Showing papers on "Portal frame published in 2005"

On Saturation Control of a Non-Ideal Vibrating Portal Frame Foundation Type Shear-Building

Abstract: In this paper, we examine the nonlinear control method based on the saturation phenomenon and of systems coupled with quadratic nonlinear ties applied to a shear-building portal plane frame foundat...

Advanced Analysis of Imperfect Portal Frames with Semirigid Base Connections

Abstract: A robust finite element procedure for large deflection and inelastic analysis of imperfect steel frames with semirigid base is proposed and the nonlinear behavior of semirigid frames with various modes of initial imperfection is studied. Special consideration to the method of simulating the frame initial imperfections is given. The refined plastic hinge method is used for modeling of the section plastification and both the notional force and the initially imperfect geometry of the frames obtained by an eigenvalue buckling analysis are used for modeling the geometrical imperfections. The difference between the notional force and the eigenbuckling mode models and of semirigid base connections are studied. From the examples reported in this paper, the effective length is not required to be assumed and the advanced analysis is noted to be applicable to practical design of this type of steel frames.

Simulated Annealing Optimization Of Walls,Portal And Box Reinforced ConcreteRoad Structures

Abstract: This paper deals with the economic optimization of reinforced concrete walls, portal and box frame structures typically used in road construction. It shows the efficiency of heuristic optimization by the simulated annealing algorithm. The evaluation of solutions follows the Spanish Code for structural concrete. Stress resultants and envelopes of framed structures are computed by an external finite element program. Design loads are in accordance with the national IAP Code for road bridges. The algorithm is first applied to RC retaining walls with 26 continuous design variables of geometry, materials and reinforcement. Results on this topic show the importance of limiting the deflection of walls. No restriction leads to slender solutions with deflections of up to 1/40 the height of the wall. Such elements are unfeasible and, hence, a limitation of 1/150 of the height is adopted for the design of these structures. The second structure analysed is a 10 m horizontal span RC portal frame. This example has 28 discrete variables, 5 geometrical, 3 types of concrete and 20 types of reinforcement bars of fixed length. The evaluation module includes the limit states that are commonly checked in design: flexure, shear, deflections, etc. Results of this research are again quite slender, i.e. a slab of 0.375 m (1/26.67 slab/span ratio), not complying with the rarely checked fatigue of concrete. The last type of structure analysed is a 13 m horizontal span RC box road frame. This example has 44 discrete variables, 2 geometrical, 2 types of concrete and 40 reinforcement bars and bar lengths. The evaluation module includes fatigue plus other limit states. Results are now reasonably slender, i.e. a slab of 0.65 m (1/20 slab/span ratio). Finally, run times indicate that heuristic optimization is a forthcoming option for the design of real RC structures.

A conforming unified finite element formulation for the vibration of thick beams and frames

Abstract: Beams and frames are common features in many engineering structures and in this paper an approach is given to model their dynamic behaviour adequately. Whilst the eigen-frequencies of continuous systems comprising of slender beams can be identified, in most cases of practical interest, by means of Euler or Timoshenko beam theory, for structures comprising of thick beam models this is not necessarily true since such idealizations constrain the cross-sections to remain planar. This paper suggests an alternative approach by means of a unified fully conforming plane stress rectangular finite element which is believed to allow for more realistic representation of the shear effects and hence the strain field around the joints of such structures. The usefulness and functionality of this improved numerical approach is explored via comparison against a non-conforming two-dimensional plate as well as one-dimensional Euler–Bernoulli and Timoshenko finite element formulations corresponding to a variety of beam aspect ratios representing the structures of a rotor and a portal frame. The idealization is shown to be particularly advantageous for simulating the effects of shear distortion where beams join at right angles and the transverse forces in one member interact with the extensional forces of the adjoining structure. Copyright © 2004 John Wiley & Sons, Ltd.

Multifunctional rehabilitation vehicles

Abstract: The utility model discloses a multifunctional rehabilitation vehicle, belonging to the technical field of equipment which helps the ill and the disabled rehabilitate, which provides a convenient-to-use multifunctional rehabilitation vehicle, and which is favorable for the patient to do rehabilitation exercise independently, to improve the rehabilitation effect and to alleviate burdens on the nursing staff. The utility model comprises a vehicle frame and a walking wheel; the vehicle frame is composed of an upper frame, a middle frame, a lower frame and a vertical supporter, and the back ends of the upper frame and the lower frame are respectively provided with a horizontal supporter; the upper frame is provided with a tabletop, a safety belt, a hanging ring, a fixing frame and a double-stick which is fixed on the upper frame, and the middle frame is provided with a base plate which is movably connected with the middle frame; the lower frame is provided with a chain wheel which is connected with two pedals, and the walking wheel is arranged on the lower frame; the front end of the vehicle frame is provided with a portal frame whose cross beam is a crankshaft, and the crankshaft is fixedly provided with a small chain wheel; a traction rope is tied to the crank lever of the crankshaft, and a close transmission chain is arranged between the small chain wheel and the chain wheel on the lower frame. Structures which are easy to assemble and disassemble or movable structures are mostly adopted to be the members thereof, and the utility model, which is safe and practical, alleviates burdens on the nursing staff greatly, particularly suitable for hemiplegia sufferers to exercise and rehabilitate.

Movable spray-painting room

Abstract: The utility model relates to a movable paint spraying chamber, which belongs to the improvement on a paint spraying apparatus. For solving such a problem, the utility model provides the movable paint spraying chamber which has the advantages of simple structure and no environment pollution. The utility model comprises a portal frame (4) which is structurally characterized in that a roller wheel (3) arranged on the bottom of the portal frame (4) is connected with a motor (2), an operating platform (9) is arranged above the portal frame (4), both sides of the portal frame (4) are respectively provided with elevating operating boxes (5) with inward openings (7), both sides of the elevating operating boxes (5) are provided with air outlets (17), chain wheels (13) of the elevating operating boxes (5) are connected with chains (14) of the portal frame (4), the top parts of the elevating operating boxes (5) are connected with an expansive type air discharge pipe (8) which is provided with an air outlet machine (10), and both sides of the top part of the portal frame (4) are respectively provided with air inlet machines (11).

Tunnel Car Wash

Abstract: The invention concerns a tunnel car wash comprising a wetting entry (E) and a pre-wash arch (A1), a high pressure portal frame (P2), one or several roller-equipped portal frames (P4, P6) each preceded by a foam dispensing arch (A3, A5, A7), a polishing portal frame (P8) preceded by a foam dispensing arch (A7), a rinsing arch (A9), a drying portal frame (P10) The control unit (102) controls the operation of the arches and the portal frames by integrating a combination for operating the high pressure portal frame (P2) and the portal frames (P4, P6, P8), only allowing the operation of the polishing portal frames (P4, P6, P8) as polishing portal frames if, previously the high pressure portal frame (P2) has been operated

Structural behaviour of an innovative cold-formed steel building system

Abstract: Cold-formed steel structures have been in service for many years and are used as shelters for both domestic and industrial purposes. To produce an economical product, manufacturers have typically based their designs on the simple portal frame concept. As there is almost a direct relationship between overall cost and the weight of steel in a portal frame structure, it is of great importance to provide a structure with the minimum amount of steel whilst providing structural adequacy. Portal frame sheds have been refined continuously for many years, with only minimal amounts of savings in steel. Therefore, to provide even greater savings in steel, an innovative building system is required. Modern Garages Australia (MGA) is one of the leading cold-formed steel shed manufacturers in Queensland. MGA has recently developed such an innovative building system that has significant economic savings when compared with portal frame structures. The MGA building system has two key differences to that of the conventional portal frame system. These differences are that the MGA system has no conventional frames or framing system, and it has no purlins or girts. This results in the MGA system being completely fabricated from thin cladding, which significantly reduces the quantity of steel. However, the key problem with this building system is that the load paths and structural behaviour are unknown, and therefore the structure cannot be analysed using conventional methods. Therefore, the objectives of this research were to first investigate the structural behaviour of this new building system and its adequacy for an ultimate design wind speed of 41 m/s using full scale testing. The next objectives were to use finite element analysis to optimise the original MGA building system so that it is adequate for an ultimate design wind speed of 41 m/s, and to develop a new improved cold-formed steel building system that has greater structural efficiency than the original MGA building system. This thesis presents the details of the innovative MGA building system, full scale test setup, testing program, finite element analysis of the MGA building system and the results. Details and results from the optimisation of the MGA building system, and the development of a new improved cold-formed steel building system are also presented. The full scale experimental investigation considered the required loadings of cross wind, longitudinal wind and live load test cases and simulated them on the test structure accurately using an innovative load simulation system. The wind loads were calculated for a 41 m/s ultimate design wind speed. Full scale test program included both non-destructive and destructive tests. The finite element analyses contained in this thesis have considered cross wind, longitudinal wind and live load cases, as well as the destructive load case of the MGA building system. A number of different model types were created and their results were compared with the experimental results. In general, two main model types were created. The first type consisted of a 'strip' of the MGA building system (Strip model) and the second modelled the full structure (Full model). Both of these model types were further divided into models which contained no contact surfaces and those which contained contact surfaces to simulate the interfaces between the various components such as the brackets and cladding. The experimental test results showed that the MGA test structure is not suitable for an ultimate design wind speed of 41 m/s. This conclusion is a result of a number of observed failures that occurred during the extensive testing program. These failures included local buckling, crushing failures, and distortional buckling of the cladding panels. Extremely large deflections were also observed. It was calculated that for the MGA building system to be adequate for the design wind speed of 41 m/s, a cladding thickness of 0.8 mm was required. This also agreed well with the finite element analysis results which concluded that a cladding thickness of 0.8 mm was required. In order to avoid the increased use of steel in the building system, a new improved cold-formed steel building system was developed and its details are provided in this thesis. A finite element model of this new improved cold-formed steel building system was created and the results showed that the new building system was able to achieve a load step equivalent to an ultimate design wind speed of 50.4 m/s and was approximately 250% stiffer than the original MGA building system, without any increase in the overall weight of the building system. It is recommended that this new improved cold-formed steel building system be further developed with the aid of finite element modelling and be tested using a similar full scale testing program that was used for the original MGA building system.

Multi-dimensional digital control working machine

Abstract: The utility model relates to a processing machine tool controlled by multidimensional digitization, which is characterized in that the processing machine tool is composed of a machine tool body, lower guiding rails, a Y-direction driving mechanism, a working table, a portal frame, a Z-direction driving mechanism, upper guiding rails, a cutter frame mechanism, an X-direction driving mechanism and an electric control box, wherein the two lower guiding rails are arranged at both sides of the machine tool body; the portal frame is arranged on the two lower guiding rails; the Y-direction driving mechanism arranged in the machine tool body is connected with the portal frame to drive the portal frame to move on the lower guiding rails forwards and backwards along a Y direction; the working table is arranged on the machine tool body; the Z-direction driving mechanism is arranged above the portal frame; the two upper guiding rails are arranged at both sides of a box body of the Z-direction driving mechanism; the cutter frame mechanism is arranged on the two upper guiding rails, and the Z-direction driving mechanism is connected with the cutter frame mechanism to drive the cutter frame mechanism to move on the upper guiding rails upwards and downwards along a Z direction; the X-direction driving mechanism arranged at one side of the portal frame is connected with the Z-direction driving mechanism, and the X-direction driving mechanism can drive the Z-direction driving mechanism to move on the portal frame leftwards and rightwards along an X direction; the electric control box is arranged at one side of the machine tool body, and is respectively connected with the Y-direction driving mechanism, the Z-direction driving mechanism and the X-direction driving mechanism. The utility model has the advantages of convenient operation, low cost and high producing efficiency, and the cost of the utility model is 1/3 of that of a numerical control machine tool for processing metal.

Determination of a road traffic jam situation is made using a mobile unit that allows movement of vehicle through a portal frame

Abstract: The information gathering system is in the form of a mobile unit [1] having a driver unit [4] mounted on top of a portal frame that forms a wheeled vehicle. Other road users may pass through the portal while the driver monitors and provides control information. A number of variations are possible in the vehicle design.

In-plane stability performance of portal frame structures with different ratio of depth to span

Abstract: The ANSYS finite element program is used to perform geometrically nonlinear analysis in order to deal with the in-plane stability of the steel portal frames with different ratio of depth to span in which the section sizes of the beam and the column are different, The stability behavior of portal frame subjected to roof uniform loading is investigated and the instability load is obtained by analyzing the load-deflection curves. It is indicated that when the ratio of depth to span is equal to or larger than 1∶3, the instability mode is sides-away buckling, and the main moment and axial force in the beam have a negligible effect on stability of the portal frame?When the ratio of depth to span is less than 1∶3, the instability mode of the portal frame is associated with the ratio of depth to span?stiffness factor ratio of beam to column,the instability mode of the portal frames is mostly symmetric, and the above-mentioned effect of main moment and axial force on the stability behavior of portal frame can not be negligible.

Chapter 5 – Members Subjected to Bending and Compression

Abstract: This chapter describes members subjected to bending and compression. Hollow sections are most likely to experience combined bending and compression in low rise portal frame structures. In rigid frame action both the beams and columns experience bending. The beams are subjected to almost zero net axial force, and the columns generally experience relatively low axial compression loads. Members subjected to combined bending and compression are sometimes referred to as “beam-columns” representing the two types of design actions they are intended to resist. According to this chapter, the behavior and strength of a member under bending and compression is related to the strength under bending alone and compression alone with three key modifications. Moreover, the bending moments in the frame determined from a first-order analysis are termed the primary moments. The additional moments resulting from the P-Δ effect due to joint sway and the P-δ effect due to member curvature are called the secondary moments. This chapter concludes that it also makes reference to the behavior and strength of hollow sections under pure bending and pure compression.

Edge folding door type rigid-framed structure

Abstract: The present invention is one kind of wing-edged bending portal frame structure used widely in light house and roofing member The present invention features that the portal frame structure consists of two beams and two columns, the beam is equal-section, various-section or sectional various-section member, and the column is equal-section or various-section member The beams and the columns are connected via end plate connecting node, and the end plate connecting node has high strength frictional or bearing screw bolt Both beam and column are wing-edged bent member with I-shaped cross section, and have high bearing capacity and low cost

Resistance of a Portal Frame Bridge Pier Under Earthquake Waves from Arbitrary Directions

Abstract: Steel portal frames are used in Japan as basic structural frames for viaducts in metropolitan areas These structures may be subject to both near-field and far-field earthquake motions from all directions Although for isolated single piers the earthquake-resistant design appears to be well established, the earthquake response and the resistance are not fully clarified for portal frames A study on elastoplastic finite displacement analysis by a finite element model for earthquake resistance of steel portal frame piers of an elevated highway is presented The incidental earthquake waves are assumed to come from arbitrary directions; for simplicity, the analysis considers five different directions covering the in-plane of the frame (0 deg from the transverse direction of the bridge axis) and the out-of-plane directions (30 deg, 60 deg, 75 deg and 90 deg) Some results were compared with those from experiments on portal rigid-frame bridge piers under in-plane loading conducted at Kyoto University It was found that it is important to take the correlation of in-plane and out-of-plane responses into consideration for the rational earthquake-resistant design of a portal frame bridge pier

The integral stability analysis of the long-span tension-chord portal frame

Abstract: Publisher Summary The chapter discusses the integral stability analysis of a long-span tension-chord portal frame. A tension-chord portal frame is composed of some simple space structure units, such as upper beam, bottom chord cable, strut, etc. Each unit can make up for each other's shortcomings, so stresses are more reasonable, and therefore materials can be economized and longer span can be obtained. To design this kind of newly long-span space hybrid structure safely and economically, the stability performance of the structure should be studied. The tension-chord portal frame is an integrality that consists of cross-beam, strut, cable wire, etc. Once a structural member loses the stability and is out of shape, it must affect other structural members that connect to it. According to these analyses, the finite-element method is used to analyze the integral stability of a tension-chord portal frame in the chapter.

Design of large-span portal frame system

Abstract: Publisher Summary The chapter examines a warehouse project in Beijing and discusses the design principle of large-span portal frames with complex system. The main rigid frames of this structure consists of two steel large-span frames whose spans are both 36m, some of the frames even have 72m long span, and a part of the structure has a suspended mezzanine floor. The supporting truss is applied under the 72m span frame to ensure the deflections between the frames of different spans compatible. The integral action between the frames and the supporting truss to resist load is considered in the design. The span of the beams in mezzanine floor approximates 30m and the beam depth is limited strictly. In the design, some columns are applied between the beams of mezzanine floor and the roof rafter to form a space frame, and provide adequate loading capacity and stiffness. The project provides a helpful reference to the design of similar structures.