Showing papers on "Portal frame published in 2000"

Behaviour of reinforced concrete frames rehabilitated with concentric steel bracing

Abstract: The seismic performance of low-rise nonductile reinforced concrete (RC) buildings rehabilitated using con - centric steel bracing is investigated. A three-story building was analysed using various ground motion records. The ef - fectiveness of the steel bracing in rehabilitating the three-story building was examined. The effect of the distribution of the steel bracing along the height of the RC frames on the seismic performance of the rehabilitated building was stud- ied. The behaviour of the nonductile RC frame members is represented using a beam-column element capable of mod- elling the strength softening and the effects of the axial force on the yield moment and the deformation capacities at peak strength of these members. The performance of the building is evaluated in terms of global and story drifts and damage indices. A simplified approach is proposed for selecting the proper brace distribution.

Three-dimensional simulation of nonlinear response of reinforced concrete members subjected to impact loading

Abstract: A triaxial failure criterion was applied with the theory of plasticity to model the behavior of reinforced concrete structures subjected to impact loading The concrete nonlinearity, the cracking in the concrete elements, and the loading and unloading were simulated using an elastic-plastic fracture model The influence of the loading rate on the concrete can readily be introduced by modifying the level of the yield and loading surfaces if the necessary data are available In tension, a smeared crack model was used with a tension-softening model for the retained postcracking stresses The reinforcing bars were represented by tensile stiffeners that were smeared in the appropriate direction over the element cross section Verification of the analytical procedure was carried out using previously published results from scale model tests on a reinforced microconcrete beam and a portal frame, as well as from a test on a full-scale reinforced concrete beam It was found that the maximum impact load, the propagation of the cracks, and the failure modes can be predicted with reasonable accuracy using the proposed approach The approach can be used in the design of reinforced concrete structures subjected to impact loads

Effects of shear deformation on the effective length of tapered columns with I-section for steel portal frames

Abstract: Based on the stiffness equation of the tapered beam element involving the effects of axial force and shear deformation, numerical investigations are carried out on elastic instability for web-linearly tapered columns with I-section of steel portal frames. Effects of shear deformation on the effective length of the tapered columns with I-section are studied. An efficient approach for determining the effective length of the tapered portal frame columns considering effects of shear deformation is proposed.

Multi-function X-ray shielding lead screen for diagnosis

Abstract: The utility model relates to a special multi-function X-ray shielding lead screen for introductive diagnosis. A base seat with a walking wheel is provided with a portal frame with a square hole; a rotary screen is hinged on the portal frame. A slide screen is connected with a balancing body which is movably inlaid in a guild groove of the portal frame through a pulley mechanism connected with the portal frame, and automatically lifts. A lead glass viewing window is arranged on the slide screen; the lower edge of the slide screen is provided with a lead rubber hanging curtain with a semicircular hole to close gaps. A lighting lamp, a film viewing lamp and an interphone are also arranged on the portal frame. Shielding lead plates exist in each interlayer of the whole screen; consequently the whole screen forms a complete, radiated, isolating protective zone. The utility model has the advantages of convenient and flexible use and favorable shielding effect, and is capable of making the irradiation quantity and rate of X-rays decreased by 98.22 percents.

Development of LVL frame structures using glued metal plate joints II: strength properties and failure behavior under lateral loading.

Abstract: In past years high priority was given to developing a seismic design for wood structures, including research on the response of wood structures to earthquakes. In this study a new type of portal frame with relatively large span was developed for the traditional Japanese wooden houses with large openings at the front to strengthen the structure. Stainless steel plates coated with zinc and glued with epoxy adhesives on laminated veneer lumber (LVL) members, composed of Douglas fir veneer and bonded with phenolformaldehyde resin, were used. The connection between the frame's beam and columns and between the columns and groundsills was mechanical, with bolts. The subject of this research was to analyze strength properties and failure behavior of glued LVL metal joints used as structural components and to evaluate the response of LVL portal frames under cyclic lateral loading. The results show that portal frames using glued LVL metal plates have a good multiplier for the shear walls and may be applied to traditional Japanese structures. The equivalent viscous damping provided good energy dissipation in the frames. The joints displayed good mechanical behavior during tests; moreover, the structures demonstrated high strength, stiffness, and ductility, which are necessary for a seismic design.

Climbing method for climbing crane, and climbing crane

Abstract: PROBLEM TO BE SOLVED: To allow usage of a floor climbing method even when strength of a frame of the top floor is low, by temporarily fixing a lifting device for receiving repulsion of climbing to the floor on the top floor of a steel building, then lifting up a mast and a crane body, and fixing a base frame at the lower end of the mast to the floor of the top floor SOLUTION: This climbing crane 1 includes a portal frame 11 for ensuring height of a base frame 2 For lifting up the base frame 2 of this crane 1, a steel building work up to an acceptable floor height according to a certain mast height using a crane body 5 is first finished, and then a temporarily mounted support beam 10 is mounted onto the floor F of the top floor Next, the portal frame 11 is temporarily mounted onto the temporarily mounted support beam 10, and then a lifting device 4 is lifted down by a hydraulic cylinder and temporarily fixed to the portal frame 11 A mast 3 and the crane body 5 are lifted up by the lifting device 4, and the base frame 2 is lifted up to the floor F of the top floor and then fixed Then, the lifting device 4 is raised to the top of the mast 3 and the portal frame 11 is removed

Garage form and road width changing device for rod examination for automobile

Abstract: The utility model provides a garage form and road width changing device for rod examination for an automobile, which comprises a front and a back portal frames, a left and a right longitudinal guide rails, six rods and two road width lamps, wherein, the front portal frame is fixed on ground; the back portal frame is seated on the longitudinal guide rails; the centers of the front and the back portal frames are respectively fixed on one rod. The utility model is characterized in that the garage form and road width changing device for rod examination for an automobile also comprises two hoists, a left and a right inclined guide rails and A, B and C three rope series. The utility model can continuously and discretionally change the sizes of the garage form and the road width through a computer. The utility model not only can meet the need that a trainee uses the automobile which the trainee learns to drive to take the examination, but also can improve the utilization of a field.

Multifunctional mobile hydraulic bed

Abstract: The utility model provides a multifunctional mobile hydraulic bed, particularly suitable for correcting large and middle deformed workpieces. The utility model is composed of a main hydraulic system, an auxiliary hydraulic system, a portal frame, and a workbench. The main hydraulic system which is arranged on a top cross beam of the portal frame can transversally move. The auxiliary hydraulic system which is arranged on a lateral vertical column can rise and fall from top to bottom. The portal frame which is arranged on the workbench can longitudinally move. The workbench which is arranged on the ground can move. The top surface of a deformed workpiece can be corrected by the movement of the main hydraulic system and the portal frame. The lateral surface of the deformed workpiece can be corrected by the movement of the auxiliary hydraulic system and the portal frame. The utility model has the advantages of labor and time saving and good correcting quality.

Elevated portal frame

Abstract: The utility model belongs to a tool for vertical transport in middle or low or high constructions, particularly an elevated portal frame. The utility model is mainly characterized in that the utility model is mainly composed of a frame body, a cage, an attachment, a parking device, a capstan engine, super high and super low limiting devices, an overweight limiter, a signal connecting device, a visible system device, etc. The attachment is horizontally fixed to the frame body which is against one side of the building construction. The attachment is connected with the frame body by a fastener, and the parking device adopts a tool-type safe support and is positioned between two parallel support sections of the posts of the frame body. The capstan engine is provided with the super high and super low limiting devices. The elevated portal frame has the advantages of reasonable structural design and flexible and convenient operation so as to better satisfy the requirements of the construction site.