Showing papers on "Portal frame published in 1987"

Folding tent frame

Abstract: A foldable tent frame comprising tubular members 6, 7 and 8 linked by pivoting joints which enable the frame to be folded without the need for any mechanical disconnection of the tubular members from the joints. The joints may comprise two components 1, 2 which are pivotally interconnected and define when so interconnected three sockets for receiving the ends of tubular frame members 6, 7 and 8. The frame may comprise two end portal frames interconnected by horizontal non-folding side members, and at least one of the joints of each end portal frame may be spring-biased to a folded position, by springs 25.

Optimum design of reinforced concrete structures under variable loadings

Abstract: This paper presents a method for optimal design of reinforced concrete (RC) structures, subjected to quasi-static variable loads and accounting for cross-sections limited ductility requirements. It consists of a very simple refinement procedure to be applied in the classical Optimal Shakedown Design, (OSD), which leads to a strengthened structure satisfying the requisite that the actual plastic relative rotations, developed at a specified set of critical sections as a result of a variable repeated loading program, do not exceed given upper limits. This strengthened design is a safe but not strictly optimal design and is obtained using the simple rule that the steel reinforcement area at every critical section of the classical OSD must be increased by an amount which is inversely proportional to the correspondent relative rotation upper limit. A few examples illustrate the easiness of such a refinement procedure.

Moment Resisting Joints

Abstract: Walford constructed and tested a portal frame with nail fixed steel side plates in 1970 and demonstrated that such joints could be manufactured with similar stiffness to that of the surrounding timber and that failure invariably occurred in the timber members. This type of joint was adopted shortly after by Gibson for commercial application, with various tests being carried out to evaluate their performance and to prove viability to both himself and the local building authorities. The scope was expanded by Batchelar, the first Timber Engineering Research Fellow in 1980, incorporating plywood gusset plates to transfer the moment across the adjacent members. Simple empirical design rules for their construction were formulated from various tests carried out over a 3 year period. The Author has continued the investigation into these types of moment resisting joints by evaluating past tests and carrying out a series of experimental tests linked with the development of a computer model.

The Effect of Cracks on the Structural Strength of Beams and Portal Frames under Impact

Abstract: As a first stage into the study of the effect of cracks on the dynamic response of beams and portal frames, an elastic analysis is presented. The method combines dynamic photoelasticity with a computer program based on the finite difference formulation of the equations of elasticity. The method is compared to an analytical approach using the Timoshenko beam theory. It is concluded that a hybrid experimental/mathematical model is the most appropriate for practical purposes.

Multiple Bolt Row Moment End-Plates

Abstract: This paper presents a portion of the results of a study to develop design procedures for the extended, multiple row, moment end-plate configuration. This configuration is used in steel portal frame construction to connect a rafter to a rafter (a 'splice-plate connection') or to connect a rafter to a column. The objectives of the study were accomplished by developing end-plate strength prediction and bolt force prediction equations. Six tests of full size end-plate configurations were then performed to verify these analytical prediction equations.

Reinforced concrete portal frame

Abstract: Reinforced concrete portal frame consisting of three elements, two identical columns 1 support the element 2, assembling takes place by means of added elements This portal frame is particularly intended for industrial and commercial buildings