Abstract
The concept of the seismic slit shear wall was proposed in the early 1990
Key Words
shear wall; macroscopic model; energy dissipation; hysteretic model; cyclic loading.
Address
Huanjun Jiang and Xilin Lu ; Research Institute of Structural Engineering and Disaster Reduction, Tongji University, 1239 Siping Road, Shanghai, P.R. China A. K. H. Kwan and Y. K. Cheung; Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
Abstract
Local reinforcement in dowel type timber joints is essential to improve ductility, to increase load carrying capacity and to reduce the risk of brittle failure, especially in the case of using solid dowel. In many types of reinforcing materials available today, DVW (densified veneer wood) has been demonstrated to be the most advantages in terms of compatibility, embedding performance and ductility. Preliminary studies show that using appropriately sized DVW discs bonded into the timber interfaces may be an effective way to reinforce the connection. In this paper, non-linear 3-dimensional finite element models, incorporating orthotropic and non-linear material behaviour, have been developed to simulate structural performance of the timber joints locally reinforced by DVW discs. Different contact algorithms were applied to simulate contact conditions in the joints. The models were validated by the corresponding structural tests. Correlation between the experimental results and the finite element simulations is reasonably good. Using validated finite element models, parametric studies were undertaken to investigate effects of the DVW disc sizes and the end distances on shear stresses and normal stresses in a possible failure plane in the joint.
Key Words
DVW; local reinforcement; timber joint; finite element; parametric study; end distance.
Address
Structural Timber Research Unit, University of Brighton, Brighton BN2 4GJ, U.K.
Abstract
Scaled brick masonry panels were tested under cyclic unialxial compression loading to evaluate its deformation characteristics. An envelope stress - strain curves, a common point curves and stability point curves were obtained for various cyclic test conditions. Loops of the stress-strain hysteresis were used to determine the energy dissipation for each cycle. Empirical expressions were proposed for the relations between energy dissipation and envelope and residual strains. These relations indicated that the decay of masonry strength starts at about two-third of peak stress.
Key Words
brick; uniaxial; envelope curve; common point; stability point; cyclic loading; Stress-Strain Hysteresis; energy dissipation; envelope strain; plastic strain.
Address
Department of Civil Engineering, Indian Institute of Technology, Delhi - 110016, India
Abstract
Arbitrary Lagrangian Eulerian finite element methods gain interest for the capability to control mesh geometry independently from material geometry, the ALE methods are used to create a new undistorted mesh for the fluid domain. In this paper we use the ALE technique to solve fuel slosh problem. Fuel slosh is an important design consideration not only for the fuel tank, but also for the structure supporting the fuel tank.
Key Words
ALE; sloshing; multi-material formulation.
Address
N. Aquelet and M. Souli ; Universit?de Lille, Laboratoire de M?anique de Lille, CNRS 1441, Bd Paul Langevin Villeneuve d
Abstract
This paper investigates the structural behavior of modular falsework system under sequential pattern loads. Based on the studies of 25 construction sites, the pattern load sequence modeling is defined as models R (rectangle), L and U. The study focuses on the system critical loads, regions of largest reaction forces, discrepancy between the pattern load and the uniform load, and the warning-system plan. The analysis results show that the critical loads of modular falsework systems with sequential pattern loads are very close to those with the uniform load used in design. The regions of largest reaction forces are smaller than those calculated by the uniform load. However, the regions of largest reaction forces of three models under sequential pattern loads can be considered as the crucial positions of warning-system based on the measured index of loading. The positions of the sensors for the warning-system for these three different models are not identical.
Address
Jui-Lin Peng; Department of Construction Engineering, Yunlin University of Science and Technology, Yunlin, 640, Taiwan, R.O.C. Cheng-Lung Wu; Department of Construction Engineering, Chaoyang University of Technology, Taichung, 413, Taiwan, R.O.C. Siu-Lai Chan; Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hong Kong, China
Abstract
The primary aim of this study was to investigate the bond strength between reinforcement and concrete. Large sized nine beams, which were produced from concrete with approximately fc\' = 30 MPa, were tested. Each beam was designed to include two bars in tension, spliced at the center of the span. The splice length was selected so that bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. In all experiments, the variable used was the reinforcing bar diameter. In the experiments, beam specimens were loaded in positive bending with the splice in a constant moment region. In consequence, as the bar diameter increased, bond strength and ductility reduced but, however, the stiffnesses of the beams (resistance to deflection) increased. Morever, a empirical equation was obtained to calculate the bond strength of reinforcement and this equation was compared with Orangun et al. (1977) and Esfahani and Rangan (1998). There was a good agreement between the values computed from the predictive equation and those computed from equations of Orangun et al. (1977) and Esfahani and Rangan (1998).
Key Words
beams; bond of reinforcing bar-concrete; deformed bar; bending; splice length.
Abstract
Non-conforming membrane elements which have variable number of mid-side nodes with drilling degrees of freedom and which is designated as NMDx have been presented in this paper. The non-conforming elements with variable number of mid-side nodes can be efficiently used in the local mesh refinement for the in-plane structures. To guarantee the developed elements always pass the patch test, the direct modification method is incorporated into the element formulation. Detailed numerical tests in this study show the validity of the variable node NC elements developed in this study and a wide applicability of these elements to practical problems.
Key Words
direct modification method; drilling degrees of freedom; membrane element; transition element; variable node.
Address
Chang-Koon Choi; Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea Tae-Yeol Lee; Department of Civil and Environmental Engineering, University of California, Los Angeles, CA90095, USA
Abstract
Attempts at improving beam-column joint performance has resulted in non-conventional ways of reinforcement such as the use of the crossed inclined bars in the joint area. Despite the wide accumulation of test data, the influence of the crossed inclined bars on the shear strength of the cyclically loaded exterior beam-column joints has not yet been quantified and incorporated into code recommendations. In this study, the investigation of joints has been pursued on two different fronts. In the first approach, the parameters that influence the behaviour of the cyclically loaded beam-column joints are investigated. Several parametric studies are carried out to explore the shear resisting mechanisms of cyclically loaded beam-column joints using an experimental database consisting of a large number of joint tests. In the second approach, the mechanical behaviour of joints is investigated and the equations for the principal tensile strain and the average shear stress are derived from joint mechanics. It is apparent that the predictions of these two approaches agree well with each other. A design equation that predicts the shear strength of the cyclically loaded exterior beam-column joints is proposed. The design equation proposed has three major differences from the previously suggested design equations. First, the influence of the bond conditions on the joint shear strength is considered. Second, the equation takes the influence of the shear transfer mechanisms of the crossed inclined bars into account and, third, the equation is applicable on joints with high concrete cylinder strength. The proposed equation is compared with the predictions of the other design equations. It is apparent that the proposed design equation predicts the joint shear strength accurately and is an improvement on the existing code recommendations.
Key Words
mechanical behaviour; deformation; earthquake resistant structures; crossed inclined bars; cyclic loads; joints; shear properties; strut and tie models; anchorage; bond (concrete to reinforcement); beams; columns; reinforced concrete; connections; structural analysis; shear strength.
Address
Faculty of Civil Engineering, Istanbul Technical University, Maslak 80626, Istanbul, Turkey
