A device and method for detecting air leakage and fire resistance of a cavity floor structure

Abstract

The application relates to the technical field of performance detection of building construction, and discloses a cavity floor structure air leakage amount and fire resistance performance detection device and method, which is based on a floor specimen with a built-in cavity. The detection device comprises a fire test furnace, a pressure simulation device and an air tightness detection device. The fire test furnace is used for burning the specimen, the cavity in the specimen is used as a smoke exhaust duct to simulate air flow detection, and data comparison is carried out by combining air tightness detection before and after specimen combustion, so that the actual specimen fire bearing capacity can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of performance detection of building construction, in particular to a device and method for detecting the air leakage and fire resistance of a cavity floor structure with structural, ventilation and smoke exhaust functions. BACKGROUND

[0002] With the increasing demand for indoor space size and comfort, hollow floor, which is evolved from solid floor by removing the concrete that has little influence on stress and deformation, has become a new type of floor system widely used in the engineering field in China in recent years. Meanwhile, the smoke exhaust duct and fire-fighting duct of underground garage and large-scale shopping mall structures are large in size and occupy a large space, which seriously affects the net height of the structure. For the cavity floor, if the smoke exhaust duct is arranged at the bottom of the floor, the engineering value of the cavity cannot be realized, which seriously restricts the popularization and application of the cavity floor. Therefore, a new type of multifunctional cavity floor with structural, ventilation and smoke exhaust functions has become a new design trend.

[0003] Currently, the fire resistance of each building component is generally evaluated from three aspects in the field of building fire, namely, thermal insulation, integrity and functionality. The thermal insulation refers to the performance of the component to resist temperature transfer; the integrity refers to the ability of the component to maintain the surface intact and not to be burned through in the fire; and the functionality refers to the ability of the component to maintain the original function in the fire.

[0004] In order to ensure that the cavity floor achieves its design purpose, corresponding detection must be carried out according to its design function. The existing detection scheme for the floor includes the air leakage of the ventilation and smoke exhaust function, the fire resistance of the smoke exhaust and structural function, and the bearing capacity of the floor, which are detected one by one. However, during actual detection, a pressure device is arranged on the test piece to simulate the bearing of the test piece, so that the test piece is subjected to high temperature and pressure at the same time, and is in the most unfavorable thermal-mechanical coupling state. The basis for this is that the tensile and compressive capacity of steel and concrete will be weakened at high temperature, and the mechanical properties will recover to a certain extent after returning to normal temperature. Assuming that the bending stiffness of the test piece at the highest temperature in the furnace during testing is I1, the bending stiffness after experiencing high temperature and returning to normal temperature is I2, and the pressure applied at the loading point is F1, then the maximum vertical displacement of the test piece measured under thermal-mechanical coupling is The maximum vertical displacement of the test piece measured when the test piece is subjected to high temperature and pressure in sequence is where k1 is a calculation coefficient, which is obtained through the simply supported seat of the test piece and the concentrated force loading position, and the value of k1 is fixed when the experimental device is unchanged, and E is the elastic modulus of the material. According to the above analysis, since I1 < I2, w1 > w2, it can be seen that the influence of thermal-mechanical coupling on the test piece is different from the detection value obtained by the test piece in sequence under thermal-mechanical and bearing detection,

[0005] Therefore, the simulation of the specimen detection in the approximate actual environment, and the more accurate specimen deformation resistance, air tightness and fire resistance value are the problems to be solved. SUMMARY

[0006] The application can detect the functionality and safety of the specimen by simulating the performance of the specimen in the real working condition, and based on the current research on the new floor and the relevant specifications, a cavity floor structure air leakage and fire resistance performance detection device and method are proposed.

[0007] A cavity floor structure air leakage and fire resistance performance detection device based on a floor specimen with an internal cavity, the specimen includes a floor body, a plurality of cavities are sequentially arranged inside the floor body along the length direction of the floor body, and a rib beam is arranged between the plurality of cavities, a hidden pipe is arranged in each rib beam to communicate two adjacent cavities, one end of the floor body is provided with a connecting pipe connected with the cavity, and a smoke outlet is arranged on the lower surface of the other end of the floor body.

[0008] A fire test furnace is used to detect the fire resistance of a single surface of the floor body, and the furnace top is provided with a furnace opening, and the floor body bottom is arranged on the furnace opening.

[0009] A pressure simulation device is used to apply uniform pressure to the top of the floor body to simulate the actual limit weight borne by the floor body.

[0010] A displacement meter is arranged on the upper surface of the floor body and corresponds to the midpoint of each rib beam, and the displacement meter is used to detect the deformation value of the floor body under the combined action of high temperature and heavy pressure.

[0011] An air tightness detection device is connected with the connecting pipe and can be used to detect the air tightness difference of the floor body before and after the fire resistance detection, and judge whether there is a crack in the internal air tightness after combustion.

[0012] Further, the fire test furnace is a rectangular structure corresponding to the length of the floor body, a steel container for containing fuel is arranged in the hearth of the fire test furnace, and an opening is arranged on the side of the fire test furnace.

[0013] Further, a plurality of temperature measuring points are arranged on the upper surface of the floor body, and the plurality of temperature measuring points correspond to the midpoint of each rib beam and the center position of each cavity.

[0014] Further, the pressure simulation device comprises a counterforce frame, a beam of the counterforce frame is located above the floor body, a bottom of the beam is provided with a pressure detector, a jack vertically arranged below the pressure detector, and a distribution beam frame is arranged at a bottom of the jack, and a plurality of support seats for transmitting pressure are uniformly arranged between the distribution beam frame and the floor body.

[0015] Further, the air tightness detection device comprises a frequency converter, a fan, a rectifier and a connecting pipe, the frequency converter is electrically connected with the fan, the fan is connected with the rectifier, and an air outlet of the rectifier is connected with the connecting pipe.

[0016] Further, a first hidden pipe through which the flue gas flows from the smoke outlet to the floor body is provided with a differential pressure detection point opposite to the pipe opening at two ends, and the two differential pressure detection points are detected by a differential pressure gauge.

[0017] Further, an air pressure gauge is arranged at the geometric center of the cavity at the end of the flue gas flow direction.

[0018] Further, a detection method for air leakage and fire resistance of a cavity floor structure, the test piece is cut into two sections from the middle position, and the two sections are detected according to detection scheme ① and detection scheme ②, and the specific steps are as follows:

[0019] 1) Detection scheme ①, which comprises air leakage detection and fire resistance test during smoke exhaust;

[0020] S1: adding a required amount of fuel in the internal container of the test furnace, setting a simply supported support on the furnace opening, hoisting the test piece to the simply supported support, and sealing the gap between the test piece and the furnace wall by using sealing materials;

[0021] S2: installing a counterforce frame, a jack, a pressure detector and a displacement meter, and judging the deformation degree of the test piece by the value of the displacement meter;

[0022] S3: adjusting the power of the frequency converter, so that the pressure reading of the air pressure gauge is stable at the negative pressure detection static pressure limit value, and reading the differential pressure value ΔP1 of the differential pressure gauge and the frequency of the frequency converter;

[0023] S4: igniting the fuel in the furnace by using the furnace opening, and recording the test start time when the average temperature of the flue gas measured on the end section of the test piece reaches the corresponding temperature, and adjusting the frequency converter to stabilize the flue gas flow rate;

[0024] S5: continuously recording the temperature measured by the temperature data recording device at the temperature measuring point on the surface of the test piece;

[0025] S6: when the test time reaches the corresponding index of the fire resistance performance qualified standard, extinguishing the flame in the furnace and stopping heating;

[0026] S7: Wait for the internal temperature of the specimen and the furnace temperature to drop to room temperature. Adjust the frequency converter to keep the differential pressure value of the differential pressure gauge consistent with the value in step S3, and record the frequency value of the frequency converter at this time. Then turn off the fan and disconnect the specimen from the rectifier. After obtaining the frequency value in this step, compare it with the frequency value in S3. The ratio can be used to determine the crack situation in the specimen. If the ratio is close to 1, it can be determined that the specimen has few cracks. If the ratio is much greater than 1, it can be determined that there are many cracks.

[0027] S8: Hoist the specimen to the ground with the fire-exposed bottom side facing up and observe whether there is a transverse crack penetrating the short side of the specimen on the fire-exposed bottom side. If such a transverse crack appears, it means that the specimen has lost its structural function under the test conditions and its fire resistance has failed to meet the standard.

[0028] 2) Test Plan ②, which includes air leakage testing and fire resistance testing during non-smoke exhaust.

[0029] A1: Add the required amount of fuel to the container inside the test furnace, set up a simple support on the furnace opening, hoist the specimen onto the simple support, and seal the gap between the specimen and the furnace wall with sealing material.

[0030] A2: Install reaction frame, jack, pressure tester and displacement gauge, and judge the degree of deformation of the specimen by the value of displacement gauge;

[0031] A3: Adjust the power of the frequency converter to stabilize the pressure reading of the barometer at the negative pressure detection static pressure limit value, read the differential pressure value ΔP2 of the differential pressure gauge and the frequency of the frequency converter, then remove the fan and rectifier, and seal the connecting pipe with high temperature resistant material;

[0032] A4: Ignite the fuel in the furnace using the furnace wall opening. When the average temperature of the flue gas measured on the end section of the specimen reaches the corresponding temperature, the start time of the test should be recorded.

[0033] A5: Use a temperature data recording device to continuously record the temperature measured at the temperature measuring points on the surface of the specimen;

[0034] A6: When the test time reaches the corresponding index of the fire resistance performance qualification standard, extinguish the flame in the furnace and stop heating;

[0035] A7: Wait for the internal temperature of the specimen and the furnace temperature to drop to room temperature. Unblock the connecting pipe that was blocked in step A3. Install the rectifier and fan. Adjust the frequency converter to keep the differential pressure value of the differential pressure gauge consistent with the value in step A3. Record the frequency shown by the frequency converter at this time. Then turn off the fan and disconnect the specimen from the rectifier connection. After obtaining the frequency value in this step, compare it with the frequency value in A3. The ratio can be used to determine the crack situation in the specimen. If the ratio is close to 1, it can be determined that the specimen has few cracks. If the ratio is much greater than 1, it can be determined that there are many cracks.

[0036] A8: Hoist the test piece to the ground, the fire bottom up, observe whether the fire bottom appears transverse cracks through the short side of the test piece, if the transverse cracks appear, it indicates that the test piece loses the structural function under the test condition, and the fire resistance fails to meet the standard.

[0037] Compared with the prior art, the advantages of the present application are as follows:

[0038] 1. The present application is aimed at testing the floor structure with a cavity that can be used as a smoke exhaust pipe. This structure is different from the traditional solid floor, so the air tightness of the test piece needs to be considered when testing the test piece.

[0039] 2. The present application tests the test piece by testing the fire resistance of the test piece when the inner cavity is exhaust and when the inner cavity is not exhaust, i.e. detection scheme ① and detection scheme ②, with the following purposes:

[0040] a. Simulate the working condition of the fan under real fire conditions, which may run normally or may not run normally due to damage;

[0041] b. The fire resistance test when the smoke is exhausted, because the upper top plate is directly affected by the high temperature smoke, the upper surface temperature rises greatly, and this test requires higher thermal insulation of the component; during the non-exhaust fire resistance test, the airflow flowability is poor under the initial condition of the component, so if there is air leakage due to cracks, the internal air pressure change is more obvious, and this test requires higher integrity and functionality of the component.

[0042] 3. The present application realizes multiple data detection on one set of detection device, saving the time cost and funds of testing the test piece.

[0043] 4. In the conventional air tightness measurement technology, the air leakage is measured by a flow restrictor. In the present application, because the floor body is provided with a hidden pipe, the size and shape of the hidden pipe of different test pieces are different, and the flow restrictor cannot be exactly the same size as the hidden pipe, so it cannot completely block the hidden pipe. Therefore, pressure difference pressure detection points are arranged before and after the hidden pipe, and a differential pressure gauge is used instead of the flow restrictor. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a sectional view of the floor body;

[0045] Figure 2 is a structural diagram of the detection device of the present application;

[0046] Figure 3 is a side view of Figure 2 ;

[0047] Figure 4 is a temperature measurement point distribution diagram.

[0048] Figure label:

[0049] 1. Floor slab body; 2. Cavity; 3. Rib beam; 4. Concealed pipe; 5. Connecting pipe; 6. Smoke exhaust outlet; 7. Simply supported support; 8. Fire test furnace; 9. Steel container; 10. Temperature measuring point; 11. Reaction frame; 12. Jack; 14. Distribution beam; 15. Distribution longitudinal beam; 16. Pressure detector; 17. Frequency converter; 18. Fan; 19. Rectifier; 20. Barometer; 21. Differential pressure test point. Detailed Implementation

[0050] The technical solution of the present invention will be clearly and completely described below, in conjunction with the appendix. Figure 1 To be continued Figure 4 The following embodiments are described in detail. These embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0051] Example 1

[0052] like Figure 1 As shown, a device for testing the air leakage and fire resistance of a cavity floor structure is based on a floor specimen with built-in cavities. The specimen includes a floor body with multiple cavities sequentially formed along its length, spaced apart by ribs. Each rib contains a concealed pipe connecting two adjacent cavities. One end of the floor body has a connecting pipe communicating with a cavity, and the lower surface of the other end of the floor body has a smoke exhaust port. The inner wall of the cavity is coated with fire-resistant material. The testing device includes...

[0053] A fire testing furnace is used to test the fire resistance of one side of a floor slab. The furnace has an opening at the top, and the floor slab is supported on the bottom of the opening. Figure 4 As shown, multiple temperature measuring points are distributed on the upper surface of the floor slab body. These multiple temperature measuring points correspond to the midpoints of each rib beam and the center of each cavity, respectively. Figure 2 As shown, the fire test furnace is a cuboid structure corresponding to the length of the floor slab body. The furnace chamber of the fire test furnace is equipped with a steel container for holding fuel, and the side of the fire test furnace is provided with an opening for easy ignition.

[0054] like Figure 3As shown, a pressure simulation device is used to apply uniformly distributed pressure to the top of the floor slab to simulate the actual ultimate weight that the floor slab can bear. The pressure simulation device includes a reaction frame, the crossbeam of which is located above the floor slab. A pressure detector is installed at the bottom of the crossbeam, and a vertically installed jack is installed below the pressure detector. A distribution beam frame is provided at the bottom of the jack. Multiple supports for transmitting pressure are evenly distributed between the distribution beam frame and the floor slab. The distribution beam frame includes one transverse distribution beam and two longitudinal distribution beams. The midpoint of the transverse distribution beam is connected to the bottom of the jack, and the transverse distribution beam spans both sides of the floor slab. A longitudinal distribution beam is fixed at each end of the transverse distribution beam. The two ends of the longitudinal distribution beam extend horizontally to two trisection points along the length of the floor slab. Each distribution beam is provided with a set of supports for transmitting pressure between it and the floor slab.

[0055] There are multiple displacement gauges, all located on the upper surface of the floor slab body, and each is set to correspond to the midpoint of multiple rib beams. The displacement gauges are used to detect the deformation of the floor slab body under the combined action of high temperature and heavy pressure. In this scheme, the displacement gauges and some temperature measuring points located at the midpoints of the rib beams overlap with each other. However, since the temperature measuring sensors used at the temperature measuring points are probes and the wire structure occupies little space, the temperature measuring points and displacement gauges will not affect each other.

[0056] like Figure 2 As shown, an airtightness testing device, connected to a connecting pipe, can be used to detect the airtightness difference of the floor slab body before and after fire resistance testing, and to determine whether there are cracks in its internal airtightness after combustion. The airtightness testing device includes a frequency converter, a fan, a rectifier, and a connecting pipe. The frequency converter is electrically connected to the fan, the fan is connected to the rectifier, and the air outlet of the rectifier is connected to the connecting pipe. The flue gas enters the first concealed pipe through which the flue gas flows from the exhaust port. Two differential pressure detection points are respectively set at both ends of the concealed pipe, facing the pipe opening. The two differential pressure detection points are detected by differential pressure gauges. One differential pressure detection point is located in the cavity where the exhaust port is located, 15cm away from the concealed pipe opening, at a height equal to the geometric center of the concealed pipe cross-section. The other differential pressure detection point is located at the outlet of the concealed pipe, close to the geometric center of the outlet cross-section. A barometer is installed inside the cavity connected to the connecting pipe, i.e., the end of the flue gas flow direction, and the barometer is located at the geometric center of the cavity.

[0057] A method for testing the air leakage and fire resistance of a hollow floor structure involves cutting the specimen in half at the middle, and then subjecting the two sections to test schemes ① and ② respectively. The specific steps are as follows:

[0058] 1) Testing Plan ①, which includes air leakage testing and fire resistance testing during smoke exhaust;

[0059] S1: Add the required amount of fuel in the test furnace inner container, set up a simply supported support on the furnace mouth, hoist the test piece to the simply supported support, and seal the gap between the test piece and the furnace wall with sealing material;

[0060] S2: Install counterforce frame, jack, pressure detector and displacement meter, judge the deformation degree of the test piece through the value of the displacement meter; the pressure value applied by the jack should be according to the formula F2=k2PBL, wherein P is the design value of the uniform load of the floor in the project used by the test piece, B is the width of the strip-shaped cavity floor test piece, L is the length of the strip-shaped cavity floor test piece, and k2 is a safety adjustment coefficient, which is obtained through the simply supported support at the bottom of the floor body and the concentrated force loading position. For special, first-class, second-class, third-class and fourth-class buildings, k2 is respectively taken as 2.5, 2.3, 2.0, 1.7 and 1.5. Connect the displacement meter with the data acquisition instrument;

[0061] S3: Adjust the power of the frequency converter so that the pressure reading of the barometer is stable at the negative pressure detection static pressure limit value, and read the differential pressure value ΔP1 of the differential pressure meter and the frequency of the frequency converter;

[0062] S4: Ignite the fuel in the furnace through the opening in the furnace wall. When the average temperature of the flue gas measured on the cross section of the end of the test piece reaches the corresponding temperature, the test start time should be recorded, and the frequency converter should be adjusted to stabilize the flue gas flow rate;

[0063] S5: Use the temperature data recording device to continuously record the temperature measured by the temperature measuring point on the surface of the test piece;

[0064] S6: When the test time reaches the corresponding index of the fire resistance performance qualification standard, extinguish the flame in the furnace and stop heating;

[0065] S7: Wait for the internal temperature of the test piece and the temperature in the furnace to drop to room temperature, adjust the frequency converter so that the differential pressure value of the differential pressure meter remains the same as in step S3, and record the frequency value of the frequency converter at this time. Then, disconnect the test piece from the rectifier. After obtaining the frequency value of this step, compare it with the frequency value in step S3. Through the obtained ratio, the crack condition in the test piece can be judged. If the ratio is close to 1, it can be judged that the test piece has fewer cracks. If the ratio is much greater than 1, it can be judged that the test piece has more cracks;

[0066] S8: Hoist the test piece to the ground and place it with the fire-exposed bottom facing up. Observe whether there are transverse cracks that penetrate the short side of the test piece. If such transverse cracks appear, it means that the test piece has lost its structural function under the test conditions and its fire resistance has not met the standard;

[0067] 2) Detection scheme ②, which includes air leakage detection and non-exhaust smoke fire resistance performance test;

[0068] A1: Add the required amount of fuel in the test furnace inner container, set up a simply supported support on the furnace mouth, hoist the test piece to the simply supported support, and seal the gap between the test piece and the furnace wall with sealing material;

[0069] A2: Install counterforce frame, jack, pressure detector and displacement meter, and judge the deformation degree of the test piece through the value of the displacement meter;

[0070] A3: Adjust the power of the frequency converter so that the pressure reading of the air pressure gauge is stable at the negative pressure detection static pressure limit value, read the differential pressure value ΔP2 of the differential pressure gauge and the frequency of the frequency converter, then remove the fan and rectifier, and seal the connecting pipe with high-temperature resistant material;

[0071] A4: Ignite the fuel in the furnace through the opening in the furnace wall, and start recording the test start time when the average temperature of the flue gas measured on the cross section of the end of the test piece reaches the corresponding temperature;

[0072] A5: Continuously record the temperature measured by the temperature data recording device at the temperature measuring point on the surface of the test piece;

[0073] A6: When the test time reaches the corresponding index of the fire resistance performance qualification standard, extinguish the flame in the furnace and stop heating;

[0074] A7: Wait for the internal temperature of the test piece and the furnace temperature to drop to room temperature, unblock the connecting pipe sealed in step A3, install the rectifier and fan, adjust the frequency converter so that the differential pressure value of the differential pressure gauge remains the same as in step A3, and record the frequency shown by the frequency converter at this time, then turn off the fan and disconnect the test piece and the rectifier. After obtaining the frequency value of this step, compare it with the frequency value in step A3. Through the ratio obtained, the crack condition in the test piece can be judged. If the ratio is close to 1, it indicates that the test piece has fewer cracks. If the ratio is much greater than 1, it indicates that the test piece has more cracks;

[0075] A8: Hoist the test piece to the ground and place it with the fire-exposed bottom facing up. Observe whether there are transverse cracks that penetrate the short side of the test piece. If such transverse cracks appear, it indicates that the test piece has lost its structural function under the test conditions and its fire resistance has not met the standard;

[0076] Evaluation criteria for air tightness:

[0077] Air leakage Q A The calculation formula is: Where C is the outflow coefficient, ε is the expansion coefficient, d is the equivalent flow velocity diameter of the pipe cross section, β is the ratio of d to the equivalent flow velocity diameter D of the cavity cross section, ΔP is the static pressure difference measured by the differential pressure gauge, ρ is the gas density, and F3 is the developed area of the test piece excluding the inner wall of the cavity where the smoke outlet is located. When the air leakage Q A of any test piece exceeds the maximum air leakage limit, the test piece fails the air leakage test.

[0078] The qualified standard of air leakage of the tested piece is that the maximum air leakage and the detection static pressure do not exceed the following limit

[0079]

[0080] Note: The air pipe system is divided into 5 levels according to its use category, the maximum air leakage of the medium pressure air pipe should not be greater than B level, the maximum air leakage of the high pressure air pipe should not be greater than C level, and the air pipe with special requirements should not be greater than D level; the air leakage of the smoke exhaust, dust removal and low temperature air supply system should not be greater than B level; the air leakage of the purification air conditioning system of level 1 to 5 should not be greater than C level; E level is only used for air pipes with special purposes such as virology laboratories; P is the detection static pressure in the air pipe, and the unit is Pa.

[0081] The evaluation standard of fire resistance is:

[0082] The qualified standard of fire resistance of the tested piece is that when the fire resistance rating of the building is one, two and three, the fire resistance limit of the tested piece should be not less than 1.50h, 1.00h and 0.75h respectively, and if the temperature measured by the temperature measuring point on the surface of the test piece reaches 400 DEG C during the fire resistance test with smoke exhaust, the test is failed.

[0083] During the fire resistance test without smoke exhaust, the basis for determining whether the test is passed is the same as that of the fire resistance test with smoke exhaust.

[0084] If the test qualified rate of the fire resistance test with smoke exhaust and the fire resistance test without smoke exhaust is higher than a certain standard at the same time, the fire resistance of the batch product of the tested piece is qualified, and if any test qualified rate is lower than the standard, the fire resistance test is unqualified.

[0085] The evaluation standard of the deformation of the test piece under pressure is:

[0086] If the displacement measured by any displacement meter exceeds 0.002L during the test, the test is failed, and if the test piece is found to be obviously damaged during the test, the test is failed.

[0087] Example 2

[0088] As shown in Figure 1 The floor body for detection in detection scheme ① and detection scheme ② is provided with three cavities, the cross section of which is rectangular, the size of which is 1000mm*400mm, the total length of which is 3.6m, and the total width of which is 1.3m, the cross section of the hidden way is circular, the project of the batch test piece is the second-class building, which is used as a medium pressure air pipe, the fire resistance rating of the building is one, and the controlled variables during the test are as follows,

[0089] 1) Detection scheme ①, which includes air leakage detection and fire resistance test with smoke exhaust;

[0090] S1: add the required amount of fuel in the internal container of the test furnace, set a simply supported support on the furnace opening, hoist the test piece to the simply supported support, and seal the gap between the test piece and the furnace wall with sealing material;

[0091] S2: install the counterforce frame, jack, pressure detector, and displacement meter, the jack applies pressure to the test piece, the pressure value applied by the jack is F2 = 2.0 × P × 3600 mm × 1300 mm, where P is the design value of the uniform load of the floor in the project for which the test piece is used. Connect the displacement meter to the data acquisition instrument;

[0092] S3: adjust the power of the frequency converter so that the pressure reading of the barometer stabilizes at a negative pressure detection static pressure limit of 750 Pa, and read the differential pressure value ΔP2 of the differential pressure gauge and the frequency of the frequency converter;

[0093] S4: ignite the fuel in the furnace through the opening in the furnace wall, and when the average temperature of the flue gas measured on the cross section of the end of the test piece reaches 50°C, the test start time should be recorded, and the frequency converter is adjusted to stabilize the flue gas flow rate;

[0094] S5: continuously record the temperature measured by the temperature data recording device at the temperature measurement point on the surface of the test piece;

[0095] S6: when the test time reaches 1.5 hours, extinguish the flame in the furnace and stop heating;

[0096] S7: wait for the internal temperature of the test piece and the temperature in the furnace to drop to room temperature, adjust the frequency converter so that the differential pressure value of the differential pressure gauge remains the same as in step S3, and record the frequency value of the frequency converter at this time. Subsequently, the wind machine is turned off, and the connection between the test piece and the rectifier is disconnected. After obtaining the frequency value of this step, it is compared with the frequency value in step S3. Through the ratio obtained, the condition of the cracks in the test piece can be judged. If the ratio is close to 1, it can be judged that the test piece has fewer cracks. If the ratio is much greater than 1, it can be judged that the test piece has more cracks;

[0097] S8: hoist the test piece to the ground and place the fire-exposed bottom surface upward. Observe whether there are transverse cracks that penetrate the short side of the test piece. If such transverse cracks appear, it indicates that the test piece has lost its structural function under the test conditions and its fire resistance has not met the standard;

[0098] 2) Detection scheme II, which includes air leakage detection and non-exhaust smoke resistance test;

[0099] A1: add the required amount of fuel in the internal container of the test furnace, set a simply supported support on the furnace opening, hoist the test piece to the simply supported support, and seal the gap between the test piece and the furnace wall with sealing material;

[0100] A2: Install counterforce frame, jack, pressure detector and displacement meter, the jack applies pressure to the test piece, the pressure value applied by the jack is F2 = 2.3 x P x 3600 mm x 1300 mm, wherein P is the design value of the uniform load of the floor in the project for the test pieces in the batch. Connect the displacement meter to the data acquisition instrument;

[0101] A3: Adjust the power of the frequency converter so that the pressure reading of the barometer is stabilized at the negative pressure detection static pressure limit value of 750 Pa, read the differential pressure value ΔP2 of the differential pressure meter and the frequency of the frequency converter, then remove the fan and the rectifier, and block the connecting pipe with high-temperature resistant material;

[0102] A4: Ignite the fuel in the furnace through the opening in the furnace wall, and start recording the test start time when the average temperature of the flue gas measured on the cross section of the end of the test piece reaches 50℃;

[0103] A5: Use the temperature data recording device to continuously record the temperature measured by the temperature measuring point on the surface of the test piece, and observe whether there is obvious damage on the surface of the test piece;

[0104] A6: When the test time reaches 1.5 hours, extinguish the flame in the furnace and stop heating;

[0105] A7: Wait for the internal temperature of the test piece and the temperature in the furnace to drop to room temperature, unblock the connecting pipe blocked in step A3, install the rectifier and the fan, adjust the frequency converter so that the differential pressure value of the differential pressure meter remains 750 Pa consistent with the value in step A3, and record the frequency shown by the frequency converter at this time, then turn off the fan and disconnect the test piece and the rectifier. After obtaining the frequency value in this step, compare it with the frequency value in A3, and through the obtained ratio, the crack condition in the test piece can be judged. If the ratio is close to 1, it can be judged that the test piece has fewer cracks, and if the ratio is much greater than 1, it can be judged that the test piece has more cracks.

[0106] A8: Hoist the test piece to the ground and place it with the fire-exposed bottom facing up, and observe whether there is obvious damage on the fire-exposed bottom;

[0107] During the test, if the air leakage of the test piece under positive pressure detection and negative pressure detection respectively does not exceed 0.0352 x P 0.65 , the temperature measured by the upper surface temperature measuring point does not reach 400℃, the frequency of the fan recorded in step A7 is within 10% of the frequency of the fan recorded in step S3, and the displacement measured by any displacement meter during the test does not exceed 7.2 mm, and the test piece does not appear obvious damage, it is determined that the air leakage and fire resistance of the test piece in the batch are qualified, otherwise they are not qualified.

[0108] It should be finally pointed out that the above embodiments are merely used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the above embodiments can still be modified, or some or all of the technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A device for detecting air leakage and fire resistance of a cavity floor structure, characterized in that, The utility model relates to a kind of fire resistance test device of floor, including floor body, the cavity of multiple cavities is sequentially set in the inside of floor body along the length direction of floor body, and multiple cavities are spaced apart with rib beam, and each rib beam is provided with the hidden pipe for communicating two adjacent cavities, one end of the floor body is equipped with the connecting pipe being connected with cavity, and the lower surface of the other end of floor body is equipped with smoke outlet, the inner wall of the cavity is coated with fireproof material, and the detection device includes, fire test furnace is used to detect the fire resistance of the single surface of floor body, and the top of fire test furnace is equipped with furnace mouth, and the bottom of floor body is arranged on furnace mouth. Pressure simulation device is used to apply uniform pressure to the top of floor body to simulate the limit weight actually borne by floor body. Displacement meter, displacement meter has multiple, and is located on the upper surface of floor body, and is respectively set with the midpoint of multiple rib beams one by one, and displacement meter is used to detect the value of deformation generated by floor body under the joint action of high temperature and heavy pressure. Air tightness detection device is connected with connecting pipe, and can be used to detect the air tightness difference of floor body before and after fire resistance detection respectively, to judge whether crack exists in the air tightness of its inside after combustion. The pressure simulation device includes counterforce frame, the crossbeam of counterforce frame is located above floor body, the bottom of crossbeam is equipped with pressure detector, vertically arranged jack is installed below pressure detector, distribution beam frame is equipped at the bottom of jack, and multiple support for transmitting pressure is uniformly distributed between distribution beam frame and floor body. The air tightness detection device includes frequency converter, fan, rectifier and connecting pipe, the frequency converter is electrically connected with fan, fan is docked with rectifier, and the air outlet of rectifier is connected with connecting pipe. The first hidden pipe through which smoke flow enters floor body from smoke outlet is provided with one pressure difference detection point opposite to the pipe orifice at both ends respectively, and two pressure difference detection points are detected by differential pressure gauge. The inside of cavity, i. e. the end of smoke flow direction, is provided with air pressure gauge, and air pressure gauge is located at the geometric center of the cavity.

2. The air leakage and fire resistance performance detection device for a cavity floor structure according to claim 1, characterized in that, The fire test furnace is rectangular parallelepiped structure corresponding to the length of floor body, steel container for containing fuel is arranged in the hearth of fire test furnace, and opening is arranged on the side of fire test furnace.

3. The device for detecting the air leakage and fire resistance performance of a cavity floor structure according to claim 2, characterized in that, The upper surface of floor body is distributed with multiple temperature measuring points, and multiple temperature measuring points correspond to the midpoint of each rib beam and the center position of each cavity respectively.

4. A method for detecting the air leakage and fire resistance of the cavity floor structure according to any one of claims 1 to 3, characterized in that, During testing, the test piece is cut into two sections from the middle position, and the two sections are detected according to detection scheme ① and detection scheme ② respectively, and the specific steps are as follows: 1) detection scheme ①, detection scheme ① includes air leakage amount detection and fire resistance test during smoke exhaust; S1: add the required amount of fuel in the inner container of test furnace, set simple support on furnace mouth, hoist the test piece to simple support, and seal the gap between test piece and furnace wall by sealing material; S2: install counterforce frame, jack, pressure detector and displacement meter, and judge the deformation degree of test piece by the value of displacement meter; S3: adjust the power of frequency converter, so that the pressure reading of air pressure gauge is stable at negative pressure detection static pressure limit value, read the pressure difference value ΔP1 of differential pressure gauge and the frequency of frequency converter; S4: ignite the fuel in the furnace through the furnace wall opening, and record the test start time when the average temperature of the flue gas measured on the end section of the test piece reaches the corresponding temperature, and adjust the frequency converter to stabilize the flue gas flow rate; S5: continuously record the temperature measured by the temperature data recording device at the test piece surface temperature measurement point; S6: when the test time reaches the corresponding index of the fire resistance performance qualification standard, extinguish the flame in the furnace and stop heating; S7: wait for the internal temperature of the test piece and the furnace temperature to drop to room temperature, adjust the frequency converter to keep the differential pressure value of the differential pressure gauge consistent with the value in step S3, and record the frequency value of the frequency converter at this time, then turn off the fan and disconnect the test piece from the rectifier connection part; After obtaining the frequency value of this step, compare it with the frequency value in step S3, and the ratio obtained can be used to judge the crack condition in the test piece. If the ratio is close to 1, it can be judged that the test piece has fewer cracks, and if the ratio is much greater than 1, it can be judged that the test piece has more cracks; S8: hoist the test piece to the ground, place the fire-exposed bottom surface upwards, and observe whether there are transverse cracks that penetrate the short side of the test piece. If such transverse cracks appear, it means that the test piece has lost its structural function under the test conditions, and its fire resistance has failed to meet the standard. 2) Detection scheme ②, which includes air leakage detection and non-exhaust smoke fire resistance performance test; A1: add the required amount of fuel in the test furnace inner container, set up a simply supported support on the furnace opening, hoist the test piece to the simply supported support, and seal the gap between the test piece and the furnace wall with sealing material; A2: install counterforce frame, jack, pressure detector and displacement meter, and judge the deformation degree of the test piece by the value of the displacement meter; A3: adjust the power of the frequency converter to stabilize the pressure reading of the barometer at the negative pressure detection static pressure limit value, read the differential pressure value ΔP2 of the differential pressure gauge and the frequency of the frequency converter, then remove the fan and the rectifier, and seal the connection pipe with high-temperature resistant material; A4: ignite the fuel in the furnace through the furnace wall opening, and record the test start time when the average temperature of the flue gas measured on the end section of the test piece reaches the corresponding temperature; A5: continuously record the temperature measured by the temperature data recording device at the test piece surface temperature measurement point; A6: when the test time reaches the corresponding index of the fire resistance performance qualification standard, extinguish the flame in the furnace and stop heating; A7: wait for the internal temperature of the test piece and the furnace temperature to drop to room temperature, unblock the connection pipe sealed in step A3, install the rectifier and the fan, adjust the frequency converter to keep the differential pressure value of the differential pressure gauge consistent with the value in step A3, and record the frequency value of the frequency converter at this time, then turn off the fan and disconnect the test piece from the rectifier connection part; After obtaining the frequency value of this step, compare it with the frequency value in step A3, and the ratio obtained can be used to judge the crack condition in the test piece. If the ratio is close to 1, it can be judged that the test piece has fewer cracks, and if the ratio is much greater than 1, it can be judged that the test piece has more cracks; A8: hoist the test piece to the ground, place the fire-exposed bottom surface upwards, and observe whether there are transverse cracks that penetrate the short side of the test piece. If such transverse cracks appear, it means that the test piece has lost its structural function under the test conditions, and its fire resistance has failed to meet the standard.

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