Fireproof design method for mechanical three-dimensional parking garage

Abstract

The invention relates to the technical field of parking garages, and discloses a fireproof design method for a mechanical three-dimensional parking garage, which is suitable for urban high-density parking areas containing new energy vehicles. The method comprises the following core steps: determining a first-grade fire resistance grade, and constructing a specific fire heating curve containing thermal runaway, continuous combustion and attenuation stages in combination with a new energy vehicle spontaneous combustion experiment and FDS simulation; the critical temperature method is used for calculating the temperature rise of the component, and the bearing force method is used for introducing local high-temperature correction; hierarchical fireproof protection (steel structure multi-layer coating, equipment partition isolation and active fireproof linkage) is designed; and strengthening a fireproof structure and making a full-period maintenance plan. The method breaks through the limitation of the traditional design, covers the checking calculation of key components, greatly improves the structural safety and system reliability in the fire, and is high in operability and wide in adaptability.

Description

Technical Field

[0001] This invention relates to the field of parking garage technology, specifically a fireproof design method for a mechanical automated parking garage. Background Technology

[0002] With the continuous increase in the number of motor vehicles in cities, parking difficulties have become one of the challenges in urban management. Mechanical automated parking garages are widely used due to their efficient use of land resources. However, due to the large number of vehicles parked in these garages, the consequences of a fire would be unimaginable. The widespread adoption of new energy vehicles, in particular, increases the risk of spontaneous combustion, placing higher demands on the fire protection design of parking garages. Existing fire protection designs for mechanical automated parking garages mainly rely on building fire protection codes and steel structure fire protection technical specifications, but these codes often fail to fully consider the unique characteristics of mechanical automated parking garages, such as the impact of vehicle type, parking density, and ventilation conditions on the fire temperature rise curve. Therefore, it is necessary to develop a fire protection design method for mechanical automated parking garages to improve their safety and reliability in fires. To this end, we propose a fire protection design method for mechanical automated parking garages. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a fire-resistant design method for a mechanical automated parking garage, solving the aforementioned problems.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a fireproof design method for a mechanical automated parking garage, comprising the following steps:

[0005] Step S1: Determine the fire resistance rating and specific fire temperature rise curve: Based on the parking garage's function (including the proportion of new energy vehicles) and the local fire protection regulations, the fire resistance rating is determined to be Class I; the battery combustion heat release rate and flame spread characteristics parameters are obtained through a new energy vehicle spontaneous combustion simulation experiment. Combined with the parking garage's parking density (corrected for dense load when the parking space spacing is ≤2.5m) and ventilation volume (corrected for enclosed space when the natural ventilation rate is <0.5 times / h), a specific fire temperature rise curve suitable for mechanical three-dimensional parking garages is constructed using FDS fire numerical simulation software. The specific fire temperature rise curve includes the temperature change patterns of the initial stage (0-5min) rapid temperature rise segment of battery thermal runaway, the stable stage (5-20min) continuous combustion segment, and the decay stage (after 20min).

[0006] Step S2, structural fire resistance dual-dimensional verification: Using the critical temperature method, based on the specific fire temperature rise curve determined in step S1, the maximum temperature rise of the main steel structure (columns, beams, supports, top dampers) at 15 min and 30 min of fire is calculated. The critical temperatures of each component (columns ≥ 640℃, beams ≥ 663℃, supports ≥ 659℃, damper connectors ≥ 600℃) are selected for verification to ensure that the maximum temperature rise of the components is lower than the critical temperature. At the same time, the bearing capacity method is used, introducing the local high temperature correction coefficient for new energy vehicle combustion (the correction coefficient for the component directly above the battery is 1.2), to verify the stability stress and strength stress of the components under high temperature (300-600℃) to ensure that they do not exceed the design value of steel strength under high temperature.

[0007] Step S3, Design of Layered Fire Protection Measures: Based on the calculation results of Step S2, the fire protection of the main steel structure is designed as follows: Columns and beams adopt a multi-layer coating system of "bottom layer anti-corrosion primer (dry film thickness ≥ 60μm) + middle layer intumescent fire-retardant coating (thickness calculated according to equivalent thermal resistance, ≥ 5mm for columns, ≥ 7mm for beams) + top layer heat insulation coating (dry film thickness ≥ 30μm)"; Garage operating equipment (charging piles, lifting and traversing mechanisms) adopts zoned fire isolation: a 1.5m wide fire isolation belt (laid with flame-retardant floor tiles) is set around the charging piles, and the motor of the lifting mechanism is covered with a fireproof cover (fire resistance limit ≥ 1.5h); Design of an active fire linkage system: after the automatic fire alarm system is triggered, the ventilation system is shut down and the sprinkler system is started within 30 seconds (sprinkler intensity in the new energy vehicle area ≥ 10L / (min·m)). 2 ) ), Activate the smoke control and exhaust system (exhaust volume ≥ 60m³) 3 / (h·m 2 Simultaneously, the fire emergency lighting and evacuation guidance system are activated.

[0008] Step S4, Fireproof structural reinforcement design: Utilizing an externally wrapped column base, internally filled with flame-retardant glass wool (bulk density ≥ 64 kg / m³). 3 The structure has an oxygen index ≥32%, an outer concrete layer with a strength grade ≥C30 and a thickness ≥200mm, and is reinforced with a two-way steel mesh (diameter ≥8mm, spacing ≤150mm). The beam-column and beam-beam connection nodes are made of high-strength bolt friction type connection (bolt strength grade ≥10.9), and the node plate surface is coated with an intumescent fireproof coating (thickness ≥8mm). The top damper is wrapped with 50mm thick fireproof cotton (thermal conductivity ≤0.04W / (m·K)) and equipped with a temperature sensor (threshold 300℃), which triggers the damper locking device when the temperature is high.

[0009] Step S5, Full-cycle Inspection and Maintenance: Develop a graded maintenance plan: Check the thickness of the fireproof coating on steel components quarterly using an ultrasonic thickness gauge (repainting is required if the deviation is ≤-10%), conduct functional tests on the active fire prevention linkage system every six months (simulate fire signals to verify that the linkage response time of sprinkler, smoke exhaust, and lighting is ≤60s), and test the concrete strength of the column bases in the new energy vehicle parking area (rebound method test) and the integrity of the fireproof cotton of the damper every year. Store the test data in the digital maintenance archive.

[0010] Preferably, the process of constructing the specific fire temperature rise curve in step S1 includes: selecting three different types of new energy vehicles (pure electric, plug-in hybrid, and hydrogen fuel cell) to conduct a 1:1 spontaneous combustion simulation experiment, and collecting the flame temperature field distribution within 0-30 minutes (sampling point spacing 0.5m, sampling frequency 1Hz).

[0011] The experimental data was imported into FDS software to establish a parking garage model containing 284 standard parking spaces (arranged in a size of 6m×2.5m). Three ventilation conditions (natural ventilation, mechanical ventilation, and closed system) and two parking densities (100% full and 60% full) were set. Eight sets of temperature-time curves were obtained through simulation. The final specific fire temperature rise curve was obtained by fitting the weighted average method (the weight of new energy vehicle type is allocated according to the actual parking ratio).

[0012] Preferably, in the critical temperature method calculation in step S2, the aging coefficient of the fire-retardant coating is introduced (corrected based on a service life of 5 years, with a correction factor of 0.9), and the formula for calculating the maximum temperature rise of the steel component is: Where T s T represents the highest temperature (°C) of the steel component. g R represents the temperature (°C) at the corresponding moment on a specific fire temperature rise curve. r The equivalent thermal resistance (m) of fire-retardant coating 2 ·℃ / W), α age ρ is the aging coefficient. s The density of steel (7850 kg / m³) 3 ), c s The specific heat capacity of steel is 600 J / (kg·℃) .

[0013] Preferably, in step S2, during the load-bearing capacity method verification, the design value f of the steel strength at high temperature is... T According to formula f T =η sT ×f×β local Calculate, where η sT is the high-temperature yield strength reduction factor (taken according to GB51249-2017), and f is the design strength of steel at room temperature (N / mm). 2 ), β localAs a local high-temperature correction factor (1.2 for the component directly above the battery in new energy vehicles, and 1.0 for other areas), the stability stress verification of the column must meet the following requirements. The strength stress calculation of the beam must meet the following requirements.

[0014] Preferably, in step S3, the middle layer of the multilayer coating system is an intumescent fireproof coating with an expansion ratio ≥20 times and a high-temperature carbonized layer compressive strength ≥0.3MPa; the top layer heat insulation coating is a ceramic microsphere modified acrylic coating, and its heat insulation performance at 1000℃ meets the requirement of a temperature difference of ≥300℃ between the two sides of the coating; the flame-retardant floor tiles of the fireproof isolation zone of the charging pile are made of magnesite material with an oxygen index ≥35% and a combustion performance that meets Class A in GB8624-2012.

[0015] Preferably, in step S3, the active fire prevention linkage system is set with priority logic: when the fire alarm signal comes from the new energy vehicle area, the sprinkler system in that area is activated first (delay 0s), and then the sprinkler system in the adjacent area is activated (delay 5s); when the temperature sensor detects that the component temperature is ≥400℃, the non-fire protection power supply of the garage is automatically cut off, and only the fire emergency power supply and the power supply of the damper locking device are retained.

[0016] Preferably, in step S4, the concrete layer of the outer column base is provided with drainage holes (hole diameter ≥ 50 mm, spacing ≤ 1.5 m) to prevent water accumulation in the foundation pit from causing corrosion of the steel column; the connection between the node plate and the web of the steel beam is filled with fireproof sealant (temperature resistance ≥ 1000℃) to prevent flames from entering through the gaps.

[0017] Preferably, in step S4, the fireproof cotton of the top damper is wrapped with a thin stainless steel plate (thickness ≥ 1.5 mm), and the surface of the stainless steel plate is coated with a high-temperature resistant and anti-corrosion coating (temperature resistance ≥ 600℃); the damper locking device adopts an electromagnetic drive structure, and its coil is wrapped with fireproof insulation material (temperature resistance ≥ 400℃) to ensure reliable locking function at high temperatures.

[0018] Preferably, in step S5, the quarterly fireproof coating inspection needs to cover all component types. Three test points (both ends and the middle) are selected for each component. When the thickness deviation of a single component test point is ≤-15%, the entire coating of the component needs to be recoated. When the concrete strength of the column base is tested annually, if the rebound value is lower than 90% of the design value, the core drilling method needs to be used for verification. If the verification fails, the outer carbon fiber cloth is used for reinforcement.

[0019] Preferably, the fire protection design verification step is also included: a scaled-down model of the parking garage is made at a 1:10 scale, and an alcohol torch is used to simulate the spontaneous combustion source of new energy vehicles (heat release rate ≥50kW). The temperature of steel components, the expansion effect of fireproof coating and the response time of active fire protection system are tested within 15 minutes. The verification results must meet the verification requirements of step S2. Otherwise, the process returns to step S1 to adjust the specific fire temperature rise curve or step S3 to optimize fire protection measures.

[0020] Compared with the prior art, the present invention provides a fireproof design method for a mechanical three-dimensional parking garage, which has the following beneficial effects:

[0021] Enhanced safety: Specific fire temperature rise curves make the calculation results more accurate (deviation from real new energy fire scenarios ≤10%), dual-dimensional calculations cover all key components, and the risk of structural collapse under high temperature is reduced by more than 80%.

[0022] Enhanced reliability: The service life of multi-layer fire-retardant coatings is extended to 8 years (compared to 3-5 years for traditional single-layer coatings), the active system linkage response time is ≤60s (compared to 3-5 minutes for traditional independent systems), and the fireproof isolation of equipment can prevent the spread of flames across areas;

[0023] Highly operable: The maintenance plan clearly defines the specific testing instruments (such as ultrasonic thickness gauges), the cycle (quarterly / semi-annual / annual), and the acceptance standards, making it easy to implement on-site;

[0024] Wide adaptability: Parameters can be adjusted according to the proportion of new energy vehicles parked in different regions and climate conditions (such as enhanced corrosion prevention in coastal areas), and it is suitable for various types of mechanical three-dimensional parking garages (lifting and traversing type, aisle stacking type, vertical lifting type). Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the fire prevention design method for a mechanical three-dimensional parking garage according to the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1 A fire prevention design method for a mechanical automated parking garage includes the following steps:

[0028] Step S1: Determine the fire resistance rating and specific fire temperature rise curve: Based on the parking garage's function (including the proportion of new energy vehicles) and the local fire protection regulations, the fire resistance rating is determined to be Class I; the battery combustion heat release rate and flame spread characteristics are obtained through a new energy vehicle spontaneous combustion simulation experiment. Combined with the parking garage's parking density (corrected for dense load when the parking space spacing is ≤2.5m) and ventilation volume (corrected for enclosed space when the natural ventilation rate is <0.5 times / h), a specific fire temperature rise curve suitable for mechanical multi-level parking garages is constructed using FDS fire numerical simulation software. The specific fire temperature rise curve includes the temperature change patterns of the initial stage (0-5min) rapid temperature rise segment of battery thermal runaway, the stable stage (5-20min) continuous combustion segment, and the decay stage (after 20min).

[0029] Step S2, structural fire resistance dual-dimensional verification: Using the critical temperature method, based on the specific fire temperature rise curve determined in step S1, the maximum temperature rise of the main steel structure (columns, beams, supports, top dampers) at 15 min and 30 min of fire is calculated. The critical temperatures of each component (columns ≥ 640℃, beams ≥ 663℃, supports ≥ 659℃, damper connectors ≥ 600℃) are selected for verification to ensure that the maximum temperature rise of the components is lower than the critical temperature. At the same time, the bearing capacity method is used, introducing the local high temperature correction coefficient for new energy vehicle combustion (the correction coefficient for the component directly above the battery is 1.2), to verify the stability stress and strength stress of the components under high temperature (300-600℃) to ensure that they do not exceed the design value of steel strength under high temperature.

[0030] Step S3, Layered Fire Protection Design: Based on the calculation results of Step S2, the fire protection design for the main steel structure is as follows: Columns and beams adopt a multi-layer coating system consisting of a base layer of anti-corrosion primer (dry film thickness ≥ 60 μm) + a middle layer of intumescent fire-retardant coating (thickness calculated based on equivalent thermal resistance, ≥ 5 mm for columns and ≥ 7 mm for beams) + a top layer of heat-insulating coating (dry film thickness ≥ 30 μm). Garage operating equipment (charging piles, lifting and traversing mechanisms) adopts zoned fire isolation: a 1.5 m wide fire isolation strip (laid with flame-retardant floor tiles) is set around the charging piles, and the lifting mechanism motor is encased in a fireproof cover (fire resistance limit ≥ 1.5 h). An active fire-fighting linkage system is designed: after the automatic fire alarm system is triggered, the ventilation system is shut down and the sprinkler system is activated within 30 seconds (sprinkler intensity in the new energy vehicle area ≥ 10 L / (min·m)). 2 ) ), Activate the smoke control and exhaust system (exhaust volume ≥ 60m³) 3 / (h·m 2 Simultaneously, the fire emergency lighting and evacuation guidance system are activated.

[0031] Step S4, Fireproof structural reinforcement design: Utilizing an externally wrapped column base, internally filled with flame-retardant glass wool (bulk density ≥ 64 kg / m³). 3The structure has an oxygen index ≥32%, an outer concrete layer with a strength grade ≥C30 and a thickness ≥200mm, and is reinforced with a two-way steel mesh (diameter ≥8mm, spacing ≤150mm). The beam-column and beam-beam connection nodes are made of high-strength bolt friction type connection (bolt strength grade ≥10.9), and the node plate surface is coated with an intumescent fireproof coating (thickness ≥8mm). The top damper is wrapped with 50mm thick fireproof cotton (thermal conductivity ≤0.04W / (m·K)) and equipped with a temperature sensor (threshold 300℃), which triggers the damper locking device when the temperature is high.

[0032] Step S5, Full-cycle Inspection and Maintenance: Develop a graded maintenance plan: Check the thickness of the fireproof coating on steel components quarterly using an ultrasonic thickness gauge (repainting is required if the deviation is ≤-10%), conduct functional tests on the active fire prevention linkage system every six months (simulate fire signals to verify that the linkage response time of sprinkler, smoke exhaust, and lighting is ≤60s), and test the concrete strength of the column bases in the new energy vehicle parking area (rebound method test) and the integrity of the fireproof cotton of the damper every year. Store the test data in the digital maintenance archive.

[0033] The process of constructing the specific fire temperature rise curve in step S1 includes: selecting three different types of new energy vehicles (pure electric, plug-in hybrid, and hydrogen fuel cell) to conduct a 1:1 spontaneous combustion simulation experiment, and collecting the flame temperature field distribution within 0-30 minutes (sampling point spacing 0.5m, sampling frequency 1Hz);

[0034] The experimental data was imported into FDS software to establish a parking garage model containing 284 standard parking spaces (arranged in a size of 6m×2.5m). Three ventilation conditions (natural ventilation, mechanical ventilation, and closed system) and two parking densities (100% full and 60% full) were set. Eight sets of temperature-time curves were obtained through simulation. The final specific fire temperature rise curve was obtained by fitting the weighted average method (the weight of new energy vehicle type is allocated according to the actual parking ratio).

[0035] In step S2, when using the critical temperature method for calculation, the aging coefficient of the fire-retardant coating is introduced (corrected based on a service life of 5 years, with a correction factor of 0.9). The formula for calculating the maximum temperature rise of steel components is as follows: Where T s T represents the highest temperature (°C) of the steel component. g R represents the temperature (°C) at the corresponding moment on a specific fire temperature rise curve. r The equivalent thermal resistance (m) of fire-retardant coating 2 ·℃ / W), α age ρ is the aging coefficient. s The density of steel (7850 kg / m³) 3 ), c s The specific heat capacity of steel is 600 J / (kg·℃) .

[0036] In step S2, during the load-bearing capacity method verification, the design value f of the steel strength at high temperature is... T According to formula f T =η sT ×f×β local Calculate, where η sT is the high-temperature yield strength reduction factor (taken according to GB51249-2017), and f is the design strength of steel at room temperature (N / mm). 2 ), β local As a local high-temperature correction factor (1.2 for the component directly above the battery in new energy vehicles, and 1.0 for other areas), the stability stress verification of the column must meet the following requirements. The strength stress calculation of the beam must meet the following requirements.

[0037] In step S3, the middle layer of the multi-layer coating system is an intumescent fireproof coating with an expansion ratio of ≥20 times and a high-temperature carbonized layer compressive strength of ≥0.3MPa; the top layer heat insulation coating is a ceramic microsphere modified acrylic coating, and its heat insulation performance at 1000℃ meets the requirement of a temperature difference of ≥300℃ between the two sides of the coating; the flame-retardant floor tiles of the fireproof isolation zone of the charging pile are made of magnesite material with an oxygen index of ≥35% and a combustion performance that meets Class A in GB8624-2012.

[0038] In step S3, the priority logic of the active fire prevention linkage system is set as follows: when the fire alarm signal comes from the new energy vehicle area, the sprinkler system in that area is activated first (delay 0s), and then the sprinkler system in the adjacent area is activated (delay 5s); when the temperature sensor detects that the component temperature is ≥400℃, the non-fire protection power supply of the garage is automatically cut off, and only the fire emergency power supply and the power supply of the damper locking device are retained.

[0039] In step S4, drainage holes (diameter ≥ 50 mm, spacing ≤ 1.5 m) are provided in the concrete layer of the outer column base to prevent water accumulation in the foundation pit from causing corrosion of the steel column; the connection between the node plate and the web of the steel beam is filled with fireproof sealant (temperature resistance ≥ 1000℃) to prevent flames from entering through the gaps.

[0040] In step S4, the fireproof cotton of the top damper is wrapped with a thin stainless steel plate (thickness ≥ 1.5 mm), and the surface of the stainless steel plate is coated with a high-temperature resistant and anti-corrosion coating (temperature resistance ≥ 600℃); the damper locking device adopts an electromagnetic drive structure, and its coil is wrapped with fireproof insulation material (temperature resistance ≥ 400℃) to ensure reliable locking function at high temperatures.

[0041] In step S5, the quarterly fireproof coating inspection must cover all component types. Three test points (both ends and the middle) should be selected for each component. When the thickness deviation of a single component test point is ≤-15%, the entire coating of the component must be recoated. When the concrete strength of the column base is tested annually, if the rebound value is lower than 90% of the design value, the core drilling method must be used for verification. If the verification fails, the outer carbon fiber cloth should be used for reinforcement.

[0042] It also includes fire protection design verification steps: make a scaled-down model of the parking garage at a 1:10 scale, use an alcohol torch to simulate the spontaneous combustion source of new energy vehicles (heat release rate ≥50kW), test the temperature of steel components, the expansion effect of fireproof coating and the response time of active fire protection system within 15 minutes, and the verification results must meet the verification requirements of step S2. Otherwise, return to step S1 to adjust the specific fire temperature rise curve or step S3 to optimize fire protection measures.

[0043] Example:

[0044] The following uses a 284-space vertical lift mechanical parking garage in Shenzhen (with 40% of the spaces occupied by new energy vehicles, a natural ventilation rate of 0.3 times / hour, and a parking space spacing of 2.2m) as an example to illustrate the implementation process of this invention:

[0045] Step S1: Determine the fire resistance rating and the specific fire temperature rise curve

[0046] Fire resistance rating: According to GB50016-2014 (2018 edition), the fire resistance rating is determined to be Class I, with a fire resistance limit of ≥3.0h for columns, ≥2.0h for beams, and ≥2.0h for supports;

[0047] Spontaneous combustion experiment of new energy vehicles: Three pure electric cars (battery capacity 70kWh) were selected for 1:1 spontaneous combustion simulation. Temperature data were collected from 0 to 30 minutes: from 0 to 5 minutes (thermal runaway stage), the temperature rose from 20℃ to 820℃; from 5 to 20 minutes (continuous combustion stage), the temperature stabilized at 780-800℃; and after 20 minutes (decay stage), the temperature dropped to 650℃.

[0048] FDS numerical simulation: A 284-parking-space model was established (6m × 2.5m / space), with three operating conditions set (100% full + natural ventilation, 60% full + mechanical ventilation, 100% full + sealed). Experimental data was imported for simulation, and a weighted average method (40% for pure electric vehicles, 30% for plug-in hybrid vehicles, and 30% for gasoline vehicles) was used to fit a specific fire temperature rise curve: T g = 20 + 800 × (1 - 0.4e) -0.3t -0.6e -0.05t (t is the duration of the fire, in minutes).

[0049] Step S2: Two-dimensional verification of structural fire resistance

[0050] Calculation using the critical temperature method:

[0051] Component parameters: Column (350×400×20, Q355B, critical temperature 640℃), Beam (WH350×250×10×16, Q355B, critical temperature 663℃), Damper connector (Q355B, critical temperature 600℃).

[0052] Equivalent thermal resistance of fire-retardant coating: column Rr = 0.1m 2 ·℃ / W, beam Rr=0.13m 2 ·℃ / W, damper connector Rr=0.15m 2 ·℃ / W;

[0053] Calculation results: After 15 minutes, the column temperature is 320℃ (<640℃), the beam temperature is 380℃ (<663℃), and the damper connector temperature is 350℃ (<600℃), which meets the requirements.

[0054] Bearing capacity method verification:

[0055] Local high temperature correction factor: β of the column directly above the battery local =1.2, other components β local =1.0;

[0056] Design strength value of steel at 400℃: f T =0.91×345×1.2=377N / mm 2 (column);

[0057] Column stability stress: N = 1393 kN, A = 28400 mm 2 ,

[0058] The requirements are met;

[0059] Beam strength stress:

[0060] M=78.9kN·m,Wn=1429000mm 3 , The requirements are met.

[0061] Step S3: Design of Layered Fire Protection Measures

[0062] Multi-layer coating for steel structures:

[0063] Base coat: Epoxy zinc-rich anti-corrosion primer (dry film thickness 60μm, salt spray resistance ≥1000h);

[0064] Intermediate layer: Intumescent fire retardant coating (5mm for columns, 7mm for beams, expansion ratio 25 times, compressive strength of charred layer 0.4MPa);

[0065] Topcoat: Ceramic microsphere thermal insulation coating (30μm, temperature difference of 320℃ at 1000℃);

[0066] Fireproof isolation of equipment:

[0067] Charging pile: Magnesite fire-retardant bricks (oxygen index 38%, Class A combustion performance) are laid within 1.5m around the charging pile, and the charging pile body is coated with fireproof paint (5mm thick).

[0068] Lifting mechanism: The motor is covered with an aluminum silicate fiber fireproof cover (fire resistance limit 2.0h);

[0069] Active fire alarm linkage system:

[0070] Linkage logic: Fire alarm → Ventilation shut off within 30 seconds → Sprinkler system activated (10L / (min·m) in new energy areas) 2 → Turn on the smoke exhaust (65m) 3 / (h·m 2 Emergency lighting is activated;

[0071] Temperature trigger: When the component temperature is ≥400℃, cut off the non-fire protection power supply and retain the damper power supply.

[0072] Step S4: Fire-resistant structural reinforcement design

[0073] Externally mounted column base:

[0074] Internal filling: Flame-retardant glass wool (64kg / m²) 3 (Oxygen index 35%)

[0075] The outer concrete casing is C30, 200mm thick, reinforced with Φ8@150 bidirectional steel mesh, and equipped with Φ50 drainage holes (spaced 1.2m apart).

[0076] Node connections:

[0077] Bolts: Grade 10.9 high-strength friction bolts; gusset plates are coated with 8mm thick intumescent fire-retardant paint.

[0078] Gap filling: High-temperature fireproof sealant (temperature resistance 1200℃);

[0079] Top damper:

[0080] Fireproof cotton: 50mm thick centrifugal glass wool (thermal conductivity 0.038W / (m·K)), wrapped with 1.5mm stainless steel plate (coated with 600℃ high temperature resistant anti-corrosion coating);

[0081] Temperature monitoring: 300℃ threshold sensor, triggering electromagnetic locking device.

[0082] Step S5: Full-cycle inspection and maintenance

[0083] Quarterly inspection:

[0084] Instrument: Ultrasonic thickness gauge (accuracy ±1μm);

[0085] Content: Fireproof coating thickness (columns ≥ 5mm, beams ≥ 7mm, deviation ≤ -10% requires recoating);

[0086] Six-month test:

[0087] Simulate a fire signal (press the manual alarm button) and verify the linkage response time (≤60s);

[0088] Annual inspection:

[0089] Column base concrete: strength tested by rebound method (≥27MPa; if unqualified, core drilling verification is required; carbon fiber cloth is used when reinforcement is needed);

[0090] Dampers: Check the integrity of the fireproof cotton (replace if the damaged area is >5%), and test the function of the locking device.

[0091] Step S6: Fire Protection Design Verification

[0092] A 1:10 scale model was created (including 10 parking spaces, with 40% of the vehicles being new energy vehicles), and a spontaneous combustion was simulated using an alcohol torch (heat release rate of 50kW).

[0093] At 15 minutes, the temperature of the steel column was 310℃ and the temperature of the beam was 370℃. The fireproof coating expanded normally (expansion ratio 23 times).

[0094] The active system response time is 45 seconds, and the sprinkler and smoke exhaust systems are functioning normally.

[0095] The verification results meet the design requirements, and no parameter adjustments are needed.

[0096] In this embodiment, all materials and equipment comply with current national standards: fire-retardant coatings comply with GB 14907-2018, high-strength bolts comply with GB / T 1228-2006, and concrete complies with GB 50010-2010 (2015 edition). For parking garages in different regions, the following parameters can be adjusted:

[0097] In cold northern regions: fire-retardant coatings can be selected using low-temperature curing types (curing temperature ≥ -5℃);

[0098] In high humidity areas: Water-repellent glass wool (water repellency ≥98%) can be used as the filling material for column bases;

[0099] For new energy vehicles accounting for more than 60%, the heat release rate weight needs to be increased for specific fire temperature rise curves (corrected to 60%).

[0100] Through the above implementation process, this invention can comprehensively improve the fire resistance of mechanical multi-level parking garages, providing a guarantee for the safe operation of urban parking facilities.

[0101] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fire prevention design method for a mechanical automated parking garage, characterized in that, Includes the following steps: Step S1: Determine the fire resistance rating and specific fire temperature rise curve: Based on the parking garage's function including the proportion of new energy vehicles and the local fire protection regulations, the fire resistance rating is determined to be Level 1; the battery combustion heat release rate and flame spread characteristics are obtained through a new energy vehicle spontaneous combustion simulation experiment. Combined with the parking garage's parking density and ventilation volume, a specific fire temperature rise curve suitable for mechanical three-dimensional parking garages is constructed using FDS fire numerical simulation software. The specific fire temperature rise curve includes the temperature change patterns of the initial stage (0-5 min) rapid temperature rise segment of battery thermal runaway, the stable stage (5-20 min) continuous combustion segment, and the decay stage (after 20 min). Step S2, structural fire resistance dual-dimensional verification: Using the critical temperature method, based on the specific fire temperature rise curve determined in step S1, the maximum temperature rise of the main steel structure, including columns, beams, supports, and top dampers, at 15 min and 30 min of fire is calculated. The critical temperatures of each component are selected for verification, with columns ≥640℃, beams ≥663℃, supports ≥659℃, and damper connectors ≥600℃, ensuring that the maximum temperature rise of the components is lower than the critical temperature. At the same time, the bearing capacity method is used, introducing the local high temperature correction coefficient for new energy vehicle combustion (the correction coefficient for the component directly above the battery is 1.2), to verify the stability stress and strength stress of the components under high temperature (300-600℃), ensuring that they do not exceed the design value of steel strength under high temperature. Step S3, design of layered fire protection measures: Based on the calculation results of step S2, design the fire protection of the main steel structure: The columns and beams adopt a multi-layer coating system of "bottom anti-corrosion primer (dry film thickness ≥60μm) + middle intumescent fire retardant coating (thickness calculated according to equivalent thermal resistance, column ≥5mm, beam ≥7mm) + top heat insulation coating (dry film thickness ≥30μm)". The garage operating equipment (charging piles, lifting and traversing mechanisms) adopts zoned fireproof isolation: a 1.5m wide fireproof isolation belt is set up around the charging piles, and the motor of the lifting mechanism is covered with a fireproof cover; Design an active fire alarm linkage system: After the automatic fire alarm system is triggered, the ventilation system will be shut down and the sprinkler system will be activated within 30 seconds (sprinkler intensity ≥10L / (min·m) in the area for new energy vehicles). 2 ) ), Activate the smoke control and exhaust system (exhaust volume ≥ 60m³) 3 / (h·m 2 Simultaneously, the fire emergency lighting and evacuation guidance system are activated. Step S4, Fireproof structural reinforcement design: Utilizing an externally wrapped column base, internally filled with flame-retardant glass wool (bulk density ≥ 64 kg / m³). 3 The structure has an oxygen index ≥32%, an outer concrete layer with a strength grade ≥C30 and a thickness ≥200mm, and is reinforced with a two-way steel mesh (diameter ≥8mm, spacing ≤150mm). The beam-column and beam-beam connection nodes are made of high-strength bolt friction type connection (bolt strength grade ≥10.9), and the node plate surface is coated with an intumescent fireproof coating (thickness ≥8mm). The top damper is wrapped with 50mm thick fireproof cotton (thermal conductivity ≤0.04W / (m·K)) and equipped with a temperature sensor (threshold 300℃), which triggers the damper locking device when the temperature is high. Step S5, Full-cycle Inspection and Maintenance: Develop a graded maintenance plan: Check the thickness of the fireproof coating on steel components quarterly using an ultrasonic thickness gauge (repainting is required if the deviation is ≤-10%), conduct functional tests on the active fire prevention linkage system every six months (simulate fire signals to verify that the linkage response time of sprinkler, smoke exhaust, and lighting is ≤60s), and test the concrete strength of the column bases in the new energy vehicle parking area (rebound method test) and the integrity of the fireproof cotton of the damper every year. Store the test data in the digital maintenance archive.

2. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, The process of constructing the specific fire temperature rise curve in step S1 includes: selecting three different types of new energy vehicles (pure electric, plug-in hybrid, and hydrogen fuel cell) to conduct a 1:1 spontaneous combustion simulation experiment, and collecting the flame temperature field distribution within 0-30 minutes (sampling point spacing 0.5m, sampling frequency 1Hz). The experimental data was imported into FDS software to establish a parking garage model containing 284 standard parking spaces (arranged in a size of 6m×2.5m). Three ventilation conditions (natural ventilation, mechanical ventilation, and closed system) and two parking densities (100% full and 60% full) were set. Eight sets of temperature-time curves were obtained through simulation. The final specific fire temperature rise curve was obtained by fitting the weighted average method (the weight of new energy vehicle type is allocated according to the actual parking ratio).

3. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S2, the critical temperature method calculation incorporates the aging coefficient of the fire-retardant coating (corrected for a service life of 5 years, with a correction factor of 0.9). The formula for calculating the maximum temperature rise of steel components is as follows: Where T s T represents the highest temperature (°C) of the steel component. g R represents the temperature (°C) at the corresponding moment on a specific fire temperature rise curve. r The equivalent thermal resistance (m) of fire-retardant coating 2 ·℃ / W), α age ρ is the aging coefficient. s The density of steel (7850 kg / m³) 3 ), c s The specific heat capacity of steel is 600 J / (kg·℃) .

4. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S2, during the load-bearing capacity method verification, the design value f of steel strength at high temperature is... T According to formula f T =η sT ×f×β local Calculate, where η sT is the high-temperature yield strength reduction factor (taken according to GB51249-2017), and f is the design strength of steel at room temperature (N / mm). 2 ), β local As a local high-temperature correction factor (1.2 for the component directly above the battery in new energy vehicles, and 1.0 for other areas), the stability stress verification of the column must meet the following requirements. The strength stress calculation of the beam must meet the following requirements.

5. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S3, the middle layer of the multi-layer coating system is an intumescent fireproof coating with an expansion ratio of ≥20 times and a high-temperature carbonized layer compressive strength of ≥0.3MPa; the top layer heat insulation coating is a ceramic microsphere modified acrylic coating, and its heat insulation performance at 1000℃ meets the requirement of a temperature difference of ≥300℃ between the two sides of the coating; the flame-retardant floor tiles of the fireproof isolation zone of the charging pile are made of magnesite material with an oxygen index of ≥35% and a combustion performance that meets Class A in GB8624-2012.

6. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S3, the active fire prevention linkage system sets priority logic: when the fire alarm signal comes from the new energy vehicle area, the sprinkler system in that area is activated first (delay 0s), and then the sprinkler system in the adjacent area is activated (delay 5s); when the temperature sensor detects that the component temperature is ≥400℃, the non-fire protection power supply of the garage is automatically cut off, and only the fire emergency power supply and the power supply of the damper locking device are retained.

7. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S4, drainage holes (diameter ≥ 50 mm, spacing ≤ 1.5 m) are provided in the concrete layer of the outer-encased column base to prevent water accumulation in the foundation pit from causing corrosion of the steel column; the connection between the node plate and the web of the steel beam is filled with fireproof sealant (temperature resistance ≥ 1000℃) to prevent flames from entering through the gaps.

8. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S4, the fireproof cotton of the top damper is wrapped with a thin stainless steel plate (thickness ≥ 1.5 mm), and the surface of the stainless steel plate is coated with a high-temperature resistant and anti-corrosion coating (temperature resistance ≥ 600℃). The damper locking device adopts an electromagnetic drive structure, and its coil is wrapped with fireproof insulation material (temperature resistance ≥ 400℃) to ensure reliable locking function at high temperatures.

9. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, In step S5, the quarterly fireproof coating inspection must cover all component types. Three test points (both ends and the middle) are selected for each component. When the thickness deviation of a single component test point is ≤-15%, the entire coating of the component must be recoated. When the concrete strength of the column base is tested annually, if the rebound value is lower than 90% of the design value, the core drilling method must be used for verification. If the verification fails, the outer carbon fiber cloth is used for reinforcement.

10. The fire protection design method for a mechanical automated parking garage according to claim 1, characterized in that, It also includes fire protection design verification steps: make a scaled-down model of the parking garage at a 1:10 scale, use an alcohol torch to simulate the spontaneous combustion source of new energy vehicles (heat release rate ≥50kW), test the temperature of steel components, the expansion effect of fireproof coating and the response time of active fire protection system within 15 minutes, and the verification results must meet the verification requirements of step S2. Otherwise, return to step S1 to adjust the specific fire temperature rise curve or step S3 to optimize fire protection measures.

Images