CN113801980A - Method for calculating strength change of building reinforcing steel bar after fire water cooling - Google Patents
Method for calculating strength change of building reinforcing steel bar after fire water cooling Download PDFInfo
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- CN113801980A CN113801980A CN202111089310.1A CN202111089310A CN113801980A CN 113801980 A CN113801980 A CN 113801980A CN 202111089310 A CN202111089310 A CN 202111089310A CN 113801980 A CN113801980 A CN 113801980A
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- reinforcing steel
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- copper pipe
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- 229910001294 Reinforcing steel Inorganic materials 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000001816 cooling Methods 0.000 title claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 12
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 42
- 239000010959 steel Substances 0.000 claims abstract description 42
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- 238000012360 testing method Methods 0.000 claims abstract description 10
- 230000005674 electromagnetic induction Effects 0.000 claims abstract description 8
- 238000005516 engineering process Methods 0.000 claims abstract description 8
- 238000004321 preservation Methods 0.000 claims abstract description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 15
- 229910052802 copper Inorganic materials 0.000 claims description 15
- 239000010949 copper Substances 0.000 claims description 15
- 239000000498 cooling water Substances 0.000 claims description 3
- 230000002787 reinforcement Effects 0.000 claims description 3
- 230000006698 induction Effects 0.000 claims 1
- 238000013461 design Methods 0.000 abstract description 3
- 230000009970 fire resistant effect Effects 0.000 abstract description 3
- 230000002045 lasting effect Effects 0.000 abstract description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000004566 building material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/42—Induction heating
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/15—Correlation function computation including computation of convolution operations
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Organic Chemistry (AREA)
- Data Mining & Analysis (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Mathematical Analysis (AREA)
- Theoretical Computer Science (AREA)
- Thermal Sciences (AREA)
- Computational Mathematics (AREA)
- General Engineering & Computer Science (AREA)
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- Databases & Information Systems (AREA)
- Computing Systems (AREA)
- Algebra (AREA)
- Building Environments (AREA)
Abstract
The invention discloses a method for calculating strength change of building reinforcing steel bars after fire water cooling. The invention adopts the electromagnetic induction heat treatment technology to heat, can better simulate the actual fire field temperature, realize rapid heating, can realize lasting heat preservation for 3.5 hours, provides technical support for simulating the fire field condition for a long time, can provide accurate data for tests, provides data guarantee for the fire-resistant design of the structure, and provides basis for popularizing and using novel 600MPa steel bars in the building engineering.
Description
Technical Field
The invention relates to the technical field of metal materials, in particular to a method for calculating strength change of building reinforcing steel bars after fire water cooling.
Background
In 2001, in 9.11 events, two steel structure buildings with 110 layers and 411m height in the world trade center in New York were collapsed due to fire after the airplane crashed, and 2830 people died. The collapse is mainly caused by the structural strength reduction caused by the high temperature caused by the fuel combustion after the airplane is impacted. In the cooked food processing workshop of the Zhengda corporation in Qingdao 2003, a fire disaster occurs, the steel roof truss processing workshop collapses in less than 30min, and the steel roof truss deforms and collapses in a large deflection mode when a factory building burns. In 2005, a 32-storey WINDSOR building located in Madri started to catch fire, partial building structures of the building collapsed, and the main body remained upright. In 2013, 6, 2 months and 2 days, oil residue tanks of petroleum major petrochemical company branch companies explode, 2 persons lose track and two persons are seriously injured due to fire burning, and the tank body collapses in burning.
The temperature is lower in the initial stage of fire, the difference of the mechanical properties of steel is smaller compared with the normal temperature, the structure still has enough bearing capacity, and enough time can be provided for rescue and evacuation of people; the burning time of the building is long and the temperature is relatively high in the middle and later stages of the fire, the yield strength and the ultimate strength of the steel are reduced when reaching 500-650 ℃, the elongation is improved, the steel structure is subjected to large-deflection deformation by the load borne by the steel structure, the mechanical property of the steel is further reduced by the temperature rise, and the bearing capacity of the structure is lost and the structure is unstably collapsed when the load borne by the building exceeds the ultimate bearing capacity of the structure. If the fire is not extinguished in the combustion process, the reinforcing steel bars are heated at high temperature for a long time, the yield strength and the ultimate strength of the reinforcing steel bars are reduced after the reinforcing steel bars are naturally cooled, but the elongation of the reinforcing steel bars is increased, and a remarkable sign can be generated before the building collapses.
With the development of the times, building materials are gradually strengthened highly, high-strength steel bars have the characteristics of high strength, good ductility and the like, raw materials can be saved to a great extent by using the high-strength steel bars, under the condition of the same bearing capacity, the main steel bars with smaller section sizes can be used by using the structure using the high-strength steel bars, 400 MPa-grade steel bars are generally used as the main steel bars for buildings abroad in the 20 th century and the 400 MPa-grade steel bars are used for replacing the 400 MPa-grade steel bars in engineering in some developed countries in the middle of the 90 th century, low-cost 600MPa steel bars with good comprehensive performance are continuously developed, and the 600 MPa-grade steel bars are put into use at present. At present, high-strength steel bars in China are still in the process of popularization and use, and steel bars above 400MPa are gradually used as construction main reinforcing steel bars from 2010, and 300MPa steel bars are eliminated. The high-strength steel bar has great use amount in high-rise and super high-rise buildings, and once a fire occurs in the high-rise and super high-rise buildings, the requirement for the residual bearing capacity of the structure is higher than that of a low-rise building due to the large dead weight of the high-strength steel bar, so that the research on the mechanical property of the high-strength steel bar at high temperature and after high temperature is of great significance, and the research result can be used for structural fire-resistant design calculation.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for calculating the strength change of a building reinforcing steel bar after fire water cooling, which has the advantages of high temperature rise speed, low energy consumption, good economic effect and high reliability of test results, and can better simulate the actual fire scene situation.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for calculating strength change of building reinforcing steel bars after fire water cooling adopts an electromagnetic induction heat treatment technology to heat the reinforcing steel bars, and after the reinforcing steel bars are heated to a preset temperature, the temperature is kept for 3.5 hours; and after the heat preservation is finished, immediately putting the steel bar into cooling water for cooling, and then testing the yield strength of the cooled steel bar to obtain the test data of the yield strength.
The electromagnetic induction heat treatment technology is characterized in that a spiral conductive round copper pipe is used as a heating device, in the heating process, the circular copper pipe is electrified with current of 6.5A, eddy current is formed in the spiral, and the reinforcing steel bar is placed in the middle of the spiral to be heated under the influence of the eddy current.
The thickness of the round copper pipe is 2mm, the inner diameter of the round copper pipe is 10mm, the thread pitch of the round copper pipe is 15cm, and the spiral inner diameter of the round copper pipe is 10-12 times of the diameter of the steel bar.
The preset temperature is 200-900 ℃, and in the range, the temperature interval is divided into 575 ℃ or less, 575 ℃ or more, 725 ℃ or less and 725 ℃ or more, and the formula (1) is established:
in the formula, T-fire field temperature, fy-the yield strength of the steel reinforcement at normal temperature,
and (4) the yield strength of the steel bars corresponding to different fire field temperatures.
Due to the adoption of the technical scheme, compared with the prior art, the electromagnetic induction heating system disclosed by the invention has the advantages that the temperature is increased by adopting an electromagnetic induction heating technology, the actual fire field temperature can be well simulated, the rapid temperature increase is realized, the lasting heat preservation for 3.5 hours can be realized, the technical support is provided for simulating the fire field condition for a long time, the accurate data can be provided for the test, the data guarantee is provided for the fire-resistant design of the structure, and the basis is provided for popularizing and using the novel 600MPa steel bar in the building engineering.
Detailed Description
The embodiment of the invention comprises the following steps: a method for calculating strength change of building reinforcing steel bars after water cooling in fire disaster comprises the steps of carrying out temperature rise treatment on the reinforcing steel bars by adopting an electromagnetic induction heat treatment technology, adopting a spiral conduction round copper pipe as a heating device, wherein in the heating process, the electrifying current of the round copper pipe is 6.5A, forming vortex in the spiral, the thickness of the round copper pipe is 2mm, the inner diameter is 10mm, the thread pitch is 15cm, and the spiral inner diameter is 12 times of the diameter of the reinforcing steel bars. Placing the steel bars in the spiral middle, heating under the influence of eddy current, and keeping the temperature for 3.5 hours; and after the heat preservation is finished, immediately putting the steel bar into cooling water for cooling, and then testing the yield strength of the cooled steel bar to obtain the test data of the yield strength.
The predetermined temperature is 200 ℃ and 900 ℃, and within the range, the temperature interval is divided into 575 ℃ or less, 575 ℃ or more, 725 ℃ or less and 725 ℃ or more, and the formula (1) is established:
in the formula, T-fire field temperature, fy-the yield strength of the steel reinforcement at normal temperature,
and (4) the yield strength of the steel bars corresponding to different fire field temperatures.
The table above shows the test data, and after 3.5 hours of constant temperature heating and water cooling, the yield strengths of the steel bars corresponding to different heating temperatures are obtained.
Claims (5)
1. A method for calculating strength change of building reinforcing steel bars after fire water cooling is characterized by comprising the following steps: heating the reinforcing steel bars by adopting an electromagnetic induction heat treatment technology, heating the reinforcing steel bars to a preset temperature, and keeping the temperature for 3.5 hours; and after the heat preservation is finished, immediately putting the steel bar into cooling water for cooling, and then testing the yield strength of the cooled steel bar to obtain the test data of the yield strength.
2. The method for calculating the strength change of the building reinforcing steel bars after fire water cooling according to claim 1, wherein the method comprises the following steps: the electromagnetic induction heat treatment technology is characterized in that a spiral conductive round copper pipe is used as a heating device, in the heating process, the circular copper pipe is electrified with current of 6.5A, eddy current is formed in the spiral, and the reinforcing steel bar is placed in the middle of the spiral to be heated under the influence of the eddy current.
3. The method for calculating the strength change of the building reinforcing steel bars after fire water cooling according to claim 2, wherein the method comprises the following steps: the thickness of the round copper pipe is 2mm, the inner diameter of the round copper pipe is 10mm, the thread pitch of the round copper pipe is 15cm, and the spiral inner diameter of the round copper pipe is 10-12 times of the diameter of the steel bar.
4. The method for detecting the yield strength of the reinforcing steel bars after the simulated fire according to claim 2 or 3, is characterized in that: the steel bar is produced by a 600 MPa-level intelligent induction heat treatment technology with the diameter of 10mm-14 mm.
5. The method for calculating the strength change of the building reinforcing steel bars after fire water cooling according to claim 1, wherein the method comprises the following steps: the preset temperature is 200-900 ℃, and in the range, the temperature interval is divided into 575 ℃ or less, 575 ℃ or more, 725 ℃ or less and 725 ℃ or more, and the formula (1) is established:
in the formula, T-fire field temperature, fy-yield strength of the steel at ambient temperature, fy T-the yield strength of the reinforcement for different fire field temperatures.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111089310.1A CN113801980A (en) | 2021-09-16 | 2021-09-16 | Method for calculating strength change of building reinforcing steel bar after fire water cooling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111089310.1A CN113801980A (en) | 2021-09-16 | 2021-09-16 | Method for calculating strength change of building reinforcing steel bar after fire water cooling |
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| CN113801980A true CN113801980A (en) | 2021-12-17 |
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| CN202111089310.1A Pending CN113801980A (en) | 2021-09-16 | 2021-09-16 | Method for calculating strength change of building reinforcing steel bar after fire water cooling |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114354356A (en) * | 2021-12-31 | 2022-04-15 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating elongation of steel bar after open space severe fire |
| CN114397193A (en) * | 2021-12-31 | 2022-04-26 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating elongation of steel bar after general fire in closed space |
| CN114646545A (en) * | 2021-12-31 | 2022-06-21 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating strength of steel bar after severe fire in open space |
| CN114646538A (en) * | 2021-12-31 | 2022-06-21 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating strength of steel bar after general fire in closed space |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105095579A (en) * | 2015-07-21 | 2015-11-25 | 辽宁工程技术大学 | Method for simulating fire in high-rise building |
| CN111695179A (en) * | 2020-05-19 | 2020-09-22 | 广东交科检测有限公司 | Method for calculating mechanical property reduction coefficient of concrete bridge material after fire |
-
2021
- 2021-09-16 CN CN202111089310.1A patent/CN113801980A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105095579A (en) * | 2015-07-21 | 2015-11-25 | 辽宁工程技术大学 | Method for simulating fire in high-rise building |
| CN111695179A (en) * | 2020-05-19 | 2020-09-22 | 广东交科检测有限公司 | Method for calculating mechanical property reduction coefficient of concrete bridge material after fire |
Non-Patent Citations (3)
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|---|
| 杨斌等: "火灾后钢筋的强度检测方法研究", 《混凝土》 * |
| 秦培巧: ""高温后600MPa抗震钢筋受力特性试验及本构模型研究"", 《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》 * |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114354356A (en) * | 2021-12-31 | 2022-04-15 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating elongation of steel bar after open space severe fire |
| CN114397193A (en) * | 2021-12-31 | 2022-04-26 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating elongation of steel bar after general fire in closed space |
| CN114646545A (en) * | 2021-12-31 | 2022-06-21 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating strength of steel bar after severe fire in open space |
| CN114646538A (en) * | 2021-12-31 | 2022-06-21 | 贵州中建伟业建设(集团)有限责任公司 | Detection method for simulating strength of steel bar after general fire in closed space |
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Application publication date: 20211217 |