Nonlinear Finite Element Analysis of Temperature Field of High-Strength Concrete Columns in Modern Steel Structures X Feng Jiubin Liu Xueyan (Harbin Institute of Technology, Harbin 150090) Temperature field under disaster conditions. The calculation results are in good agreement with the test results, and the effects of different protective layer thicknesses (concrete and fire retardant coatings) and different diameters on the temperature field of concrete filled steel tube are considered, thus creating a further study on the fire resistance of high-strength concrete and the mechanical properties at high temperatures. condition. At present, high-strength concrete pipes have been widely used in practical engineering. 111, and corresponding fire-fighting technical specifications have not been developed at home and abroad. There are few studies on the fire-resistance of high-strength concrete members. Therefore, it is necessary to analyze the fire resistance of high-strength concrete columns with steel pipes. Based on this situation, this paper first analyzes the temperature field of high-strength concrete columns with steel pipes. A hybrid solution of finite element and finite difference is used, which uses finite element meshing in the spatial domain and finite difference meshing in the time domain. This is a successful combination. Because it makes full use of the advantages of the finite element method in spatial domain partitioning and the advantages of the finite difference method in time advancement. Based on the reasonable determination of the boundary conditions of the CFRP under fire conditions, based on the research results of many scholars at home and abroad on the heat resistance of concrete and steel and its influencing factors, the finite element and finite difference method are used to The temperature field of high-strength concrete (including the case with protective layer) was analyzed, and the theoretical calculation results were verified by the test results. 1The thermal performance of steel and concrete The thermal performance of steel and concrete is the basis for studying the fire resistance of concrete filled steel tube. Reasonable determination of the thermal performance parameters of steel and concrete is an important prerequisite for analyzing the temperature field of concrete filled steel tube. In the past, many scholars at home and abroad have carried out a lot of research work and obtained a series of research results. This paper will use the provided thermal performance parameters of steel and concrete to analyze the temperature field of high-strength concrete. The strength variation of high-strength concrete at high temperature is similar to that of ordinary concrete. 12. The compressive strength of high-strength concrete is about 10%~15% lower than normal temperature at 100~300*C; the compressive strength is when the temperature is 300~400*C. Recovery, even more than 8% to 10% of the strength at normal temperature; continue to increase the temperature, the concrete strength continues to decline, to 800C at room temperature and only 30% at room temperature. High temperature also makes the concrete change * This project is funded by the Ministry of Public Security Research Fund . Author: Feng Jiubin male born in May 1966 doctoral graduate shaped modulus decreased, but regardless of the strength of the concrete. However, another review report on high-strength concrete places special emphasis on the high-strength concrete's fire resistance is not as good as ordinary concrete, and emphasizes that this must be noted in the design. The report also believes that high-strength concrete will collapse at high temperatures earlier than ordinary concrete. The reason may be due to the high compactness of high-strength concrete, high internal temperature vaporization caused by high temperature, high pore pressure and non-diffusion, pore pressure. Caving occurs when the tensile strength of the concrete is exceeded. It is because the strength variation of high-strength concrete at high temperature is similar to that of ordinary concrete. This paper uses the provided thermal performance parameter expressions of steel and concrete to analyze the temperature field of high-strength concrete. However, since the fire resistance of high-strength concrete is not the same as that of ordinary concrete, it is appropriate to analyze the temperature field of high-strength concrete of steel pipe by using the thermal performance parameter expression of steel and concrete provided. The author carried out calculation and analysis of 42 foreign test data, and made 7 real test pieces. It is considered that it is feasible to calculate high-strength concrete of steel pipe by using the thermal performance parameters of ordinary concrete. The basis lies in: (1) the strength variation of high-strength concrete at high temperature is similar to that of ordinary concrete; (2) the concrete-filled steel tubular members are different from the reinforced concrete members, because the core concrete is in the three-direction stress and the temperature field of the concrete filled steel tube at high temperature is analyzed. The nonlinear finite element program TFACFST adjusts the direction of the interface with finite element mesh in the spatial domain, and revise the parameters such as diameter D to analyze the temperature field of high-strength concrete of steel tube at high temperature. 3 The test verified that the development of building fires was divided into the initial stage, the development stage and the falling stage. The initial stage of a building fire is generally short, and it quickly enters the development stage with intense combustion, and then the change tends to be flat, and the entire development phase lasts for a long time. The international standard heating curve ISO-834 and the Canadian heating curve CAN4*2 (if) are fire temperature heating models given by actual fires. The program TFACFST has strong versatility, and the calculation of plane problems or axisymmetric problems can be performed as long as some of the parameters are appropriately changed. The program is suitable for both uniform temperature field and non-uniform temperature field analysis; it is suitable for both circular section and polygon (such as square, rectangular and hexagonal) sections; it is suitable for protective layers. The situation applies to the case of no protection layer. The standard heating curve was verified by the program TFACFST, and the measured results of the temperature field of 49 concrete-filled steel tubular members at home and abroad under different cross-section dimensions were verified. The calculated results agree well with the experimental results. The measured results of the temperature field test of high-strength concrete pipe made in Canada are compared with the results of the finite element calculation in this paper. The temperature rise of the components is carried out according to the curve specified by the Canadian design specification CAN4-S101. In May 2000, the author compared the results of the finite element calculations in the temperature field test of high-strength concrete pipe made by the National Fixed Fire Extinguishing System and the Refractory Component Quality Inspection Center of the Tianjin Fire Research Institute of the Ministry of Public Security. The temperature rise of the components is carried out according to the international standard ISO-834 temperature rise curve. The strength of the concrete is / the thickness of the protective layer of the fireproof coating. The secondary fireproof coating adopts the TN-LS steel structure fireproof and heat insulation coating produced by Beijing Tianning Firefighting Co., Ltd. The performance meets the relevant national standards, and the basic performance of the coating is shown as The relationship between surface temperature and time of steel tube high-strength concrete under different outer diameters of different concrete protective layer thickness, the fire curve adopts ISO-834 heating curve. S is the thickness of the T-t relationship (China) concrete protective layer of mixed high-strength concrete. The T-t relationship of high-strength concrete with different thickness of concrete protection layer shows the relationship between surface temperature and time of steel tube high-strength concrete under different outer diameters of different fire-retardant coatings. The fire temperature rise curve is heated by ISO-834. curve. The thermal performance parameters of fire retardant coatings are as described above. It can be seen that with the increase of the thickness of the protective layer of concrete and fireproof coating, the amplitude of the curve of the surface temperature of the steel pipe is decreasing continuously; and the outer diameter of the steel pipe is larger, the lower the temperature of the surface of the steel pipe at the same temperature rise time, this Mainly due to the larger outer diameter of the steel pipe, the larger the concrete volume inside the pipe, the more heat is absorbed. a and b are the relationship between the outer diameter Ds of the high-strength concrete steel pipe and the surface temperature T1 of the steel pipe at a certain temperature rise time, and the relationship between the outer diameter Ds of the steel pipe and the core temperature T2 of the inner concrete. T-t relationship of high-strength concrete of steel tube under different protective layer thickness of fire-retardant coating (a)-DXt=254mmX6.35mm; (b)-DX Ds-T relationship curve a is the inner diameter D of steel tube and steel tube of high-strength concrete of steel tube at a certain temperature rise time The relationship between the surface temperatures T1. At the same temperature rise time, the larger the diameter of the steel pipe, the lower the temperature of the steel pipe surface. This is mainly because the larger the diameter of the steel pipe, the larger the concrete volume inside the pipe, the more heat is absorbed; and the larger the diameter, the more obvious the performance. As the fire time increases, this difference becomes smaller and smaller. b is the relationship between the inner diameter D of the steel pipe high-strength concrete at a certain temperature rise and the concrete temperature T2 at the inner surface D/4 of the steel pipe. At the same temperature rise time, the larger the diameter of the steel pipe, the lower the temperature of the concrete at D/4 from the inner surface of the steel pipe, mainly because the larger the diameter of the steel pipe, the longer the heat conduction distance of heat in the concrete, and the more heat is lost; The larger the diameter, the smaller the temperature rise at this point as the fire time increases. c is the relationship between the inner diameter D of the steel tube of the high-strength concrete at a certain temperature rise and the core temperature T3 of the concrete at the inner surface D/. The law and causes of change are similar to b. In this paper, 49 test data at home and abroad are analyzed, and the test results are in good agreement with the above theoretical calculation results. The following is a list of medium diameters between 168.340064mm and a wall thickness of 6.35. 4 Conclusions The existing research results on the thermal properties of steel and concrete, etc., using the prepared nonlinear D-T relationship curve time / s on the tower 12th Wind-induced acceleration response of particle point 4 Conclusion This paper simulates the pulsating wind load of Hefei TV Tower and its structure, M, C and K are the structural mass, damping and stiffness matrix respectively. Moreover, the work and X are acceleration, velocity and displacement respectively. Response vector; F(() is the downwind pulsating wind load vector. The 0 method (0=1.4) compiled the dynamic response calculation program of Hefei TV Tower. The wind vibration force response of the Hefei TV Tower is obtained under the simulated pulsating wind load sample, as shown. The calculation results show that the maximum peak displacement, velocity and acceleration response of the upper tower are 0964m, 0.725m/s and 0774m/s2, respectively, and the acceleration value greatly exceeds the allowable maximum acceleration limit (0.191m/s2). Therefore, the acceleration response of the tower on the tower is too large, and effective measures are needed to suppress its wind-induced response. Structural wind vibration response analysis. According to the relevant domestic building structure norms, considering the vertical correlation of the pulsating wind, the power spectral density function matrix of the pulsating wind load is established. The calculation method of spectrum representation and the selection of simulation parameters are discussed in detail. The time-series samples of 19 pulsating wind loads related to the vertical height of the tower acting on the Hefei TV Tower are simulated. On this basis, the wind-induced vibration response of Hefei TV Tower was calculated by time-history analysis method. The results show that the tower's acceleration response is too large, exceeding the human comfort limit, and effective measures are needed to suppress its wind-induced response. Fan Light,Ceiling Fan with Light,Ceiling Fans with LED Lights,LED Fan Light Yuyao Flylit Appliance Co.,Ltd , https://www.yyflylit.com
Nonlinear Finite Element Analysis of Temperature Field of Steel Tube High Strength Concrete Column
Nonlinear Finite Element Analysis of Temperature Field of High-Strength Concrete Columns in Modern Steel Structures X Feng Jiubin Liu Xueyan (Harbin Institute of Technology, Harbin 150090) Temperature field under disaster conditions. The calculated results are in good agreement with the test results, taking into account the different protective layer thickness (concrete and fire retardant coatings) and different straight