 17 of timber high temperature rift grain relative compressive strength, normal area 6 (regions of temperature≤30 DEG C), moisture content
The zone of influence 7 (region of the temperature at 30-100 DEG C), Gan Muqu 5 (region of the temperature at 100-200 DEG C), 4 (temperature of pyrolysis zone
Region at 200-300 DEG C).Multiple strength degradation regions are divided in pesudotsuga taxifolia gluing pin cross-section temperature field distribution, i.e.,
For several above-mentioned strength degradation regions, as shown in Figure 3.Then equivalent area principle is utilized, determines the equivalent of gluing pin
Section, shown in the calculation formula of the representative section of following gluing pin.In Fig. 3, glued pin is by fiery leading edge 1, charring layer 2
(regions of temperature > 300 DEG C) carbonize line 3 (300 DEG C), pyrolysis zone 4 (region of the temperature at 200-300 DEG C), Gan Muqu 5
(region of the temperature at 100-200 DEG C), normal area 6 (regions of temperature≤30 DEG C), (temperature is at 30-100 DEG C for the moisture content zone of influence 7
Region), anFor the normal region length (see marking 8 in figure) of width direction, amcThe length influenced for width direction by moisture content
It spends (see marking 9 in figure), adryFor the dry wooden section length (see marking 10 in figure) of width direction, athIt is width direction high temperature pyrolysis
Section length (see marking 11 in figure), hnFor the normal region length (see marking 12 in figure) of short transverse, hmcFor short transverse by
The length (see marking 13 in figure) that moisture content influences, hdryFor the dry wooden section length (see marking 14 in figure) of short transverse, hthFor height
Direction high temperature pyrolysis section length (see marking 15 in figure).The timber high temperature rift grain relative compressive strength multi-ladder letter that the present invention uses
It is as follows to change model tormulation:
In formula: fRCIt (T) is the timber rift grain relative compressive strength in temperature T.
Using above-mentioned timber high temperature rift grain relative compressive strength multi-ladder simplified model, then the representative section of glued pin
Calculation formula is as follows:
Aeq=(an+0.8amc+0.7adry+0.4ath)(hn+0.8hmc+0.7hdry+0.4hth)
In formula: anIt is the normal region length of width direction (see marking 8 in Fig. 3)；amcIt is width direction by aqueous
The length that rate influences (see marking 9 in Fig. 3)；adryIt is the dry wooden section length of width direction (see marking 10 in Fig. 3)；athIt is width
It spends direction high temperature pyrolysis section length (see marking 11 in Fig. 3)；hnIt is the normal region length of short transverse (see marking in Fig. 3
12)；hmcIt is the length that short transverse is influenced by moisture content (see marking 13 in Fig. 3)；hdryIt is the dry wooden section length of short transverse
(see marking 14 in Fig. 3)；hthIt is short transverse high temperature pyrolysis section length (see marking 15 in Fig. 3).
According to the gluing pin cross-section temperature field pattern, as shown in Figure 3.In fire duration 30min, anTake width
The length (i.e. the length of width direction temperature≤30 DEG C) of the normal region in direction, an=80mm.Similarly amcTake width direction water
The length (i.e. length of the width direction temperature in 30-100 DEG C of section) of part zone of influence, amc=58mm.adryTake width direction dry
The length (i.e. length of the width direction temperature in 100-200 DEG C of section) in the wooden area, adry=8mm.athTake width direction moisture content shadow
Ring the length (i.e. length of the width direction temperature in 30-100 DEG C of section) in area, athc=4mm.Due to the embodiment laminated wood
Column cross sectional dimensions is square, so an=bn,amc=bmc,adry=bdryAnd ath=bth..Then in fire duration 30min,
Aeq=(80+58 × 0.8+8 × 0.7+4 × 0.4)2=133.62=1.78 × 104cm2。
Step 3: according to the glued pin representative section in acquired fire process, substituting into following glued pin residue and hold
It carries in power formula:
In formula:For stability reduction coefficient of axially loaded compression, AeqFor representative section area, fcFor the room temperature of actually used timber
Parallel-to-grain compressive strength.
Glued pin destroys when 30min in fire test,It is 0.704, AeqIt is 1.78 × 104cm2, fcFor
61.3MPa, then calculating bearing capacity at this time is N (30min)=61.3 × 0.704 × 133.62=770 (KN).And it is strong actually to hold lotus
Degree is 780 (KN), as a result fairly close, illustrates that the invention has accurate fire resistance analysis ability.
Step 4: experiments have shown that holding lotus 65%, 30min can only be maintained in a fire, it is consistent with the invention calculated result.
Glued pin fire resistance design cycle according to Fig.5, to meet 1 hour fire-resistance principle, should suitably reduce military service load or
Increase column section.220mm × 220mm is changed to using laminated wood column cross-section size, it is same as above to calculate, when by fiery 60min, Aeq
=(40+74 × 0.8+10 × 0.7+4 × 0.4)2=1082=1.16 × 104cm2, calculating bearing capacity N (60min)=0.61 ×
61.3×1082=404 (KN) differ larger with lotus intensity 780 (KN) is held.Using laminated wood column cross-section size be changed to 240mm ×
240mm, it is same as above to calculate, when by fiery 60min, Aeq=(60+76 × 0.8+6 × 0.7+4 × 0.4)2=126.62=1.6
×104cm2, calculate bearing capacity N (60min)=0.68 × 61.3 × 126.62=668 (KN) are differed with lotus intensity 780 (KN) is held
It is larger.250mm × 250mm is changed to using laminated wood column cross-section size, it is same as above to calculate, when by fiery 60min, Aeq=(70+
76×0.8+6×0.7+4×0.4)2=136.62=1.87 × 104cm2, calculate bearing capacity N (60min)=0.713 × 61.3
×136.62=816 (KN), with hold lotus intensity 780 (KN) very close to.When then laminated wood column cross-section size is 250mm × 250mm
Meet fire protection design requirement in 1 hour.This method is effective and feasible glued pin fire resistance design method.
Claims (8)
1. the glued pin fire resistant design method of low-temperature space strength of wood deterioration in considering, which comprises the following steps:
(1) glued pin cross-section temperature field distribution is determined by finite element analysis software；
(2) the glued pin cross-section temperature field distribution based on step (1) establishes timber according to wood lignin by thermal characteristics
High temperature rift grain relative compressive strength multi-ladder simplified model determines the representative section of gluing pin cross section；What the present invention used
Timber high temperature rift grain relative compressive strength multi-ladder simplified model is expressed as follows:
In formula: fRCIt (T) is the timber rift grain relative compressive strength in temperature T；
According to above-mentioned timber high temperature rift grain relative compressive strength multi-ladder simplified model, the representative section meter of glued pin cross section
Calculation method is as follows:
Aeq=(an+0.8amc+0.7adry+0.4ath)(hn+0.8hmc+0.7hdry+0.4hth)
In formula: anFor the normal region length of width direction；amcThe length influenced for width direction by moisture content；adryFor width
The dry wooden section length in direction；athFor width direction high temperature pyrolysis section length；hnFor the normal region length of short transverse；hmcFor height
The length that direction is influenced by moisture content；hdryFor the dry wooden section length of short transverse；hthFor short transverse high temperature pyrolysis section length；
(3) it based on the representative section calculated result in the step (2), determines and is carried by the remaining of pin glued during fire
Power holds load level according to the design of glued pin, predicts fire endurance, realizes the glued pin fire resistance point during by fire
Analysis；Glued pin residual load bearing capacity calculation formula is as follows:
In formula:For stability reduction coefficient of axially loaded compression, AeqFor representative section area, fcFor the room temperature rift grain of actually used timber
Compression strength；
(4) based on the glued pin residual load bearing capacity in the step (3), glued pin fire resistance design is carried out.
2. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 1, special
Sign is: in the step (1), the finite element analysis software determines glued pin cross-section temperature field distribution, with specific reference to
The case where timber pyroconductivity, specific heat establish material properties, fire surface practical according to glued pin, setting radiation coefficient and
Stefan-Boltzmann constant sets glued pin surface heat exchange and surface heat radiation, using standard fire curve curve,
It is determined by carrying out glued pin cross section Two-Dimensional Heat transmitting modeling in finite element analysis software ABAQUS using DC2D4 unit
Glued pin cross-section temperature field distribution.
3. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 2, special
Sign is: the Two-Dimensional Heat transmitting modeling of the gluing pin cross section should be according to the moisture content of pin glued under practical Service Environment
The density of w and tree species used.
4. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 2, special
Sign is: the radiation coefficient takes 0.8, Stefan-Boltzmann constant to take 3.402 × 10-6。
5. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 2, special
Sign is: the gluing pin surface heat exchange is set as coefficient of heat transfer 1500, and surface heat radiation is set as emissivity 0.8.
6. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 2, special
Sign is: the standard fire curve curve chooses standard fire curve curve as defined in international standard ISO834.
7. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 1, special
Sign is: the glued pin cross-section temperature field distribution of step (1) is based in the step (2), according to the heated spy of lignin
Property, timber high temperature rift grain relative compressive strength multi-ladder simplified model is established, determines the representative section of gluing pin cross section, tool
Body is to deteriorate rule using the more broken lines of timber high temperature rift grain relative compressive strength, is influenced according to wherein low-temperature space intensity by moisture content
Variation Features, the equivalent rectangular principle of triangle establishes timber rift grain relative compressive strength multi-ladder simplified model；In glue
It closes in the field distribution of pin cross-section temperature and divides several strength degradation regions, then utilize equivalent area principle, determine glued
The representative section of pin cross section.
8. the glued pin fire resistant design method that low-temperature space strength of wood deteriorates in consideration according to claim 7, special
Sign is: several described strength degradation regions are normal area, the moisture content zone of influence, the area Gan Mu and pyrolysis zone.
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Application publication date: 20170322 Assignee: NANJING GONGDA WOOD STRUCTURE TECHNOLOGY CO.,LTD. Assignor: NANJING University OF TECHNOLOGY Contract record no.: X2023320000246 Denomination of invention: A Fire resistant Design Method for Glued Wood Columns Considering the Deterioration of Wood Strength in Medium and Low Temperature Regions Granted publication date: 20191122 License type: Common License Record date: 20231206 |
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