Peter J. Moss

FINITE ELEMENT ANALYSIS OF LAMINATED SHELLS OF REVOLUTION WITH LAMINATED STIFFENERS

Abstract A finite element analysis of orthogonally stiffened shells of revolution has been presented by combining a recently proposed shell of revolution element and a curved beam element. These two elements are isoparametric elements in which the effects of shear deformation and rotary inertia have been taken into account. They are meant to be used for arbitrarily laminated structures and are based on the higher-order theories presented recently by Bhimaraddi for plates, shells and beams.

Generalized finite element analysis of laminated curved beams with constant curvature

Abstract A 24-dofisoparametric finite element has been presented for the analysis of generally laminated curved beams. The effects of shear deformation and rotary inertia have been accounted for using the shear deformation theory which employs nonlinear shear strain variation across the section. Thus it is not necessary to specify the shear correction factors in the present element. The torsional response has been incorporated according to the elementary theory of torsion. It is shown that for certain unsymmetrically laminated curved beams the in-plane and out-of-plane motions are coupled. The numerical results presented illustrate the performance of the element and the effect of coupling.

A shear deformable finite element for the analysis of general shells of revolution

A 64-dof isoparametric quadrilateral finite element is presented for the analysis of generally laminated shells of revolution. The effects of shear deformation and rotary inertia are accounted for by using shear deformation theory that employs the parabolic shear strain variation across the thickness. The classical thin shell theory is the special case of shear deformation theory used in the present study. Thus, the thin shell element also can be obtained from the present thick shell element by simply having the displacement parameters (u1 and v1,) associated with the shear rotations as zeros. The numerical results presented illustrate the performance of the element and the effects of shear deformation.

The Behavior of Bearings Used for Seismic Isolation under Shear and Axial Load

The investigation described in this paper looked at both laminated elastomeric bearings and lead-rubber bearings in order to obtain a better understanding of the real bearing behavior under the combined action of shear and axial loads when used in a seismic-isolation system. In particular, the investigation focused on the distributions of vertical pressure on the bearing faces and the degree of lift-off of the edges of the bearings as the shearing displacement and the angle of rotation increased.

Compression behaviour of bridge bearings used for seismic isolation

A large number of seismic isolation systems have been developed since the early 1970s. They are basically a combination of elastomeric bearings and energy dissipators. Elastomeric bearings can lengthen the period of free vibration of a structure and play an important part in seismic isolation systems. As bridge bearings they have been investigated since 1940, but now they are being used in conjunction with lead plugs that can provide hysteretic damping and energy dissipation. The investigation described in this paper looked at both laminated elastomeric bearings and lead-rubber bearings in order to obtain a better understanding of the real bearing behaviour under compression load when used in a seismic-isolation system. In particular, the investigation focused on the vertical pressure distributions on the bearing faces and the prediction of compressive stiffness according to current design codes.

DEVELOPMENT OF A DESIGN PROCEDURE FOR BRIDGES ON LEAD-RUBBER BEARINGS

Abstract This paper presents a design method that is based on a parametric study of the response of bridge superstructures supported on lead-rubber bearings and subjected to El Centro 1940 N/S component and the 1966 Parkfield earthquakes. The effect of parameters such as lead plug sizes and aspect ratio, bearing thickness and yield strength, pier, abutment and superstructure stiffnesses, and different earthquake records, were investigated. Questions addressed included ‘when should lead-rubber bearings be used?’ and ‘can they be used to redistribute seismic forces between piers and abutments?’. The results of the time-history analyses answered these questions and showed clear trends. These are used in the design procedure, which the authors believe to be more straight-forward and conceptually clearer than the present design procedures.

Design of Timber-Concrete Composite Floors for Fire Resistance

This research investigated the fire performance and failure behaviour of timber-concrete composite floor systems currently under development in New Zealand, resulting in a design method for evaluating the fire resistance of these floors with different types of connections. Furnace tests were performed on two full-size floor specimens at the Building Research Association of New Zealand (BRANZ). Both floor specimens were 4 m long and 3 m wide, consisting of 65 mm concrete topping on plywood formwork, connected to double LVL (laminated veneer lumber) floor joists. They were tested over a 4 m span, subjected to a nominal design live load of 2.5 kPa. Both floors were subjected to the ISO 834 test fire for over 60 minutes. Two separate connection types were tested; concrete notches cut into the timber beams with an incorporated shear key, and metal toothed plates pressed between the double beams.It was found that the reduction in section of the timber beams due to the fire governed the failure mode of the floor...

Numerical and Experimental Evaluation of the Temperature Distribution Within Laminated Veneer Lumber (LVL) Exposed to Fire

The fire resistance evaluation of a timber member is an important and complex problem of structural design. In order to solve this problem, it is crucial to have reliable information on the temperature distribution within a timber cross-section exposed to fire, and to develop a numerical model for the prediction of such a quantity. The paper reports the experimental-numerical comparisons in terms of temperature distribution within a timber member made from radiata pine LVL (laminated veneer lumber) exposed to fire. The experimental tests were performed at the University of Canterbury and BRANZ (New Zealand) on 146×60, 300×105 and 360×133 mm LVL members. The temperature distribution was monitored using several thermocouples. The numerical results were obtained using the Abaqus FE code with different conductive models. The Eurocode 5 and Frangis proposals led to similar results characterized by acceptable approximation close to the surface. Since the accuracy reduced for deeper fibres, a new proposal based...

SOME TEXTILE APPLICATIONS OF FINITE-ELEMENT ANALYSIS. PART II: FINITE ELEMENTS FOR YARN MECHANICS

The concepts of modal decomposition developed in an earlier paper are used to produce a three-dimensional element for aligned fibre assemblies. The element degrees of freedom are introduced and the chosen mode shapes of the element demonstrated. The finite element is tested by using simple material-property assumptions, and the element is verified against a theoretical model of the twisting of a single fibre about a solid core. The element is then verified qualitatively by modelling realistic yarn situations, and the resultant deformation plots are presented.

Light Timber-Framed Walls Exposed to Compartment Fires

The objective of this project was to determine the equivalent time of exposure (to the ISO-834 standard fire), for a number of light timber-framed wall assemblies exposed to a range of time temperature curves characteristic of compartment fires.This analysis considered only the thermal behavior of the walls. Load bearing performance will be the subject of the next phase of the study.The overall method was as follows.(1) The data from four full-scale ISO-834 wall tests were used to calibrate a finite element model of the wall assembly developed using the TASEF program. Subsequently the model was validated using test on walls with different layouts.(2) A set of characteristic time-temperature curves for compartment fires was developed using the computer program COMPF-2, a post-flashover compartment fire model.(3) The finite element models of the walls developed in Step 1 were subjected to the time temperature curves developed in Step 2.(4) The temperatures within the wall assembly found in Step 3 were compa...