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CONTENTS
Volume 10, Number 3, September 2000
 

Abstract
The effects of weight and axial inertia of a beam are taken into account for studying the nonlinear vibration of the Timoshenko beam due to external loads. The combination of Galerkins method and Runge-Kutta method are employed to obtain the dynamic responses of the beam. A concentrated force and a two-axle vehicle traversing on the beam are taken as two examples to investigate the response characteristics of the beam. Results show that the effect of axial inertia of the beam increases the fundamental period of the beam. Further, both the dynamic deflection and the dynamic moment of the beam obtained with including the effect of axial inertia of the beam are greater than those of the beam without including that effect of the beam.

Key Words
weight, axial inertia, period, vehicle, dynamic moment

Address
Wang RT, Natl Cheng Kung Univ, Dept Engn Sci, Tainan 70101, Taiwan
Natl Cheng Kung Univ, Dept Engn Sci, Tainan 70101, Taiwan

Abstract
A procedure has been developed for bolting steel plates to the sides of existing reinforced concrete beams which can be used to increase the shear strength of beams, increase the flexural strength of beams with enhanced ductility or with only a small loss of ductility, and increase the stiffness of beams in order to reduce deflections and crack widths. It will be shown in this paper, through a qualitative analysis and through the results of testing eight large scale beams, that standard rigid plastic analysis techniques which are commonly used in the design of reinforced-concrete, steel, and composite steel and concrete beams cannot be used directly to design composite bolted-plated reinforced-concrete beams. In the companion paper, quantitative procedures will be used to adapt the standard rigid plastic analysis techniques for this relatively new form of retrofitting.


Key Words
retrofitting, rehabilitation, composite, reinforced concrete, plated beams

Address
Ahmedt M, Univ Adelaide, Dept Civil & Environm Engn, Adelaide, SA 5005, Australia
Univ Adelaide, Dept Civil & Environm Engn, Adelaide, SA 5005, Australia
Univ New S Wales, Dept Struct Engn, Sydney, NSW 2052, Australia

Abstract
In a companion paper, tests on bolted side plated beams have shown that side plates can substantially increase the strength of existing reinforced concrete beams with little if any loss of ductility and, furthermore, induce a gradual mode of failure after commencement of concrete crushing. However, it was also shown that transverse interaction between the side plates and the reinforced concrete beam, that is vertical slip and which is a concept unique to side plated beams, is detrimental. Transverse interaction increases the forces on the bolt shear connectors and, hence, weakens the beam. It also reduces the ability of the composite plated beam to yield and, hence, to attain its full flexural capacity. The generic concept of transverse interaction will be described in this paper and the results used to develop a new form of rigid plastic analysis for bolted side plated beams which is illustrated with an application.


Key Words
retrofitting, rehabilitation, composite, reinforced concrete, plated beams, transverse interaction

Address
Oehlers DJ, Univ Adelaide, Dept Civil & Environm Engn, Adelaide, SA 5005, Australia
Univ Adelaide, Dept Civil & Environm Engn, Adelaide, SA 5005, Australia
Univ New S Wales, Dept Struct Engn, Sydney, NSW 2052, Australia

Abstract
The objective of this study is to analyze the deformational characteristics of a high-vacuum insulation panel that is evacuated to eliminate significant gas-phase conductance through its thickness. The panel is composed of a metal envelope and low thermal conductance spacers. The problem is very challenging because several nonlinearities are involved concurrently. Not only are various finite element models such as triangular, rectangular, beam and circular plate models used to simulate the panel, but also several finite element programs are used to solve the problem based on the characteristics of the finite element model. The numerical results indicate that the effect of the diameter of the spacer on the vertical deformation of the plate panel is negligibly small. The parameter that mainly influences the maximum sag is the spacing between the spacers. The maximum vertical deformation of the panel can be predicted for a practical range of the spacing between the spacers and the thickness of the plate. Compared with the numerical results obtained by the finite element models and the experimental tests, they have a good agreement. The results are represented in both tabular and graphical forms. In order to make the results useful, a curve fitting technique has been applied to predict the maximum deformation of the panel with various parameters. Moreover, the panel was suggested to be a \"smart\" structure based on thermal effect.

Key Words
characteristics, vacuum, insulation, panel

Address
Shu HS, Chinese Mil Acad, Dept Civil Engn, 1 Hwang Poo Rd, Feng Shan 83000, Taiwan
Chinese Mil Acad, Dept Civil Engn, Feng Shan 83000, Taiwan

Abstract
In this paper, a core wall structure coupled with connecting beams is discretized and modeled as an equivalent thin-walled member with closed section, while the connecting beams between openings are replaced by an equivalent shear diaphragm. Then, a numerical method (finite member element method, FMEM) for dynamic analysis of the core wall structure is proposed. The numerical method combines the advantages of the FMEM and Vlasov\'s thin-walled beam theory and the effects of torsion, warping and, especially, the shearing strains in the middle surface of the walls are considered. The results presented in this paper are very promising compared with the ones obtained from finite element method.

Key Words
thin-walled closed cross section, finite member element, warping, vibration

Address
Wang QF, Natl Huaqiao Univ, Dept Civil Engn, Quanzhou 362011, Fujian, Peoples R China
Natl Huaqiao Univ, Dept Civil Engn, Quanzhou 362011, Fujian, Peoples R China

Abstract
The present paper, deals with the dynamic analysis of a thin-walled tower with varying cross-section and additional masses. It, especially, deals with the effect of the rotary inertia of those masses, which have been neglected up to now. Using Galerkin\'s method, we can find the spectrum of the eigenfrequencies and, also, the shape functions. Finally, we can solve the equations of the problem of the forced vibrations, by using Carson-Laplace\'s transformation. Applying this method on a tall mast with 2 concentrated masses, we can examine the effect of the rotary inertia and the diaphragmatic operation of the above masses, on the 3 first eigenfrequencies.

Key Words
concentrated masses, thin-walled member, tall masts, rotary inertia, diaphragmatic operation

Address
Michaltsos GT, Natl Tech Univ Athens, Dept Civil Engn, 42 Patiss Str, GR-10682 Athens, Greece
Natl Tech Univ Athens, Dept Civil Engn, GR-10682 Athens, Greece

Abstract
Based on the two-dimensional constitutive relationship of the piezoelastic material, this paper derived an analytic solution to the elastic beam with the piezoelectric layer under the electric field, presented the explicit expressions of its displacement and stress. It is helpful for understanding the electrical and mechanical behavior of piezoelectric materials as actuators and the validation of the numerical methods such as FEM.

Key Words
piezoelastic, laminated beam, electric field, plane stress

Address
Lin QR, Shanghai Jiao Tong Univ, Dept Engn Mech, Shanghai 200030, Peoples R China
Shanghai Jiao Tong Univ, Dept Engn Mech, Shanghai 200030, Peoples R China

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