Membrane structure fire hazard temperature field simulation method considering membrane material weld joint disengagement

Abstract

The invention discloses a membrane structure fire hazard temperature field simulation method considering membrane material weld joint disengagement. The method comprises the following steps: S1, constructing a three-dimensional model of a membrane structure building to be simulated; s2, the three-dimensional model is imported into Pyros im software; s3, grids are divided in Pyros im software according to the fire source power of the membrane structure building to be simulated, the width of a membrane material welding seam and the distribution position of the membrane material welding seam, and the three-dimensional model is converted into an obstacle; s4, fire source parameters of the membrane structure building to be simulated and material attributes and geometric attributes of building components are set in Pyros im software; s5, temperature measuring points are arranged in Pyros im software, and an FDS program is called for calculation; and S6, contrastively analyzing and considering the influence of membrane material weld joint separation on the fire temperature field of the membrane structure building. According to the invention, the phenomenon that smoke escapes due to the fact that the membrane material is disengaged at the weld joint when a fire occurs in the membrane building structure can be simulated, so that the fire temperature field of the membrane building structure considering the disengagement of the membrane material weld joint is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of fire resistance of building structures, and more particularly to a method for simulating the temperature field of a membrane structure fire taking into account the detachment of a membrane material weld. Background Art

[0002] Skeleton membrane structures are widely used in sports buildings, residential buildings, exhibition buildings, etc. Skeleton membrane structures generally use steel structures as skeletons and membrane materials as enclosure structures. However, the strength of steel is greatly affected by temperature. When the temperature is higher than 400°C, the strength and elastic modulus of steel begin to drop sharply. When the temperature reaches 650°C, the steel basically loses its strength. Therefore, when a fire occurs, the skeleton membrane structure may become unstable due to the failure of the strength of the steel structure.

[0003] The weld of the membrane material is a weak point of the membrane structure. The membrane surface at the weld of PVC and PTFE membrane materials will crack and fail when the temperature reaches about 200℃ and 300℃ respectively. By utilizing this characteristic of the membrane material, when a fire breaks out indoors, the heat and smoke generated by the combustion gather upwards, the temperature of the membrane surface rises, the weld cracks, and smoke exhaust holes are formed, which can effectively prevent indoor objects and steel frames from being continuously exposed to high temperature environments; secondly, it limits the accumulation of smoke in the use area, which can provide better visibility indoors, facilitate personnel evacuation and firefighting by firefighters. Therefore, considering the characteristic of the membrane material weld disengaging at high temperatures, the steel structure temperature of the skeleton membrane structure can be effectively reduced, which is effective for the stability of the skeleton membrane structure under fire.

[0004] This method can simulate the phenomenon that the membrane material detaches at the weld of the membrane structure during a fire, causing smoke to escape, and solves the key technical problem of how to obtain the fire temperature field of the membrane structure taking into account the detachment of the membrane material weld. Summary of the invention

[0005] In view of this, the present invention provides a method for simulating the temperature field of a membrane structure fire taking into account the detachment of a membrane material weld, aiming to solve the above technical problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for simulating the temperature field of a membrane structure fire considering the separation of a membrane material weld comprises the following steps:

[0008] S1. construct a three-dimensional model of the membrane structure building to be simulated;

[0009] S2, import the three-dimensional model into Pyrosim software;

[0010] S3. In the Pyrosim software, the grid is divided according to the fire source power of the membrane structure building to be simulated, the width of the membrane material weld and the distribution position of the membrane material weld, and the three-dimensional model is converted into obstacles;

[0011] S4. Setting the fire source parameters of the membrane structure building to be simulated and the material properties and geometric properties of the building components in the Pyrosim software;

[0012] S5. Arrange temperature measurement points in Pyrosim software and call FDS program for calculation;

[0013] S6. Comparative analysis considers the impact of membrane material weld detachment on the fire temperature field of membrane structure buildings.

[0014] The beneficial effect of the above technical solution is that it can simulate the phenomenon that the membrane material of the membrane building structure is detached at the weld when a fire occurs, causing smoke to escape, and solve the key technical problem of how to obtain the fire temperature field of the membrane building structure taking into account the detachment of the membrane material weld.

[0015] Preferably, step S1 includes:

[0016] S11. Establish detailed information of the membrane structure building to be simulated, including the use function, geometric parameters, physical parameters of building materials, heat release rate of membrane materials, ventilation conditions, presence or absence of fire sprinkler system, type of combustibles and distribution location of combustibles. Physical parameters of building materials include density, specific heat capacity and thermal conductivity.

[0017] S12, establishing fire source parameters according to the use function of the membrane structure building to be simulated in step S11, the presence or absence of a fire sprinkler system, the type of combustibles, and the distribution location of the combustibles, the fire source parameters including fire source power, fire model, and fire source location;

[0018] S13. Construct a three-dimensional model according to the geometric parameters of the membrane structure building to be simulated established in step S11.

[0019] Preferably, the three-dimensional model is drawn using three-dimensional modeling software.

[0020] Preferably, the three-dimensional model is drawn using Rhino, Sketchup or Revit.

[0021] Preferably, in step S2, the three-dimensional model constructed in step S13 is imported into Pyrosim software.

[0022] Preferably, step S3 comprises:

[0023] S31, in the Pyrosim software, determining the grid size according to the fire source power of the membrane structure building to be simulated and the width of the membrane material weld, and dividing the grid according to the width of the membrane material weld and the distribution position of the membrane material weld;

[0024] S32. Select the "Convert to blocks" command in the Pyrosim software to convert the imported 3D model into obstacles, and check "Allow thin obstruction" to make the thickness of the obstacles 0.

[0025] Preferably, step S4 comprises:

[0026] S41, according to the fire source parameters established in step S12, the fire source heat release rate per unit area and the fire source growth curve are set by defining a Burner type surface; a vent is established and given a Burner surface attribute, the vent is used as a fire source, and the area of ​​the vent is the fire source area; the product of the fire source area and the fire source heat release rate per unit area is the fire source power;

[0027] S42. According to the physical parameters of the building materials established in step S11, different material models are established in the Materials tab; different types of surfaces are established based on different material models, that is, the material types and corresponding thicknesses of the membrane surface, membrane material welds and other components are specified under the Material Layers tab in the Surface tab; the surface setting of the membrane material welds needs to specify the heat release rate per unit area and the weld detachment temperature in the "Reaction" tab, and "Allow obstruction to burn away" is checked to simulate the phenomenon of the membrane material weld detaching at high temperature;

[0028] S43, assigning the surface properties of the membrane surface, the membrane material weld and other components to the membrane surface, the membrane material weld and other components respectively.

[0029] Preferably, step S5 includes:

[0030] S51. Use thermocouples to arrange temperature measurement points in Pyrosim software and set simulation parameters, including air supply vents, smoke exhaust vents, and sprinklers;

[0031] S52, setting the ambient temperature, simulation duration and output parameters, and calling the FDS program for calculation.

[0032] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a method for simulating the fire temperature field of a membrane structure taking into account the detachment of membrane material welds, which solves the key technical problem of how to obtain the fire temperature field of a membrane building structure taking into account the detachment of membrane material welds. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 A flow chart of a membrane structure fire temperature field simulation method considering membrane material weld detachment provided by the present invention;

[0035] Figure 2 A schematic diagram of a membrane structure building model in an example provided by the present invention;

[0036] Figure 3 The curve of the temperature just above the fire source near the membrane surface with or without weld detachment versus time;

[0037] Figure 4 It is a temperature cloud diagram showing whether the weld is detached near the membrane surface.

[0038] in,

[0039] 1-Roof covered with PVC membrane; 2-Fence; 3-Air supply vent. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] See attached Figure 1 The embodiment of the present invention discloses a method for simulating the temperature field of a membrane structure fire considering the separation of a membrane material weld, comprising the following steps:

[0042] S1. construct a three-dimensional model of the membrane structure building to be simulated;

[0043] S2, import the three-dimensional model into Pyros im software;

[0044] S3, in the Pyros im software, divide the grid according to the fire source power of the membrane structure building to be simulated, the width of the membrane material weld and the distribution position of the membrane material weld, and convert the three-dimensional model into obstacles;

[0045] S4. Setting the fire source parameters of the membrane structure building to be simulated and the material properties and geometric properties of the building components in the Pyros im software;

[0046] S5. Arrange temperature measurement points in Pyros im software and call FDS program for calculation;

[0047] S6. Comparative analysis considers the impact of membrane material weld detachment on the fire temperature field of membrane structure buildings.

[0048] In this embodiment, step S1 includes:

[0049] S11. Establish detailed information of the membrane structure building to be simulated, including the use function, geometric parameters, physical parameters of building materials, heat release rate of membrane materials, ventilation conditions, presence or absence of fire sprinkler system, type of combustibles and distribution location of combustibles. Physical parameters of building materials include density, specific heat capacity and thermal conductivity.

[0050] S12, establishing fire source parameters according to the use function of the membrane structure building to be simulated in step S11, the presence or absence of a fire sprinkler system, the type of combustibles, and the distribution location of the combustibles, the fire source parameters including fire source power, fire model, and fire source location;

[0051] S13. Construct a three-dimensional model according to the geometric parameters of the membrane structure building to be simulated established in step S11.

[0052] The three-dimensional model is drawn using three-dimensional modeling software; the three-dimensional model in this application can be drawn using Rhino, Sketchup or Revit.

[0053] Attached Figure 2 A three-dimensional model of a membrane building structure is established using Rhino software, the three-dimensional model includes a roof 1 covered with PVC membrane material, a fence 2 and air inlets 3, the fence 2 defines a rectangular area, the upper end of the fence 2 is provided with a roof 1 covered with PVC membrane material, the upper end of the area enclosed by the fence 2 is blocked by the roof 1 covered with PVC membrane material, and four relatively arranged air inlets 3 are opened on the fence 2; the fence 2 is assumed to be an insulating surface during simulation, the air inlet 3 is a rectangular opening and its size is 4×2m, the membrane building structure has no smoke exhaust outlets, sprinklers and other fire-fighting facilities, the combustible is set to be plastic foam, the combustible is located in the area enclosed by the fence 2 and is arranged in the center, and the fire source is 0m above the ground.

[0054] In this embodiment, the membrane structure building to be simulated is used as a store without a fire sprinkler system. According to Table 4.6.7 of the Technical Standard for Smoke and Exhaust Systems in Buildings (GB51251-2017), the fire source power Q is determined to be 10MW. According to Table 14 of the Technical Code for Fire Protection of Steel Structures in Buildings (CECS200:2006), the heat release rate per unit area of ​​the store is q e =500kW / m 2 , then the fire source area A is Q / q e =20m2 According to the Technical Standard for Smoke Control and Exhaust Systems in Buildings (GB51251-2017), the fire growth model shown in formula (1) is used. The combustible material is plastic foam, the fire type is rapid fire, and α = 0.044 kW / s 2 .

[0055] Q=α·t 2 (1)

[0056] Where: Q is the fire source power (kW); α is the fire growth coefficient (kW / s 2 );t is time (s).

[0057] Step S2: Import the three-dimensional model of the membrane structure building generated in step S13 into the Pyros im software.

[0058] Step S3 includes:

[0059] S31, in the Pyrosim software, determining the grid size according to the fire source power of the membrane structure building to be simulated and the width of the membrane material weld, and dividing the grid according to the width of the membrane material weld and the distribution position of the membrane material weld;

[0060] The grid size δ and the characteristic diameter of the fire source D* generally meet the requirement of D* / δ∈[4,16], where D* is calculated according to formula (2):

[0061]

[0062] Where: Q is the fire source power (kW); ρ ∞ is the initial value of ambient air density, which is 1.2 kg / m 3 ;c ∞ is the initial value of specific heat capacity, which is 1 kJ / (kg·K); T ∞ is the initial value of the ambient temperature, which is 293K; g is the acceleration due to gravity, which is 9.81m / s 2 .

[0063] In addition, in order to accurately simulate the phenomenon of membrane material weld detachment, the grid size at the membrane material weld should be at least consistent with the membrane material weld width.

[0064] S32. Select the "Convert to blocks" command in the Pyrosim software to convert the imported 3D model into obstacles, and check "Allow thin obstruction" to make the thickness of the obstacles 0.

[0065] Step S4 includes:

[0066] S41, according to the fire source parameters established in step S12, the fire source heat release rate per unit area and the fire source growth curve are set by defining a Burner type surface; a vent is established and given a Burner surface attribute, the vent is used as a fire source, and the area of ​​the vent is the fire source area; the product of the fire source area and the fire source heat release rate per unit area is the fire source power;

[0067] S42. According to the physical parameters of the building materials established in step S11, different material models are established in the Materials tab; different types of surfaces are established based on different material models, that is, the material types and corresponding thicknesses of the membrane surface, membrane material welds and other components are specified under the Material Layers tab in the Surface tab; the surface setting of the membrane material welds needs to specify the heat release rate per unit area and the weld detachment temperature in the "Reaction" tab, and "Allow obstruction to burn away" is checked to simulate the phenomenon of the membrane material weld detaching at high temperature;

[0068] S43, assigning the surface properties of the membrane surface, the membrane material weld and other components to the membrane surface, the membrane material weld and other components respectively.

[0069] Step S5 includes:

[0070] S51. Arrange temperature measurement points using thermocouples and set simulation parameters, including air supply ports, smoke exhaust ports, sprinklers, etc.;

[0071] S52, set the ambient temperature, simulation duration and output parameters, and call the FDS program for calculation.

[0072] For the convenience of comparison, the influence of the detachment of the membrane weld on the internal smoke temperature field was considered. A temperature measuring point was arranged at the membrane surface directly above the fire source. At the same time, a measuring point was arranged every 1.25m along the membrane surface to draw a temperature cloud map near the membrane surface. The calculation time was set to 1800s.

[0073] Step S6: Comparative analysis is performed to consider the impact of membrane material weld detachment on the membrane structure fire temperature field.

[0074] In order to compare the effect of the membrane material weld detachment on the internal smoke temperature field, a control example is set up, that is, the membrane structure building temperature field example without considering the weld detachment. The final results are shown in the attached figure. Figure 3 , 4 shown.

[0075] See attached Figure 3, is the curve of the temperature above the fire source near the membrane surface with or without weld detachment over time, where the solid line and dotted line represent the temperature above the fire source near the membrane surface in the two cases of no weld detachment and weld detachment, respectively. It can be seen that the temperature above the fire source near the membrane surface when considering weld detachment is lower than that when not considering weld detachment.

[0076] See attached Figure 4 , is the temperature cloud diagram near the membrane surface with or without weld detachment, where Figure 4 (a) and (b) are the temperature cloud diagrams near the membrane surface at t = 300s and t = 1800s respectively when the weld is not detached. Figure 4 (c) and (d) are the temperature cloud diagrams near the membrane surface at t = 300s and t = 1800s respectively when the weld is detached. Figure 4 (a) and (c) show that in the early stage of fire development, when the temperature at the membrane weld has not reached the weld detachment temperature, the temperature distribution near the membrane surface is not much different with or without weld detachment; Figure 4 (b) and (d) show that when the fire development is in a stable stage, after the temperature at the weld reaches the weld disengagement temperature, the weld disengages to varying degrees, and hot smoke overflows along the formed holes. Therefore, the temperature value near the membrane surface when considering weld disengagement is significantly lower than the temperature value when not considering weld disengagement.

[0077] The membrane structure fire temperature field simulation method considering the membrane material weld detachment provided by the present invention solves the key technical problem of how to obtain the membrane structure fire temperature field considering the membrane material weld detachment.

[0078] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0079] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simulating the temperature field of a membrane structure fire considering the separation of membrane welds, characterized in that: The following steps are involved: S1. construct a three-dimensional model of the membrane structure building to be simulated; S2, import the three-dimensional model into Pyrosim software; S3. In the Pyrosim software, the grid is divided according to the fire source power of the membrane structure building to be simulated, the width of the membrane material weld and the distribution position of the membrane material weld, and the three-dimensional model is converted into obstacles; S4. Setting the fire source parameters of the membrane structure building to be simulated and the material properties and geometric properties of the building components in the Pyrosim software; S5. Arrange temperature measurement points in Pyrosim software and call FDS program for calculation; S6. Comparative analysis considers the impact of membrane material weld detachment on the fire temperature field of membrane structure buildings.

2. A membrane structure fire temperature field simulation method considering membrane material weld detachment according to claim 1, characterized in that: Step S1 includes: S11. Establish detailed information of the membrane structure building to be simulated, including the use function, geometric parameters, physical parameters of building materials, heat release rate of membrane materials, ventilation conditions, presence or absence of fire sprinkler system, type of combustibles and distribution location of combustibles. Physical parameters of building materials include density, specific heat capacity and thermal conductivity. S12, establishing fire source parameters according to the use function of the membrane structure building to be simulated in step S11, the presence or absence of a fire sprinkler system, the type of combustibles, and the distribution location of the combustibles, the fire source parameters including fire source power, fire model, and fire source location; S13. Construct a three-dimensional model according to the geometric parameters of the membrane structure building to be simulated established in step S11.

3. The method for simulating the temperature field of a membrane structure fire considering the separation of the membrane weld according to claim 2 is characterized in that: The three-dimensional model is drawn using three-dimensional modeling software.

4. The method for simulating the temperature field of a membrane structure fire considering the separation of the membrane weld according to claim 3 is characterized in that: The 3D model is drawn using Rhino, Sketchup or Revit.

5. The method for simulating the temperature field of a membrane structure fire considering the separation of the membrane weld according to claim 2, characterized in that: In step S2, the three-dimensional model constructed in step S13 is imported into the Pyrosim software.

6. The method for simulating the temperature field of a membrane structure fire considering the separation of the membrane material weld according to claim 5, characterized in that: Step S3 includes: S31, in the Pyrosim software, determining the grid size according to the fire source power of the membrane structure building to be simulated and the width of the membrane material weld, and dividing the grid according to the width of the membrane material weld and the distribution position of the membrane material weld; S32. Select the "Convert to blocks" command in the Pyrosim software to convert the imported 3D model into obstacles, and check "Allow thin obstruction" to make the thickness of the obstacles 0.

7. The method for simulating the temperature field of a membrane structure fire considering the separation of the membrane weld according to claim 6, characterized in that: Step S4 includes: S41, according to the fire source parameters established in step S12, the fire source heat release rate per unit area and the fire source growth curve are set by defining a Burner type surface; a vent is established and given a Burner surface attribute, the vent is used as a fire source, and the area of ​​the vent is the fire source area; the product of the fire source area and the fire source heat release rate per unit area is the fire source power; S42. According to the physical parameters of the building materials established in step S11, different material models are established in the Materials tab; different types of surfaces are established based on different material models, that is, the material types and corresponding thicknesses of the membrane surface, membrane material welds and other components are specified under the Material Layers tab in the Surface tab; the surface setting of the membrane material welds needs to specify the heat release rate per unit area and the weld detachment temperature in the "Reaction" tab, and "Allow obstruction to burn away" is checked to simulate the phenomenon of the membrane material weld detaching at high temperature; S43, assigning the surface properties of the membrane surface, the membrane material weld and other components to the membrane surface, the membrane material weld and other components respectively.

8. The method for simulating the temperature field of a membrane structure fire taking into account the separation of the membrane material weld according to claim 5, characterized in that: Step S5 includes: S51. Use thermocouples to arrange temperature measurement points in Pyrosim software and set simulation parameters, including air supply vents, smoke exhaust vents and sprinklers; S52, setting the ambient temperature, simulation duration and output parameters, and calling the FDS program for calculation.

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