Browsing by Author "Weng, CC"

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A strength superposition method for steel reinforced concrete (SRC) beam-column design
(1995)
Weng, CC
;
Yen, SI
;
交大名義發表
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National Chiao Tung University
A study on seismic pounding probability of buildings in Taipei metropolitan area
(2002-03-01)
Lin, JH
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
This study investigates the seismic pounding probability of buildings in the Taipei metropolitan area. Detailed procedures of the analytical method are presented. The results indicate that the building separation specified in the Seismic Provisions of the 1997 Taiwan Building Code (TBC'97) generally provides a relatively conservative estimate compared to that specified in the 19,94 Uniform Building Code (UBC'94) for the required distance to avoid pounding. This observation is demonstrated by comparing both the separation distance and/or the pounding probability of adjacent buildings based on the TBC'97 with those based on the UBC'94. The comparison results also reveal that the building separation distance specified by the TBC'97 is 1.6 times that specified by the UBC94 for the same building and site soil condition. If a reduction coefficient of 0.375 is adopted instead of the 0.6 specified in the TBC'97 to consider the effect of vibration phase difference of adjacent buildings, the critical pounding risk of the TBC'97 and the UBC'94 will be similar.
Comparisons of concrete-encased composite column strength provisions of ACI code and AISC specification
(2002-01-01)
Weng, CC
;
Yen, SI
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土木工程學系
;
Department of Civil Engineering
In the ACI-318 code (1999) and AISC-LRFD specification (1993), different approaches are used for the design of concrete-encased composite columns. The calculated member strengths based on these two design provisions may show significant difference in some cases. The objective of this study is to investigate the difference between these two approaches and to evaluate the accuracy of their strength predictions by comparing to 78 physical test results done by previous researchers. This comparative study indicates that the ACI-318 approach generally gives closer predictions than the AISC-LRFD does. The statistical results show that the ACI-to-experimental capacity ratio has a mean value of 0.90 with a coefficient of variation (COV) of 15% and the AISC-to-experimental capacity ratio has a mean value of 0.73 with a COV of 21%. Also investigated herein are the difference of design philosophy between the design provisions, the failure mode of the tested specimens, the column strength interaction diagram, and the effect of steel ratio on the accuracy of the strength predictions. (C) 2001 Elsevier Science Ltd. All rights reserved.
Enhanced electroluminescence of poly(2-methoxy-5-(2 '-ethylhexyloxy)-1, 4-phenylene vinylene) films in the presence of TiO2 nanocrystals
(2006-06-01)
Weng, CC
;
Chou, CH
;
Wei, KH
;
Huang, JY
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材料科學與工程學系
We demonstrated that in a nanocrystalline TiO2/poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) composite, electroluminescence of this composite is enhanced via addition of TiO2 nanoneedles. The TiO2 nanoneedles enhance the partial crystallization of MEH-PPV around TiO2, which in turn causes a decrease in the hole barrier height and an increase in hole mobility. The I-V measurement was established on an indium tin oxide/MEH-PPV:TiO2/Al device to identify the electrical properties of the composites.
Evaluation of dynamic vehicle load on bridge decks
(2004-09-01)
Lin, JH
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
Developed herein is a spectral approach for evaluating the dynamic vehicle load due to the passage of a vehicle moving at constant speed along a rough bridge surface. Based on the approach, a simple closed-form solution for predicting the variation of dynamic vehicle load on a bridge deck is derived. Numerical examples of the application of the solution to a simply-supported bridge are presented. Four different classes of pavement roughness (including: very good, good, average, and poor pavements) and three different vehicle speeds (speeds of 60, 100, and 140 km/h) are used in numerical analysis. The Dynamic Load Coefficient (DLC), a parameter used to characterize the magnitude of dynamic vehicle load, is estimated. The effects of vehicle speed and pavement roughness on the variation of dynamic vehicle load are investigated. It is concluded that if the effect of engine motion on vehicle vibration is disregarded, both the DLC and standard deviation of dynamic vehicle load are proportional to the square root of the pavement roughness coefficient S(no) for a specified vehicle speed.
Experimental behaviour and strength of concrete-encased composite beam-columns with T-shaped steel section under cyclic loading
(2005-07-01)
Chen, CC
;
Li, JM
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
Experimental research was conducted to investigate the structural behaviour of concrete-encased composite beam-columns with T-shaped steel section. Specimens were tested under lateral cyclic loading and axial compression. The test parameters included the distribution of longitudinal reinforcement, the spacing of transverse reinforcement, the presence of cross ties, and the axial compressive load level. The test results indicate that the cyclic behaviour and failure modes of the beam-columns are greatly affected by the direction of the bending moment owing to the unsymmetrical cross section. The concrete-encased composite beam-columns can develop stable hysteretic response and large energy absorption capacity by providing cross ties and decreased spacing of transverse ties. The current ACI and AISC-LRFD design provisions were also evaluated by comparing predicted strengths with the test results. (c) 2005 Elsevier Ltd. All rights reserved.
Experimental study on shear splitting failure of full-scale composite concrete encased steel beams
(2002-09-01)
Weng, CC
;
Yen, SI
;
Jiang, MH
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土木工程學系
;
Department of Civil Engineering
Presented herein is an experimental study that focuses on the shear splitting failure of composite concrete encased steel beams. Nine full-scale specimens were constructed and tested in this study. Significant horizontal cracks along the interface of steel flange and concrete, referred to as the shear splitting failure, appeared in five tested specimens. Observations from the experiments indicate that the steel flange width ratio, defined as the ratio of steel flange width to gross section width, has a dominant effect on the shear splitting failure of composite beams. The test results reveal that the shear splitting failure occurs when the steel flange width ratio of a composite beam reaches 0.67. The test results also show that the application of shear studs has a positive effect on preventing this type of failure for beams with large steel flange ratio. In addition to the experimental study, a new method for predicting the failure mode of composite beams is proposed. The proposed method gives satisfactory predictions as compared to the test results. Finally, a new equation is derived for the design of the stirrups to prevent shear splitting failure of naturally bonded composite beams.
Probability analysis of seismic pounding of adjacent buildings
(2001-10-01)
Lin, JH
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
The need to investigate the level of seismic pounding risk of buildings is apparent in future building code calibrations. In order to provide further insight into the pounding risk of adjacent buildings, this study develops a numerical simulation approach to estimate the seismic pounding risk of adjacent buildings separated by a minimum code-specified separation distance during a certain period of time. It has been demonstrated that the period ratio of adjacent buildings is an important parameter that affects the pounding risk of adjacent buildings. However, there is no specific consideration for the period ratio in the related seismic pounding provisions of the 1997 Uniform Building Code. Results also reveal that, for two adjacent buildings, the probability distribution of required distance to avoid seismic pounding fits very well with the type I extreme value distribution. Copyright (C) 2001 John Wiley & Sons, Ltd.
Selective distribution of surface-modified TiO2 nanoparticles in polystyrene-b-poly (methyl methacrylate) diblock copolymer
(2003-07-29)
Weng, CC
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Ordered aggregates of surfactant-modified TiO2 nanoparticles in the selective block of lamellar assemblies of the diblock copolymer PS-b-PMMA have been prepared. The hydrophobic or hydrophilic nature of the tethered surfactant determines the location of TiO2 nanoparticles in the corresponding block, as confirmed by transmission electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The modes of dispersion of TiO2 in the blocks depend on the type of bonding between the surfactant and TiO2. Photoluminescence studies of these nanocomposites demonstrate that the location of TiO2 nanoparticles affect the block copolymer's luminescence at different wavelengths.
Shear strength of concrete-encased composite structural members
(2001-10-01)
Weng, CC
;
Yen, SI
;
Chen, CC
;
土木工程學系
;
Department of Civil Engineering
This study investigates the shear strength of composite steel and concrete members in which the steel shape is fully encased in concrete. Two types of shear failure-diagonal shear and shear bond-are examined in this study. Through understanding of these failure modes, a new approach is proposed to predict the shear capacities of composite members. Major parameters investigated include steel flange width, shear reinforcement, concrete strength, and applied axial load. To evaluate the accuracy of the proposed approach, a verification analysis is made by comparing shear capacities predicted by the proposed approach with previous test results. Furthermore, the shear capacities predicted by the proposed approach are also compared with those obtained by American and Japanese provisions. The results of the analysis and comparison indicate that the proposed approach yields satisfactory prediction of shear strength and provides a rational explanation on the mechanism of shear bond failure. A new term, the critical steel flange ratio, is introduced to distinguish the shear bond failure from the conventional diagonal shear failure.
Simplified design approach for cold-formed stainless steel compression members subjected to flexural buckling
(2005-12-01)
Lin, SH
;
Yen, SI
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
The design criteria of stainless steel compression member are more complicated than those of carbon steels due to the nonlinear stress strain behavior of the material. In general, the tangent modulus theory is used for the design of cold-formed stainless steel columns. The modified Ramberg-Osgood equation given in the ASCE Standard can be used to determine the tangent modulus at specified level of stresses. However, it is often tedious and time-consuming to determine the column buckling stress because several iterations are usually needed in the calculation. This paper presents new formulations to simplify the determination of flexural buckling stress without iterative process. Taylor series expansion theory is utilized in the study for numerical approximations. The proposed design formulas are presented herein and can be alternatively used to calculate the flexural buckling stress for austenitic type of cold-formed stainless steel columns. It is shown that the column strengths determined by using the proposed design formulas have good agreement with those calculated by using the ASCE Standard Specification. A design example is also included in the paper for cold-formed stainless steel column designed by using the ASCE Standard equations and the proposed design formulas. (c) 2005 Elsevier Ltd. All rights reserved.
Spectral analysis on pounding probability of adjacent buildings
(2001-07-01)
Lin, JH
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
Presented herein is a spectral approach to evaluate the seismic pounding probability of two adjacent buildings simulated by multidegree-of-freedom systems and separated by a minimum code-specified separation during a period of time. The analytical approach is based on random vibration theory and total probability theory. Numerical simulations of 36 cases are presented in this study. Results of this investigation reveal that the period ratio of the adjacent buildings plays a major role that affects the pounding risk of adjacent buildings. Also noted is that the effect of period ratio on pounding risk has not yet been taken into account in the seismic pounding related provisions of the Uniform Buildings Code. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthesis of arrayed, TiO2 needlelike nanostructures via a polystyrene-block-poly(4-vinylpyridine) diblock copolymer template
(2004-10-19)
Weng, CC
;
Hsu, KF
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Wei, KH
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材料科學與工程學系
;
Department of Materials Science and Engineering
Arrayed, needlelike nanostructures of rutile phase crystal TiO2 were grown on a Si substrate containing TiO2 seeds prepared through a thin polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer template. The morphology of the deposited TiO2 nanostructures was characterized by field-emission scanning electron microscopy, X-ray diffraction, and transmission electron microscopy (TEM). By using TiO2 seeds prepared from their diblock copolymer PS-b-P4VP template, we fabricated arrayed, needlelike rutile TiO2 nanostructures with variable spatial positions and densities. The distance between two TiO2 needle bunches (120 and 160 nm) could be controlled using block copolymer templates with different molecular weights.
Using a solution crystal growth method to grow arrays of aligned, individually distinct, single-crystalline TiO2 nanoneedles within nanocavities
(2005-06-28)
Weng, CC
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Chen, CP
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Ting, CH
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Wei, KH
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材料科學與工程學系