Structural Safety
July 24, 2015
Title
Theoretical Explanation of Structural Reliability for the Structural Design
Abstract
The theoretical explanation is proposed to descript the Structural Design of Structural Reliability.
Keywords: Structural Reliability, Structural Design
I. Theoretical Explanation of Structural Reliability for the Structural Design
After the Reconstruction of Structural Reliability (C. M. Huang 2015) is proposed by C. M. Huang, the structural design must be changed to fit the design method of the structural reliability. In the structural reliability, the dead load does not have the variability, but the live load has the variability with the 20% uncertain probability. However, whatever the structural load is the dead load or live load, the fundamental error scope has the 30% uncertain probability.
In the earthquake and wind forces, they are defined as the accidental loads without any uncertain probability, and they are directly adopted by the engineering codes or engineer. In the Earthquake Theory of Water Wave, the vertical acceleration is defined as the 3/8 lateral acceleration, and the vertical acceleration can be 0.15m/s2 in the medium earthquake, 0.4m/s2. Actually, the medium earthquake is the standard condition for the excess of the dead load, and the stronger earthquake may be controlled by the earthquake or wind equation.
In the structural size, the error value is very similar to the normal distribution, and the sectional and length errors have several levels. The size errors include ±1.5cm, ±0.75cm, ±0.5cm, ±0.25cm, ±0.15cm, ±0.05cm in the sectional error, and the size errors include ±3.0cm, ±1.5cm, ±1.0cm, ±0.5cm, ±0.3cm, ±0.1cm in the length error. In the thin structure, the size error is ±0.1cm in the sectional error, and the size error is ±0.01cm in the thickness error.
In the structural design, the elastic design of materials is adopted as the design standard, and the yield ratio have the higher value to raise the plastic deformation. Besides, the material strength of the structural experiment is very similar to the Type I distribution in statistics, and the scope of the yield stress can be defined as the minimum (-4%), standard, and maximum values (+16%).
According to the structural experiment of the yield stress, the yield stress, Fy, is defined by the 0.2% strain of the experimental material, and the elastic modulus, E, can be calculated by the equation, E=Fy/0.002. The Poisson ratio, ν, is known to calculate the shear modulus, G, and the relationship of G and E can defined by the following equation (Gere & Timoshenko 1972). In the design method of structural reliability, the E and G adopt the theoretical values to calculate the structural strength, and the two values have the minimum, standard, and maximum values.
In the metal materials, the residual stress must be considered to reduce the yield stress, and the adopted yield stress does not include the residual stress. In the concrete structures, the concrete strength should follow the minimum, standard, and maximum values to execute, and the residual stress of the rebar must be considered to reduce the yield stress in the structural design.
References
C. M. Huang (2015) "Reconstruction of Structural Reliability," Doctoral Dissertation in Mathematics, Registered Number: 2010370005, Institute of Disaster Prevention and Mitigation Engineering, Department of Civil Engineering, Tsinghua University, Beijing 100084, P.R.C., Supervisor: C. Dong, Ph.D. Aircraft, Jul. 12, 2015
J. M. Gere & S. P. Timoshenko (1972) Mechanics of Materials, D. Van Nostrand Company
July 24, 2015
Title
Theoretical Explanation of Structural Reliability for the Structural Design
Abstract
The theoretical explanation is proposed to descript the Structural Design of Structural Reliability.
Keywords: Structural Reliability, Structural Design
I. Theoretical Explanation of Structural Reliability for the Structural Design
After the Reconstruction of Structural Reliability (C. M. Huang 2015) is proposed by C. M. Huang, the structural design must be changed to fit the design method of the structural reliability. In the structural reliability, the dead load does not have the variability, but the live load has the variability with the 20% uncertain probability. However, whatever the structural load is the dead load or live load, the fundamental error scope has the 30% uncertain probability.
In the earthquake and wind forces, they are defined as the accidental loads without any uncertain probability, and they are directly adopted by the engineering codes or engineer. In the Earthquake Theory of Water Wave, the vertical acceleration is defined as the 3/8 lateral acceleration, and the vertical acceleration can be 0.15m/s2 in the medium earthquake, 0.4m/s2. Actually, the medium earthquake is the standard condition for the excess of the dead load, and the stronger earthquake may be controlled by the earthquake or wind equation.
In the structural size, the error value is very similar to the normal distribution, and the sectional and length errors have several levels. The size errors include ±1.5cm, ±0.75cm, ±0.5cm, ±0.25cm, ±0.15cm, ±0.05cm in the sectional error, and the size errors include ±3.0cm, ±1.5cm, ±1.0cm, ±0.5cm, ±0.3cm, ±0.1cm in the length error. In the thin structure, the size error is ±0.1cm in the sectional error, and the size error is ±0.01cm in the thickness error.
In the structural design, the elastic design of materials is adopted as the design standard, and the yield ratio have the higher value to raise the plastic deformation. Besides, the material strength of the structural experiment is very similar to the Type I distribution in statistics, and the scope of the yield stress can be defined as the minimum (-4%), standard, and maximum values (+16%).
According to the structural experiment of the yield stress, the yield stress, Fy, is defined by the 0.2% strain of the experimental material, and the elastic modulus, E, can be calculated by the equation, E=Fy/0.002. The Poisson ratio, ν, is known to calculate the shear modulus, G, and the relationship of G and E can defined by the following equation (Gere & Timoshenko 1972). In the design method of structural reliability, the E and G adopt the theoretical values to calculate the structural strength, and the two values have the minimum, standard, and maximum values.
In the metal materials, the residual stress must be considered to reduce the yield stress, and the adopted yield stress does not include the residual stress. In the concrete structures, the concrete strength should follow the minimum, standard, and maximum values to execute, and the residual stress of the rebar must be considered to reduce the yield stress in the structural design.
References
C. M. Huang (2015) "Reconstruction of Structural Reliability," Doctoral Dissertation in Mathematics, Registered Number: 2010370005, Institute of Disaster Prevention and Mitigation Engineering, Department of Civil Engineering, Tsinghua University, Beijing 100084, P.R.C., Supervisor: C. Dong, Ph.D. Aircraft, Jul. 12, 2015
J. M. Gere & S. P. Timoshenko (1972) Mechanics of Materials, D. Van Nostrand Company
