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CONTENTS
Volume 13, Number 1, January 2002
 

Abstract
This paper presents the findings of an investigation carried out to determine the most
appropriate connections, in terms of rotational stiffness, to use for the optimum design of cold-formed Zed
section sleeve joint purlin system. Experiments and parametric studies were conducted to investigate the
effects of geometric variables on the behavior of the sleeve-purlin and cleat-purlin connections of the
sleeve joint purlin system. The variables considered were purlin size and thickness, sleeve size, thickness,
length and bolt position. The test results were used to verify the empirical expressions, developed herein,
employed to determine the rotational stiffness of connections. With the predicted connection stiffness, the
most suitable sleeve-purlin and cleat-purlin connections can be selected so as to produce an optimum
condition for the sleeve joint purlin system.


Key Words
connection; cleat-purlin; cold-formed; joint; optimum design; purlin; rotational stiffness;

Address
School of Mechanical & Production Engineering,
Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore


Abstract
The use of local two-sided and three-sided jacketing for the repair and strengthening of reinforced concrete beam-column joints damaged by severe earthquakes is investigated experimentally and analytically. Two exterior beam-column joint specimens (O-1 and O-2) were submitted to a series of cyclic lateral loads to simulate severe earthquake damage. The specimens were typical of existing older structures built in the 1960s and 1970s. The specimens were then repaired and strengthened by local two-sided or three-sided jacketing according to UNIDO Manual guidelines. The strengthened specimens (RO1 and RO2) were then subjected to the same displacement history as that imposed on the original specimens. The repaired and strengthened specimens exhibited significantly higher strength, stiffness and better energy dissipation capacity than the original specimens.

Key Words
beams (supports), buildings, columns (supports), damage, earthquake resistant structures, joints (junctions), lateral pressure, load (forces), reinforced concrete, repairs, shear properties, cement grout, strengthening

Address
Tsonos AG, Aristotelian Univ Thessaloniki, Div Struct Engn, POB 482, GR-54006 Thessaloniki, Greece
Aristotelian Univ Thessaloniki, Div Struct Engn, GR-54006 Thessaloniki, Greece

Abstract
It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method)

Key Words
shakedown analysis; incremental collapse; earthquake load, plastic hinge; nonlinear programming

Address
Department of Architectural Engineering, Korea university ,Seoul 136-701, Korea

Abstract
Composites exhibit larger dispersion in their material properties compared to conventional materials due to larger number of parameters associated with their manufacturing processes. A C-0 finite element method has been used for arriving at an eigenvalue problem using higher order shear deformation theory for initial buckling of laminated composite plates. The material properties have been modeled as basic random variables. A mean-centered first order perturbation technique has been used to find the probabilistic characteristics of the buckling loads with different edge conditions. Results have been compared with Monte Carlo simulation, and those available in literature.

Key Words
finite element method, random variables, buckling, probabilistic characteristics, composite plates, vivbration analysis

Address
Singh BN, Indian Inst Technol, Dept Aerosp Engn, Kanpur 208016, Uttar Pradesh, India
Indian Inst Technol, Dept Aerosp Engn, Kanpur 208016, Uttar Pradesh, India

Abstract
Many existing concrete structures suffer from low quality of concrete and inadequate confinement reinforcement. These deficiencies cause low strength and ductility. Wrapping concrete by carbon fiber reinforced polymer (CFRP) composite sheets enhances compressive strength and deformability. In this study, the effects of the thickness of the CFRP composite wraps on the behavior of concrete are investigated experimentally. Both monotonic and repeated compressive loads are considered during the tests, which are carried out on strengthened undamaged specimens, as well as the specimens, which were tested and damaged priorly and strengthened after repairing. The experimental data shows that, external confinement of concrete by CFRP composite sheets improves both compressive strength and deformability of concrete significantly as a function of the thickness of the CFRP composite wraps around concrete. Empirical equations are also proposed for compressive strength and ultimate axial deformation of FRP composite wrapped concrete. Test results available in the literature, as well as the experimental results presented in this paper, are compared with the analytical results predicted by the proposed equations.

Key Words
columns (supports), confined concrete, ductility, strength, fibers, stress-strain curves

Address
Ilki A, Istanbul Tech Univ, Fac Civil Engn, Struct & Earthquake Engn Lab, TR-80626 Istanbul, Turkey
Istanbul Tech Univ, Fac Civil Engn, Struct & Earthquake Engn Lab, TR-80626 Istanbul, Turkey
Istanbul Tech Univ, Fac Civil Engn, Reinforced Concrete Div, TR-80626 Istanbul, Turkey

Abstract
During the last several years, research activity on non-tubular bonded joints has concentrated on the effects of normal stress, bending moments and shear. Nevertheless, in certain situations, the structure may be subjected to twisting moments, so that the evaluation of its dynamic behaviour to torsional vibrations becomes of great importance even though evaluations of such loading conditions is entirely lacking in the literature. The aim of this article is to show that torsional natural frequencies of the non-tubular joint can be evaluated by determining the roots of a determinantal equation, derived by taking advantage of some analytical results obtained in a previous paper dealing with the analysis of the state of stress in the adhesive. Numerical results related to clamped-free and clamped-clamped joints complete the article.

Key Words
bonded joint, dynamic properties, torsional oscillation

Address
Pugno N, Politecn Turin, Dept Struct & Geotech Engn, Corso Duca Abruzzi 24, Turin, Italy
Politecn Turin, Dept Struct & Geotech Engn, Turin, Italy
Politecn Turin, Dept Aeronaut & Space Engn, Turin, Italy

Abstract
A solution based on the linear three-dimensional theory of elasticity is developed for vibration and elastostatic problems of hollow toroids. The theory is developed for transversely isotropic toroids of arbitrary thickness, and has the potential to validate some vehicle and aircraft tire models in the linear range. In the semi-analytical method that is adopted Fourier series are written in the circumferential direction, forming a set of two-dimensional problems. These problems are solved using the differential quadrature method. A commercial finite element program is used to determine alternative solutions. For validation both problems of vibration and elastostatics are considered. Finally results are determined for local surface loading problems, and conclusions are drawn.

Key Words
toroids, differential quadrature, finite elements

Address
Univ Ottawa, Dept Mech Engn, Ottawa, ON K1N 6N5, Canada


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