Browsing by Author "Cheng, FP"

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Effect of strength and fiber reinforcement on fire resistance of high-strength concrete columns
(2003-02-01)
Kodur, VKR
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Cheng, FP
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Wang, TC
;
Sultan, MA
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土木工程學系
In this paper, results from fire resistance experiments on five types of reinforced concrete columns are presented. The variables considered in the study include concrete strength [normal-strength concrete (NSC) and high-strength concrete (HSC)], aggregate type (siliceous and carbonate aggregate), and fiber reinforcement (steel and polypropylene fibers). Data from the study is used to determine the structural behavior of HSC columns at elevated temperatures. A comparison is made of the fire resistance performance of HSC columns with that of NSC and fiber-reinforced HSC columns. The factors that influence the thermal and structural behavior of HSC concrete columns under fire conditions are discussed. The results show that the fire resistance of a NSC column is higher than that of a HSC column. Also, the addition of polypropylene fibers and the use of carbonate aggregate improve fire resistance.
Fourier series expansion method for plated-structures
(1999-10-01)
Deng, JG
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Cheng, FP
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土木工程學系
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Department of Civil Engineering
This work applies a structural analysis method based on an analytical solution from the Fourier series which transforms a half-range cosine expansion into a static solution involving plated structures. Two sub-matrices of in-plane and plate-bending problems are also formulated and coupled with the prescribed boundary conditions for these variables, thereby providing a convenient basis for a numerical solution. In addition, the plate connection are introduced by describing the connection between common boundary continuity and equilibrium. Moreover, a simple computation scheme is proposed. Numerical results are then compared with finite element results, demonstrating the numerical scheme's versatility and accuracy.
Fourier series method for plane elastic problems of polygonal domain
(2001)
Deng, JG
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Cheng, FP
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土木工程學系
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Department of Civil Engineering
This study employs the Fourier series method based on the edge function approach to solve the plane elastic problem of polygonal domain described by Navier equations. The analytical solutions serve as a set of fundamental solutions for each edge. Superposing the solution function and matching the prescribed boundary conditions in each edge allows the solving of the unknown variables and the analysis of the problem. An extra corner function and regularization technique is utilized to enhance convergence rate. Only one element is required to analyze which polygon domain is convex, however, by dividing a non-convex shape into several convex shapes, the proposed method can be extended to irregular geometrical shape. Numerical examples demonstrate the merits of the developed scheme, as well as its efficiency and accuracy. (C) 2001 Elsevier Science B.V. All rights reserved.
Fuzzy pattern recognition model for diagnosing cracks in RC structures
(1998-04-01)
Chao, CJ
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Cheng, FP
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土木工程學系
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Department of Civil Engineering
This paper examines a diagnostic model based on the concept of cause-and-effect diagramming and fuzzy pattern recognition, which contributes a new methodology for diagnosing engineering problems. Three examples are presented to demonstrate the feasibility of the model in diagnosing crack formations in reinforced concrete structures. Two levels of parameters representing the causes of cracks in concrete are used to form fuzzy sets. The parameters represent the materials used, fabrication of structural elements, loading, and environmental conditions. An expert system that links the parameters by means of fuzzy set theory is constructed using finite universal sets consisting of membership functions and fuzzy vectors. Pattern recognition is used to identify a fuzzy vector that represents the most likely causes of the crack.
Predicting the fire resistance behaviour of high strength concrete columns
(2004-02-01)
Kodur, VKR
;
Wang, TC
;
Cheng, FP
;
土木工程學系
;
Department of Civil Engineering
A numerical model, in the form of a computer program, for tracing the behaviour of high performance concrete (HPC) columns exposed to fire is presented. The three stages, associated with the thermal and structural analysis, for the calculation of fire resistance of columns are explained. A simplified approach is proposed to account for spalling under fire conditions. The use of the computer program for tracing the response of an HPC column from the initial pre-loading stage to collapse, due to fire, is demonstrated. The validity of the numerical model used in the program is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on HPC columns, together with results, are presented. The computer program can be used to predict the fire resistance of HPC columns for any value of the significant parameters, such as load, section dimensions, fiber reinforcement, column length, concrete strength, aggregate type, and fiber reinforcement. (C) 2003 Elsevier Ltd. All rights reserved.
Roles of non-structural walls in Chi-Chi Earthquake
(2002-07-01)
Liou, GS
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Chiu, YF
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Cheng, FP
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土木工程學系
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Department of Civil Engineering
Presented are some close observations of failure modes of building structures after the Chi-Chi Earthquake, which occurred on September 21, 1999, and some numerical analysis of building structures that proves the conclusions of these close observations. According to the observations and analysis results, one can conclude that non-structural walls play a major role in the damage and collapse of building structures in strong earthquakes. Therefore, some suggestions are made for the structural design industry and academic research in order to improve the earthquake resistance of existing and future building structures.
Stress-strain curves for high strength concrete at elevated temperatures
(2004-01-01)
Cheng, FP
;
Kodur, VKR
;
Wang, TC
;
土木工程學系
;
Department of Civil Engineering
The effects of high temperature on the strength and stress-strain relationship of high strength concrete (HSC) were investigated. Stress-strain curve tests were conducted at various temperatures (20, 100, 200, 400, 600, and 800degreesC) for four types of HSC. The variables considered in the experimental study included concrete strength, type of aggregate, and the addition of steel fibers. Results from stress-strain curve tests show that plain HSC exhibits brittle properties below 600degreesC, and ductility above 600degreesC. HSC with steel fibers exhibits ductility for temperatures over 400degreesC. The compressive strength of HSC decreases by about a quarter of its room temperature strength within the range of 100-400degreesC. The strength further decreases with the increase of temperature and reaches about a quarter of its initial strength at 800degreesC. The strain at peak loading increases with temperature, from 0.003 at room temperature to 0.02 at 800degreesC. Further, the increase in strains for carbonate aggregate HSC is larger than that for siliceous aggregate HSC.