Showing papers on "Portal frame published in 1996"

Softening-Induced Dynamic Localization Instability: Seismic Damage in Frames

Abstract: This paper analyzes dynamic localization of damage in structures with softening inelastic hinges and studies implications for the seismic response of reinforced concrete or steel frames of buildings or bridges. First, the theory of limit points and bifurcation of the symmetric equilibrium path due to localization of softening damage is reviewed. It is proven that, near the state of static bifurcation or near the static limit point, the primary (symmetric) path of dynamic response or periodic response temporarily develops Liapunov-type dynamic instability such that imperfections representing deviations from the primary path grow exponentially or linearly while damage in the frame localizes into fewer softening hinges. The implication for seismic loading is that the kinetic energy of the structure must be absorbed by fewer hinges, which means faster collapse. The dynamic localizations are demonstrated by exact analytical solutions of torsional rotation of the floor of a symmetric and symmetrically excited frame, and of horizontal shear excitation of a building column. Static bifurcations with localization are also demonstrated for a portal frame, a multibay frame, and a multibay-multistory frame. The widely used simplification of a structure as a single-degree-of-freedom oscillator becomes invalid after the static bifurcation state is passed.

Modal characteristics of structural portal frames made of mechanically joined pultruded flat hybrid composites

Abstract: The primary objective of this investigation is to analyze and compare the dynamic behavior of framed structures made of orthotropic materials manufactured by the pultrusion process. Pultruded flat beams made of glass/epoxy, graphite/epoxy and various lay-up combinations of hybrid glass-graphite/epoxy are used to produce high-modulus and lightweight, L-shaped, portal frame and other composite material structures. The dynamic properties of the decoupled and mechanically fastened coupled structures were obtained by the experimental modal analysis technique. The structural properties identification process for each of the beam and lumped systems consists of generating the frequency response functions (FRF), estimation of natural frequencies, damping, and the associated mode shapes. A measurement chain comprising a dual-channel dynamic signal analyzer, corresponding instruments and a modal analysis software package has been used for identifying the modal parameters. The experimental results demonstrate the applicability and dynamic superiority of structures made with pultruded hybrid composite materials.

Plastic Design to BS 5950

Abstract: Introduction Principles of plastic design Further considerations in plastic design Plastic design of beams Pitched roof portal frame building Multi--storey buidings Miscellaneous portals Multi--span portal frames Design of agricultural buildings Performance of agricultural buildings Two case studies

Adjustable T-shape belt damper for coal conveyer

Abstract: The utility model relates to an adjustable transferring buffering coal blocking plate with a T-shaped belt. The utility model is a coal blocking device for the T-shaped transferring position of belt conveyers. The utility model is composed of a portal frame and a lower supporting frame. A buffering coal blocking plate facing the upper belt is fixed on the cross beam of the portal frame, and adjustable coal blocking plates are arranged on both sides of the portal frame. A coal blocking cylinder is arranged between the buffering coal blocking plate and the lower belt. The buffering coal blocking plate can be longitudinally and laterally adjusted on the cross beam and the portal frame, the angle can be adjusted by the adjustable coal blocking plates, and the portal frame can be longitudinally and laterally adjusted on the supporting frame. The utility model can solve the problems such as belt bruising, carrying material piling, transport line blocking, etc.

Awning device in ship

Abstract: PURPOSE:To easily perform extending and storing an awning by providing a rope fixing means of fixing one side of a rope in one end portal frame side, and providing a winding device for unwinding and for rewinding the other side of the rope in the other end portal frame side. CONSTITUTION:In the case of extending awnings S1 to S4, a winding device 12 is driven to draw out a rope 10 also to pull one end portal frames F1 to F4, and when this portal frame is moved on a rail through a roller, the awnings S1 to S4, while suspended to a hoist device 19, are extended between the one end and the other end portal frames F1 to F4. One side of the rope 10 is fixed to a turn buckle 11 molted a on a beam upper end part of the fourth portal frame F4, to wind the other side of the rope 10 to a winding drum 27 of the winding device 12 provided in a rear wall 4.

Box-type shed on vehicle

Abstract: The utility model relates to a box shed on an automobile in a flexible wing type, which relates to a guarding device for automobile transport The utility model is composed of a shed cloth (5), the frame (4) of the shed cloth, a portal frame (3), a framework (2) and a frame lifting device, wherein, the framework (2) and the portal frame (3) are connected as is showed in the picture, and are connected with the bottom board (1) of the carriage of the automobile; the frame lifting device is composed of an air cylinder (6) and a transmission mechanism (7), and the air cylinder (6) is hinged with the portal frame (3) The transmission mechanism (7) is suspended on the framework (2) through a ball bearing, and the both ends are respectively hinged with the air cylinder (6) and the frame (4) of the shed cloth The utility model has the advantages of simple structure, low cost and little possibility of deformation, and is simple and practical to be arranged on the existing automobiles

Distribution frame for high desity optical fiber

Abstract: The utility model relates to a distribution frame for high density optical fibers, a portal frame is arranged on a socket, and an upper, a middle and a lower cabling rails are arranged on the portal frame. Couples of thread rings and junction boxes are fixed on the left and the right frames of the portal frame, and the junction box is provided with a wire containing device besides a wire connecting device. The utility model solves the problems of complicated distributing frame structure, inconvenient wire containing operation and insufficient use of the space of the distribution frame which exist in traditional junction boxes which are separately allocated with the wire containing boxes. The utility model can establish a high density communication network of optical fiber lines which is 504 path at the most.

Gripper-type rope-break protection device for portal frame

Abstract: The utility model relates to a gripper-type rope-break protection device for portal frames, comprising a beam channel, a frame seat, a spring circular seat frame, a spring, a clamp friction brake, a sliding rocker sensing mechanism, etc., wherein, the clamp friction brake is composed of a clamp seat, a clamp, a cover plate and a stay bolt; the sliding rocker sensing mechanism is composed of an expanding wheel, a support frame, a support frame seat, etc., one end is connected with the upper end of the clamp, and the other end is fixed with the spring circular seat frame through a core axle; screws with flower bolts and oil ropes are arranged between the spring circular seat frame and the support frame and fastened into a whole body. The utility model has the advantages of simple structure and high safety and can be matched with a portal frame.