Showing papers on "Portal frame published in 2020"

Eccentric steel brace retrofit for seismic upgrading of deficient reinforced concrete frames

Abstract: The paper presents a simplified static force-based procedure for seismic retrofit design of RC frames using internal eccentric steel braces (ESBs), connected to long beam at distance of L/8 from beam ends, to enhance seismic resistance of the frame. The technique uses the linear static procedure given in ASCE 7-16 for calculation of appropriate design base shear for frame analysis, and the AISC 360-16 seismic provisions for preliminary design of steel braces. Response modification factor R was derived based on simplified kinematics of rigid frame response and flexure hinging of link beam, to reduce the elastic base shear force for lateral load analysis of frame and design of steel braces. This shifts plastic hinges from columns, and reduces joint shear deformation, by means of capacity protected braces and beam shear. The procedure was used for the preliminary design of ESB retrofitting technique for a two-story RC frame, employing hollow box steel sections. Quasi-static cyclic tests were performed on both as-built and ESB retrofitted portal frame panels under multiple-levels of lateral displacements demands. The tests performed on frames were analysed to understand the damage mechanism and retrieve the essential seismic response properties: force–displacement capacity curves, hysteretic cyclic response and hysteretic damping, and to establish performance-based story drift limits. The experimental data was used to calibrate finite element based nonlinear numerical models in SeismoStruct. Nonlinear static pushover analysis of considered two-story ESB retrofitted frame was carried to quantify structure ductility and response modification factors. The preliminary design was verified through nonlinear time history analysis (NLTHA) for both design base earthquakes and maximum considered earthquakes. Proposed seismic design of ESB retrofit for multi-stories RC frames having three to six stories has been presented and verified through NLTHA. It indicates the promising behaviour of ESB retrofit technique as well as the efficiency of the proposed simplified design procedure.

On the Positioning of a Piezoelectric Material in the Energy Harvesting From a Nonideally Excited Portal Frame

Abstract: In this paper, we consider the application of the piezoelectric energy harvesting using a portal frame structure of two-degrees-of-freedom. The piezoelectric material is considered as a linear device using a capacitive mathematical model. The portal structure is of two-degrees-of-freedom considering with quadratic coupling between the first and second modes of vibration. 2:1 internal resonance between the first and second modes is set, which is a particular condition of this type of system due to the appearance of a saturation phenomenon. As this phenomenon causes the system to start vibrating from the second mode and, at steady-state, vibrates at the first mode, the objective of this work is to verify the energy uptake, considering the different positioning of a piezoelectric material, which is coupled to the supported beam and/or to the column. In addition, the structure is excited by a nonideal DC motor with a limited power supply. The results show a considerably nonlinear behavior due to the nonideal motor, and, with the saturation phenomenon, it is more efficient to collect energy by coupling the PZT to the column. The investigation of the stability of the system due to the piezoelectric coefficient Θ is also taken into account, which is carried out by numerical tools as phase planes, Poincare maps, bifurcation diagrams, and 0–1 test.

Spatial Temperature Differences in Portal Frame Bridges

Abstract: Thermal actions are considered in the design of bridges, as temperature variations can lead to restraint stresses and subsequent cracking. However, load descriptions are in some cases oversimplified or incompatible with modern applications, and background studies are limited. This paper therefore aims to develop a more detailed load description for the load case describing temperature differences between structural parts in bridges, focusing on portal frame bridges. The temperature in portal frame bridges is investigated by performing long-term thermal simulations using weather data from several locations in Sweden, and thereafter performing statistical analyses of the resulting temperature variations over time. The study gives suggestions of both characteristic and quasi-permanent values to be used in design based on the statistical analyses, and also notes a gradual change in temperature between structural parts, which could be considered in the design. The resulting quasi-permanent values are significantly lower than the values given in the Eurocode for temperature differences between structural parts, which, in turn, will lead to smaller and more realistic stress values in bridge design. (Less)

Remarks on energy harvesting of nonlinear charge and voltage piezoelectric models in a two-degrees-of-freedom nonlinear portal frame model:

Abstract: In this paper, a piezoelectric energy harvesting application on a portal frame of two-degrees-of-freedom considering a quadratic coupling between the coordinates with two-to-one internal resonance ...

Global structural analysis of high-rise hospital building using earthquake resistant design approach

Abstract: Building designed has 1 to 8 floors with the quality of concrete f'c of 33.2 MPa, steel quality (fy) 400 MPa, and shear stress of 240 MPa. The building is analyzed by 3D structure modeling through ETABS Version 9.7 program by following all the rules and regulations applicable in Indonesia, such as the guidance of building structure and non-building, SNI 1726: 2012. This building design system is a high-rise building structure planned with a portal frame system with beams and columns as the main elements of structures made of conventional concrete. The beam carries the load transversely of its length and transfers the load to the vertical columns that accumulate it. The column accepts the load axially by the beam and transfers the load to the foundation. This building structure uses a special moment frame structure system (SRPMK) structure, considering that the hospital building is safe against earthquakes and complains about the strong column weak beam concept.

Impact force identification in structures using time-domain spectral finite elements

Abstract: During the launch and subsequent life of a spacecraft, there are various transient loads due to stage separation and micro-meteorite impact which a spacecraft structure must be designed to withstand. However, the force histories for these transients at these locations are not available to design the structure due to practical considerations like mounting of instrumentation. To address this problem, a new algorithm for performing impact force identification based on time-domain responses measured at various locations is proposed. The time-domain spectral finite element model is adopted as it requires a fewer number of measured responses which clearly has an advantage with respect to conventional finite element method. Hence, we use time-domain spectral finite element method, to generate the mass, stiffness, and damping matrices, which are required to perform force identification. Experiments are performed to obtain the time-domain responses on the beam and portal frame structures on which force identification is performed. The efficiency of the new algorithm is demonstrated using a variety of responses and different one-dimensional structures. However, the proposed algorithm is general in nature and can be used for one-, two-, and three-dimensional structures and with conventional generalized finite element model. The results from the proposed algorithm show an excellent match between the reconstructed force histories and the experimentally measured force.

Compaction device of large circular sawing machine

Abstract: The invention relates to the field of circular sawing machines, in particular to a compaction device of a large circular sawing machine. The compaction device comprises a steel part portal frame. Three pressing oil cylinders are horizontally mounted and fixed to the top end of the steel part portal frame, the output end of each steel part portal frame is connected to an oil pressure telescopic rod, the bottom end of the oil pressure telescopic rod is connected and fixed to a pressing plate, the bottom end of the pressing plate is arranged on the material plate, and guide bars are vertically mounted and fixed to two sides of the top end surface of each pressing plate, the guide bars are slidably inserted into guide sleeves, and the guide sleeves are mounted and fixed to the steel part portal frame. By clamping the material plates in the sawing machine by way of compacting the material plate by means of an oil pressure of the portal frame, the pressures of the oil cylinders are acted tothe material plates by means of actions of pressure heads. By means of characteristics of large pressures of the oil cylinders and stable and adjustable oil cylinders, the material plates can be clamped firmly. It is ensured that the material plates are stable and do not vibrate during sawing. The three oil cylinders are arranged in a ''-'' shape, so that the pressures acted to the material platesare uniformly distributed. The large circular sawing machine has a good effect of sawing large-sized material plates of different sizes particularly.

Dynamics Characterization of a U-Shaped Micro-Resonator Portal Frame

Abstract: We present a study of the natural (resonance) frequencies of a tunable in-plane Microelectromechanical portal frame (U-shape) under DC electrostatic loads. The structure is designed and fabricated to excite the in-plane anti-symmetric (sway, first) and the symmetric (second) modes. Experimental results show high tunability of the resonance frequencies of both modes due to the electrostatic forces. Finite element simulations show good agreement with the experimental measurements. Further simulations are presented for the tunability of the natural frequencies of other higher-order modes using various electrode configurations. Frequency-response curves are presented for pure AC actuation of the first two modes showing strong nonlinear softening behavior due to the geometric nonlinearities of the portal frame. [2020-0269]

Heuristic Catenary-based Rule of Thumbs to Find Bending Moment Diagrams

Abstract: There are numerous nature-inspired curves representing certain structural behaviour being utilised in form-finding process by some famous architects. By closely scrutinising these forms, some interrelated morphological analogies between different structural forms and functions, such as the similarity between free-standing tension-only elements and the shape of bending moment diagram of a beam under the same load condition, can be explored. Most studies in the field of statics principles have only focused on developing numerical and mathematical approaches which are not suitable for practitioners who prefer quick access to the general forms. This paper first gives a brief overview of the most common archi-structural forms through the history of the architecture, and attempts to find the shape of bending moment diagrams through a new simple heuristic method based on drawing an analogy between natural tension-only forms and the diagrams. The purpose of this research is to propose a shortcut to diagram drawing substituting the general time-consuming methods as well as enhance the architects' perception of bending behaviour of a structural element. A holistic approach is utilised, integrating the natural curves, bending moment diagrams and some rule of thumbs used to define the tapered beam or portal frame general shapes. This simple non-computational method can ease the design process. It will also be useful for educational purposes as well as pre-design phase conception including identification of the critical points of bending elements as well as designing tapered beams and portal frames.

Detection of Anomaly in a Pretensioned Bolted Beam-to-Column Connection Node Using Digital Image Correlation and Neural Networks

Abstract: Bolted connections, commonly applied in civil engineering structures, have many advantages. According to current trends, bolted connections in steel structures are designed as prestressed ones. Unfortunately, precise control of the prestressing forces is difficult, while the loosening (due to, e.g., dynamic interactions) may be dangerous for the entire structure. There are many control methods applied in the determination of the tightening level, among which are vision-based methods. The methods described so far enable—thanks to image processing—damage detection in connections with visible connectors. The level of the considered loosening was significant—in many cases, changes in connectors were visible with the naked eye, whereas the procedure presented here enables the detection of very small changes, impossible to detect without manual inspection of every single connector. It is not necessary to observe the connectors directly, but the near surrounding of the node should be visible. As a measurement technique, Digital Image Correlation (DIC) was used. The applied measurement method and the high sensitivity of the presented procedure makes the presented research original. The currently presented procedure, employing Artificial Neural Networks, based on the laboratory examination of an example of one selected beam-to-column connection of a two-story steel portal frame, was perfect in the detection of a change and in the determination of the number of loosened rows, 95%, and their location, 94%, with the number of false alarms below 1%.

Height limit alarm device for highway engineering

Abstract: The utility model discloses a height limit alarm device for highway engineering. The height-limiting alarm frame comprises a height-limiting alarm frame body, a fixed cross beam is mounted at the topend of the height limiting alarm frame main body; warning boards are installed in the middles of the two ends of the fixed cross beam, vertical rods are installed on the two sides of the lower portionof the fixed cross beam, fixed sliding grooves are formed in the vertical rods, telescopic belts are installed on the upper portions of the interiors of the fixed sliding grooves, and height limitingrods are installed in the fixed sliding grooves. According to the utility model, the vertical rods, the stone pier frame, the bottom plate and the steel reinforcement cage form an integral portal frame; a conventional iron portal frame is easy to bend due to collision; the height-limiting alarm frame is simple in structure and poor in anti-collision capacity, the vertical rods, the stone pier frame, the bottom plate and the steel reinforcement cage are combined into a whole, the firmness of the portal can be improved, the anti-collision capacity can be improved through the stone pier frame, the service life of the height-limiting alarm frame body is prolonged, and the height-limiting alarm frame body and the ground can be installed more firmly through the bottom plate and the steel reinforcement cage.

Composite board cutting device

Abstract: The utility model belongs to the field of wood cutting equipment, and particularly discloses a composite board cutting device which comprises a cabinet body, a portal frame assembly and a cutting assembly. Wherein the cabinet body is a cuboid-shaped box body, the upper surface of the cabinet body is provided with a workbench, the portal frame assembly is arranged above the workbench, the cutting assembly is fixed on the portal frame assembly, and the cutting assembly can move along with the portal frame assembly in three X, Y and Z directions which are perpendicular to one another. According to the composite board cutting device, chippings can be collected in the cutting process, and the chippings are prevented from flying; the cutting precision is high, and cuts are straight and flat; theoperation is simple and the working efficiency is high.

Bending test device for precast pile

Abstract: The utility model discloses a bending test device for a precast pile. The bending test device comprises a supporting assembly, a first sliding assembly, a second sliding assembly, a measuring assemblyand a third sliding assembly, the supporting assembly comprises a bottom plate and a portal frame, and the portal frame is welded to the upper surface of the bottom plate. The third sliding assemblyis arranged on the inner side, close to the portal frame, of the upper surface of the bottom plate; when a user needs to carry out a bending test on the precast pile; firstly, a precast pile is placedon a third sliding assembly; the third sliding assembly works; the precast pile is moved to the position below the measuring assembly, and then the second sliding assembly is moved to the position over the third sliding assembly through work of the first sliding assembly, so that it is convenient for the measuring assembly to apply pressure to the top of the precast pile, the precast pile is conveniently guided out through work of the third sliding assembly after measurement is completed, and therefore the next precast pile is conveniently measured.

Translational in-place hoisting device and method for equipment in sealed plant

Abstract: The invention discloses a translational in-place hoisting device and method for equipment in a sealed plant. The translational in-place hoisting device comprises a support, a plurality of pin rollers,a first hoisting portal frame and a second portal frame, and the work face of the support is a rectangular frame formed by two cross beams and two longitudinal beams. Multiple grooves are machined ineach of the two cross beams, and the upper ends of the grooves are open. The pin rollers are mounted on the grooves of the two cross beams in a rolling manner. The pin rollers are arranged in parallel, and the diameter of the pin rollers is smaller than or equal to the width of openings in the upper ends of the grooves. The first portal frame and the second portal frame are both mounted on the support, and at least one set of first lifting traction equipment is mounted on each hoisting portal frame. At least one set of second lifting traction equipment is mounted at the end of the support. According to the device, equipment replacing work in the sealed plant can be achieved, and the device is especially suitable for in-place mounting work of the equipment below horizontal elevation.

Concrete block cutting device with sweeping function

Abstract: The utility model relates to a concrete block cutting device with a sweeping function, which comprises a portal frame arranged on a conveying track in a spanning manner, a vertical cutting device is arranged on the portal frame, a sweeping device is arranged at the downstream end of the portal frame, the sweeping device comprises a fixed bracket fixedly connected with the portal frame, and the fixed bracket extends to the downstream side of the portal frame; an adjusting support is fixed to the downstream end of the fixing support, a brush assembly is arranged at the lower end of the adjustingsupport, and an anti-stacking gap is reserved between the brush assembly and the vertical cutting device. The cleaning device can clean materials generated by cutting of the vertical cutting device,cleanliness of the periphery of the equipment is guaranteed, and meanwhile the surface quality of concrete leather can be improved. The sweeping device is reasonable in structure, the anti-stacking gap is reserved between the brush assembly of the sweeping device and the vertical cutting device, and the situation that due to the fact that the brush assembly is too close to a cutting steel wire, materials on the upper side face of a concrete blank are stacked to damage the cutting steel wire rope can be avoided.

Working method for diameter expanding device for steel tube processing

Abstract: The invention relates to the technical field for steel tube processing, in particular to a working method for a diameter expanding device for steel tube processing. The diameter expanding device comprises a working platform, wherein the left side of the top of the working platform is in bolt connection with a portal frame; the top of the portal frame is in bolt connection with a lifting mechanism;the bottom of the lifting mechanism is in bolt connection with a placing mechanism; the lifting mechanism supports the placing mechanism; the right side of the working platform is in bolt connectionwith a moving mechanism; the right side of the top of the working platform is in sliding connection with a slide frame; the slide frame is L-shaped; the right side of the slide frame is rotatably connected with a rotary rod; and the right end of the rotary rod penetrates through the right side of the slide frame, and is in sleeve connection with a transmission wheel. The working method has the advantages of being capable of reducing friction between a diameter expanding head and the steel tube, and conveniently loading and unloading, solves the problem that an existing device diameter expanding head generates fierce friction with the inner part of a pipeline to increase burden of a power device, and also solves the problem that loading and unloading operation cannot be performed by only one steel tube in a device operation process.

Automatic guide forklift

Abstract: The embodiment of the utility model discloses an automatic guide forklift, relates to the field of logistics storage, and can effectively reduce the thickness of the front end of a pallet fork. The automatic guiding forklift comprises a vertically-arranged portal frame, and a walking device is arranged below the portal frame. Wherein a pallet fork is arranged on one side of the portal frame; the other side of the portal frame and/or the width direction of the portal frame are/is provided with functional assemblies arranged in the height direction of the portal frame. The functional assembly comprises a pallet fork driving device, a battery and a main control unit, the pallet fork driving device and the battery are connected with the main control unit, and the pallet fork driving device isfurther connected with the pallet fork. The utility model is suitable for the transportation of goods.

Method for positioning by using laser three-dimensional projection in hull construction

Abstract: The invention provides a method for positioning by using laser three-dimensional projection in hull construction A projector fixing portal frame is arranged on the ground A ship body segmented structure is arranged below the portal frame, a laser projector is fixed to the upper portion of the fixed portal frame, the outline of a T-shaped profile projected by the projector of the laser projectorirradiates the faces of the segmented structures on the two sides, the segmented structures are arranged on a segmented structure jig frame, and a projector software system is fixed to the bottom faceof one side of the fixed portal frame through a support T-shaped material structure positioning point and line projection is carried out through the steps of ship body structure model processing, projection coordinate system conversion, establishment of a ship body T-shaped material structure projection positioning file, format importing into a laser projector software system, establishment of aprojected ship body structure real coordinate system, establishment of an operation package and projection operation The positioning precision of the hull structure can be detected through laser projection images The method is suitable for being applied to laser three-dimensional projection positioning in hull construction

Internal medicine nursing object hanging portal frame

Abstract: The utility model provides a portal frame for hanging medical nursing articles. The portal frame comprises base columns, lifting columns and a cross beam, the lifting column is sleeved with a verticalfoundation column from top to bottom, and the lower end of the foundation column is fixed to a horizontal bottom plate. The bottom positions, close to the two ends, of the cross beam are arranged atthe top ends of the lifting columns in a sleeving mode; a plurality of height limiting holes are formed in the lower part of the foundation pillar and are distributed in two symmetrical straight lines; a sliding groove is formed in the upper surface of the cross beam. The base columns, the lifting columns, the cross beams and the like are arranged; the installation angle and the installation height are convenient to set; the support does not need to be installed on the wall surface in advance, the disassembly position does not need to be considered, and the equipment support, the infusion bottle hook and other appliances can be installed in the sliding groove of the cross beam through other modules matched with the structures, so that the purpose that medical equipment or equipment occupies less activity space of people beside a bed of a critical patient in the internal medicine department is achieved.

Paving device of asphalt mixture pavement paver

Abstract: The utility model discloses a paving device of an asphalt mixture pavement paver. The utility model belongs to the technical field of pavers. The device comprises a bearing frame, a portal frame, an asphalt tank, a cleaning agent box, a stirring assembly, a paving assembly and a cleaning assembly, the portal frame is arranged at the rear end of the bearing frame; the asphalt tank and the cleaningagent box are both arranged on the bearing frame. The stirring assembly is arranged in the asphalt tank; the paving assembly is mounted on the portal frame; the cleaning assembly is installed on the portal frame and communicates with the cleaning agent box, the paving assembly comprises a lifting plate, a paving roller and a lifting part, the paving roller is installed at the bottom of the liftingplate, the lifting part is arranged at the top of the portal frame, and the bottom end of the lifting part is fixedly connected with the lifting plate. According to the utility model, the problems that the paving roller cannot adjust the required paving thickness and is very inconvenient, and asphalt adhered to the paving roller is not easy to clean after paving, so that the service life of the paving roller is influenced are solved.

Full-automatic metal additive submerged arc printing equipment and method

Abstract: The invention disclose full-automatic metal additive submerged arc printing equipment. The equipment is provided with a base, and a workbench, a first portal frame and a second portal frame are arranged on the base; an auxiliary agent laying mechanism, a slag removing mechanism and a slag knocking mechanism are arranged on the first portal frame; a printing mechanism and an auxiliary agent removing mechanism are arranged on the second portal frame; the first portal frame drives the auxiliary agent laying mechanism to perform auxiliary agent laying operation at the designated position of the workbench; the second portal frame drives the printing mechanism to perform workpiece printing operation on a printing substrate of the workbench; the second portal frame drives the auxiliary agent removing mechanism to perform auxiliary agent removing operation on the surface of the printed workpiece; the first portal frame drives the slag knocking mechanism to knock solid waste slag adhering to the surface of the printed workpiece to be loosened; and the first portal frame drives the slag removing mechanism to remove the loosened waste slag. According to the equipment and method, the full-automatic production is achieved, and the production efficiency is improved.

Portal frame device for assisting in dismounting construction tower crane counterweight

Abstract: The utility model discloses a portal frame device for assisting in dismounting a balance weight of a construction tower crane. The device comprises a portal frame erected on a building roof, the portal frame comprises two stand columns and a frame top hoisting system supported at the top ends of the two stand columns. The frame top hoisting system comprises a bearing beam with the two ends connected with the top ends of the two stand columns correspondingly, a sliding trolley movably connected with the bearing beam, and a chain block connected with the sliding trolley. A chain block is used for hoisting an upper chord of the cargo boom; the middle part and the top part of each upright post; wherein two steel wire ropes are respectively pulled from two mutually perpendicular directions, thesteel wire ropes are fixed on a roof through anchor bolts and are tensioned by a rope tensioner, the hydraulic vehicle is used for bearing the detached counterweight and transferring and stacking thecounterweight, and a lifting mechanism for placing the detached counterweight on the hydraulic vehicle is arranged on the counterweight detaching bracket. According to field conditions, the portal frame is adopted to assist in dismounting the tower crane counterweight, and the operation is convenient, safe and reliable.

Numerical control planogrinder capable of easily cleaning machining waste

Abstract: The utility model discloses a numerical control planogrinder capable of easily cleaning machining waste. Including a machine frame, a portal frame is arranged at the upper end of the rack. A workbenchis arranged at the lower end of the portal frame; a sliding seat and a screw rod are arranged on the portal frame; the sliding seat is in sliding connection with the portal frame through a sliding rail; the screw rod is rotationally connected with the portal frame through a bearing seat; a first motor is arranged at one end of the lead screw, the first motor is in transmission connection with thelead screw through a gear box, the lead screw is in transmission connection with a sliding base through a lead screw nut, a fixing base is arranged at the front end of the sliding base, a second motor is arranged on the back of the sliding base, and the sliding base is in sliding connection with the fixing base through a sliding groove. Compared with a traditional numerical control planogrinder,the numerical control planogrinder has the advantages that waste in the cutting fluid can be filtered through the filter plate in the first supporting table and the precipitation tank in the second supporting table, and the numerical control planogrinder is easy to use and convenient to clean.

Rigidity testing device

Abstract: The utility model provides a rigidity testing device. The device comprises a test table top, a portal frame, a first test mechanism, a second test mechanism, a third test mechanism, a support and a displacement sensor. The portal frame is fixed on the test table board; the first testing mechanism is mounted at the top of the portal frame and is vertically arranged downwards; the second testing mechanism and the third testing mechanism are symmetrically mounted on left and right supporting columns of the portal frame and are oppositely arranged; two displacement sensors which are diagonally arranged are fixed on the test table board through a bracket; the first testing mechanism, the second testing mechanism and the third testing mechanism are the same in structure and each comprise a testing air cylinder, the testing air cylinders are fixed to the portal frame, the testing heads are fixed to telescopic rods of the testing air cylinders, the pressure sensors are fixed to the front endsof the testing heads, and the pressure blocks are fixed to the front ends of the pressure sensors. The rigidity testing device is high in automation degree, capable of automatically measuring the rigidity of the tested object in the axial direction and the vertical direction, and high in measuring precision.