Showing papers on "Portal frame published in 2006"

Experiments of Cold-Formed Steel Connections and Portal Frames

Abstract: A series of connection tests which were composed of closed cold-formed steel sections were conducted to investigate the performance of the connections constituting a pitched roof portal frame. The flexural strength of the section was investigated first and the structural behavior of the connections including the moment-rotation relation, the yield, and ultimate moment capacity of the connections were studied experimentally. The connection test specimens consisted of column base, eave, and apex connections of the portal frame. The main factors of the connection test were the thickness and the shape of the mild steel connection element. Finally, the portal frame was tested under both constant vertical and increasing horizontal loads to failure. The experimental results were compared with the numerical analysis results. The semirigid connection concept was considered for the analysis of the portal frame using the secant stiffness of the connections, which were estimated from the moment-rotation curves of the connections tested.

Development of wooden portal frame structures with improved columns

Abstract: In Japan, the lifetime cycle of most housing lasts around 20–30 years. A governing factor in this respect is poor durability due to old-fashioned use of the house. As a solution of this problem, houses can be built with a skeleton structure that allows free partition of spaces by future owners. To develop the skeleton structure effectively, multistory frames with spans of 6 to 10 m are required. For this reason, attention has been focused on the behavior of multistory timber frame structures. In this article, two types of wooden portal frame structures are proposed. Both structures have improved vertical columns with short horizontal members glued in. The aim of this study was to investigate structurally effective solutions with these types of columns. The first type of the new structure changed the location of the moment-transmitting ductile connection with the improved columns. The second type of structure used an extended panel zone. Nine portal frame specimens were tested. The stiffness values were improved by around 1.7 and 3.5 times when compared with the control, and the strength was improved by around 1.25 and 1.45 times.

Automatic assembling machine for digital-controlled II-type steel

Abstract: The utility model relates to an automatic assembling machine for digital-controlled H-type steels. The front part is a portal tower structure, and the upper part of a machine frame is provided with a downward pressing oil cylinder; the downward pressing oil cylinder is connected with a movable cross beam, and the movable cross beam is provided with an automatic tracking frame with welded elevation angles; a positioning box for underbelly wing plates and the clamping box are arranged at a portal base, and an input rolling channel is arranged under the portal frame; machine frames at both ends of the rolling channel are provided with automatic centering and clamping shafts for web plates, and a conveying motor is connected with a driving roller; a conveying chain wheel on the driving roller is connected with a roller on the input rolling channel by a chain, and welding seams have automatic tracking; two pneumatic tracking welding guns used for welding upper flanges are fixed on the cross beam and can carry out variation along with the variation of the height of H-type steel web plates, therefore H-type steels with variable cross sections can be welded; two pneumatic tracking welding guns used for welding lower flanges are fixed on an upright post, the welding guns are firmly fixed and the quality of welding seams is stable and reliable.

Experimental cyclic tests and retrofit of RC hollow piers

Abstract: The main purpose of this paper is to present an experimental campaign of reinforced concrete hollow section piers with different cross sections under cyclic loading, comparing the obtained results with those obtained for the same piers after seismic retrofitting, and evaluating benefits concerning their structural behaviour. The setup of the RC pier experimental tests was designed to carry out cyclic horizontal top displacements with axial load using two orthogonal actuators with a sliding device to allow pier top displacements and rotations, in spite of the vertical actuator being fixed to a steel portal frame. Representative of typical bridge construction, square and rectangular hollow section RC piers were tested at LESE – the Laboratory of Earthquake and Structural Engineering at Faculty of Engineering of University of Porto. The structural behaviour and safety improvement of these piers are presented, with the retrofit techniques adopted, as well as the illustration of the external and internal damage pattern. The framework of this study is, therefore, to develop and calibrate procedures enabling the evaluation of the different retrofit solution efficiency, their possibilities and fields of application.

Simple plate bending machine

Abstract: The utility model discloses a simple plate bending machine, which is provided for overcoming the defects of low accuracy of process of bending plate, high cost, energy wasting, low efficiency and narrow range of application of processing plates existing in the prior art. A bottom plate in a portal frame is provided with a concave die which is matched with a bending angle of the plate. The upper part of the concave die is provided with a convex die which moves along an upright post of the portal frame upward and downward and corresponds to the concave die; both ends of the convex die are supported by springs; The upper part of the convex die is provided with a hydraulic lifting and lowering device which is propped on a cross beam of the portal frame. Because the bending machine has simple structure and low cost, the bending machine can be made in middle and small mechanical processing factories. The plates are bent by the die so as to guarantee unified dimension and quantity. The utility model adopts the hydraulic device to add pressure and has the advantages of high processing efficiency, low labor intensity, no wasted energy resource, low processing cost and high safety. The bending machine can be suitable for processing the plates which are made of various materials. One bending machine can process the plates with a plurality of sizes so long as replacing the dies. The utility model is flexible and changeable and is particularly suitable for being used for the middle and small mechanical processing factories.

Development of a portal frame system on the basis of component testing

Abstract: This paper describes tests carried out on components of a cold-formed steel portal frame system. The main aim of the tests was to validate the design which was initially based on finite element software.

Structural Fire Performance of Steel Portal Frame Buildings

Abstract: This paper describes a study into the fire behaviour of steel portal frame buildings at elevated temperatures using the finite element programme SAFIR. The finite element analysis carried out in this report was three dimensional and covered different support conditions at the column bases, the presence of axial restraints provided by the end walls, several different locations and severities of fires within the building, different levels of out-of-plane restraint to the columns and the effect of concrete encasement to the columns. From a large number of analyses, it has been shown that the bases of the steel portal frames at the foundations must be designed and constructed with some level of base fixity to ensure that the structure will deform in an acceptable way during fire, with no outwards collapse of the walls. The analyses also showed that it is not necessary for steel portal frame columns to be fire-protected unless the designer wishes to ensure that the columns and the wall panels remain standing, during and after the fire.

Structural-section assembled welding integrating equipment

Abstract: The utility model relates to a section assembled welding integrating machine, which relates to the welding technique. The utility model is concretely characterized in that full automatic welding is carried out on a vertical stripe panel and a web plate, and the section assembled welding integrating machine is formed by integrating the functions of an assembling function before welding and a panel straightening function after welding into a whole body. According to the design provided by the utility model, a machine base is provided with a portal frame, a guide auxiliary roller track for panels, a positioned clamping device for panels, and an assembling driving roller track, wherein both sides of the portal frame are provided with positioned clamping devices for the web plates, and the upper part of the portal frame is provided with an upward pressure multiple-wheel clamping device for the web plates; both sides of an output end of the portal frame are provided with welding gun frames. The utility model can enhance the degree of automation, improve the quality of welding, save labor and fields, and improve the production efficiency.

Application of synthetic fiber ropes to reduce blast response of a portal frame

Abstract: A steel portal frame subjected to an external blast is analyzed. The use of diagonal synthetic fiber ropes to brace the frame is studied. The force-elongation relationship of the ropes when in tension is modeled either as a bilinear function with initial slackness, or a power law based on tests. The effect of the ropes in reducing deflections and plastic strains is determined using the finite element software ABAQUS/Explicit. Inclusion of the influence of strain-rate on the material behavior of the frame is important. Several blast magnitudes and rope stiffness coefficients are considered. Snap loads occur in the ropes if the blast is sufficiently large. Deformations and strains may be reduced significantly by the ropes, and failure may be prevented.

Structural and acoustic response of buildings in the higher frequency range due to surface rail traffic

Abstract: This paper deals with the numerical computation of the structural and acoustic response of a building to an incoming wave field generated by high-speed railway traffic at grade. The source model consist of the model of a moving vehicle on a longitudinally invariant domain coupled to a boundary element model of the underlying ground. The receiver model is based on a substructuring formulation and consists of a boundary element model of the soil and a finite element model of the structure. The acoustic response of the building’s rooms is computed by means of a standard boundary element formulation. The paper investigates the structural and acoustic response of a multi-story portal frame office building.

Electric fork car

Abstract: The utility model discloses an electric fork truck for short distance transportation of goods, which comprises a truck body, a driving wheel and a driven wheel. The front side of the truck body is provided with a portal frame which is a vertically set up rectangle frame and the lower part of the portal frame is hinged with the bottom of the truck body. The portal frame is provided with a slide frame which can slide up and down along the two vertical rims, and the slide frame is provided with a goods fork; the middle part of the portal frame is provided with a hydraulic oil cylinder of which the upper end is fixed at the middle upper part of the portal frame and the lower end is fixed on the slide frame; the top part of the portal frame and the corresponding part on the slide frame are provided with two chain wheels which are wound with chains. The driving wheel is arranged in the middle of the rear side at the bottom of the truck body, and the driven wheel is arranged on the bottom border of the portal frame by means of a wheel shaft and a bearing. When the electric fork truck is used for goods transportation, the truck body has small load and is not easy to damage.

Construction lifting device for floor type steel structural round warehouse

Abstract: The utility model relates to a lifting device for constructing a large sized floor type steel structural round warehouse on site for industry, such as the manufacture of building materials, cement, etc The utility model is provided with a portal frame which is composed of a bottom seat, two side upright posts and a top beam, wherein the top beam of the portal frame is hung with a reverse chain; a circular arc steel plate supporting frame is hung under the reverse chain; the circular arc steel plate supporting frame comprises a steel plate supporting frame seat of which bottom part is provided with a clamping plate; the supporting frame seat is welded a lifting lug; the utility model has the advantages of simple structure, reliable performance and convenient operation; by using the utility model, operators all operate on the ground level, and the utility model prevents aloft work, eliminates potential safety hazard, shortens construction period, and simultaneously, effectively solves the problems of large tonnage, high hoisting, large construction difficulty, etc in the prior warehouse construction The utility model creates ideal construction plant conditions for the construction of the large sized steel structural round warehouse

Concrete hollow block forming machine

Abstract: The utility model relates to a concrete hollow building block forming machine. A portal frame (3) and a machine frame (10) are connected together. A squeezing spiral seat (4) is arranged on a cross beam of the portal frame (3). A squeezing screw rod (5) is assembled on the spiral seat (4). The upper end of the squeezing screw rod (5) is assembled with a static pressure wheel (1) on which a handle of the static pressure wheel (2) is assembled. The lower end of the squeezing screw rod (5) is connected with a pressing block of a combining tire mold (15). The combining tire mold and a clamp apparatus (6) are arranged on the machine frame (10). The lower part of the combining tire mold and the clamp apparatus (6) is provided with a blind heart core mold (9). The lower part of the blind heart core mold (9) is provided with a connecting rod (11) hinged with a draw rod (13). The middle part of the draw rod (13) is hinged on a fixed shaft (14) fixed with the machine frame (10). A concrete building block formed by the utility model has the advantages of energy saving, thermal insulation and high efficiency of construction. The concrete building blocks formed by the utility model can be widely used for a load bearing wall or a non-load bearing wall of a building.

Modelling, analysis and testing of masonry structures

Abstract: In this thesis, masonry churches under horizontal actions are studied. Such structures feature strong seismic vulnerability, both because of the mechanical properties of the material and the particular configuration. Besides, uncertainty of the conventional seismic action is detected. Different codes provide different spectra and, subsequently, different total seismic actions. In order to assess such difficulties, the four basilicas of SGMR, SI, SGMG and SP have been selected. These study cases are analysed with a two step procedure in which the whole structure is analyzed in the linear field through a complete 3D model, and then the single structural elements are assessed in non linear field through FEA and limit analyses. The following remarks can be stated: Certain uniformity in the global plan-altimetric apparatus can be recognised so that the four churches can be regarded as deriving from a sort of three-dimensional global model that changes only for a scale factor. Similarly, a common structural behaviour is expected and in the analyses confirmed. The modal shapes for the analyzed buildings show low torsional and transversal stiffness and great out of the plane deformation. When rigid diaphragms are inserted to model retrofit interventions, greater global stiffness (especially in terms of torsion) and a more monolithic behaviour is detected. It is noticed, furthermore, a stress concentration in the stiffer elements of the buildings (facade elements and in the transept zone) which absorb a larger amount of the total shear. Given the already stated uncertainty in the characterisation of seismic actions, assessment of the behaviour at collapse through spectrum-independent analyses is preferable. In this aim, advanced nonlinear analyses using the code ABAQUS are carried out on the single macro-elements constituting the structural complex. This approach is apparently the most accurate methodology for structural analyses. The results, in fact, are reliable only providing that very precise material characterisation is made. This can be very tricky for historical existing structures. Additional difficulties also derive from the complex geometrical configuration of the studied non-conventional structures. Load-displacement curves providing the collapse multiplier, the horizontal stiffness and the maximum displacement of some control points are obtained for all the macro-elements. These curves are compared with the elastic demands derived through global analyses. It has been shown that generally the bearing capacity of these elements is smaller than the strength demand. Therefore, these constructions are prone to damage and retrofit techniques are necessary. The presence of a rigid slab at the height of the roof has not improved at all the seismic behaviour of the study cases. On the contrary, the effective use of such retrofit technique has to be carefully evaluated specially when adopted in ancient constructions. In the light of the analyses conducted on these complex constructions it is derived that is quite hard following a unique procedure able to define with consistency the most influencing quantities. Therefore, the necessity of defining a handy and suitable methodology for designers is strongly felt. In order to seek a simplified procedure on churches macroelements, a basic structural element in historical buildings, such as the portal frame, has been studied in detail. An analytical exact expression, derived using the kinematic theorem, and an approximate formula have been used for performing a parametric analysis varying geometrical proportions. The extension of the single portal frame to the multi-bay frame has been applied in order to perform the comparison between non linear analyses and simplified analyses. The use of approximate expressions derived for the portal frame implies an averaging of the pier widths. When the medium value is taken into account, generally, greater error percentages are encountered in the model with the load condition considering the only self weight: in this case, the non linear analyses give higher values; on the contrary the limit analysis gives small values of the collapse multiplier. In the load condition of self weight plus dead load, the scatters are smaller. When the maximum pier is taken into account, the values of non linear analysis will be the same but limit analysis values will assume greater values, moving on the right side so that are inside the domain. This evidence has been confirmed for the churches of SGMR, SI and SP. On the contrary, in the church of SGMG, medium values have shown a better comparison with non linear procedure. In the last part of the thesis, the structural behaviour of another typical element in ancient structures is sought: it is the masonry arch. In order to determine the thrust ranges and the minimum thickness, a parametric analysis has been carried out on whole and half arches. A theory for the displacement of the supports has been developed: pointed arches can bear greater displacement than circular arches. This result is confirmed moving one of the supports in any direction into the plane and tracing the domains of possible positions. All the theoretical values have been checked with two different codes and the results agree well. Later, in order to verify these values, an extensive experimental campaign has been held on rigid concrete blocks in small scale representing eight different pointed arches varying eccentricity, the thickness and the angle of embrace. Five types of test were made on the arches: first, friction coefficient measures were taken on the blocks; then moving the supports horizontally apart and together, and vertically up and down. The comparison of theoretical and experimental results has allowed to emphasize the limits of both of them. Perfect hinges, sharp blocks, exactly symmetric structures, absence of friction, all accepted hypothesis in the theory, can never exist in reality; as a consequence the theoretical numerical results are greater than those measured in the experiments. At the same time the presented methods correctly predicted the final collapse mechanisms for the circular and specially the pointed arches. In the light of the conducted experiences in this study, in terms of modelling, analysis and testing, it is believed that masonry structures deserve great attention in the design and assessment process. Many mistakes can be made regarding the basic assumptions on the constitutive model of the material, the suitable structural modelling, the choice of the seismic action and an effective retrofit techniques. Furthermore, churches are more sensitive to damages than other “conventional” structures for their characteristic typology. The main features of these structures have been drawn throughout this work so that whatever similar building will fairly show the same topics here presented. About the material properties, only experimental campaigns on the structural constituents of the building under study could provide a good characterization. Regarding the suitable analysis types, undoubtedly, a global three-dimensional analysis is necessary to get the general idea of the construction and understand its behaviour. On the other side, a useful quantitative result is the evaluation of the ultimate condition at collapse on bi-dimensional elements. This consideration is also made since the definition of the seismic forces for masonry structures according to different code provisions is not unique. Simplified approaches do prove their appeal. Though some approximations are unavoidably to be made, in the aim of assessing the structural behaviour of ultimate capacity, such techniques seem to provide a very interesting path to follow in the future

Recent investigations on the behaviour of buildings after the loss of a column

Abstract: Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. According to Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most of the cases, no precise practical guidelines on how to achieve this goal are provided. An European RFCS project entitled “Robust structures by joint ductility” has been set up in 2004, for three years, with the aim to provide requirements and practical guidelines allowing to ensure the structural integrity of steel and composite structures under exceptional events through an appropriate robustness. In particular, one substructure test simulating the loss of a column in a composite building will be performed at Liege University. The present paper described first analytical and numerical studies carried out at Liege University as part of this European project. for three years, with the aim to provide requirements and practical guidelines allowing to ensure the structural integrity of steel and composite structures under exceptional events through an appropriate robustness. The robustness is required from the structural system not directly affected by the exceptional event (to avoid the local destruction of the structural element where the event occurs being often not possible). In this process, the ability to redistribute plastically extra forces resulting from the exceptional event is of high importance. This requires from all the structural elements and from the constitutive joints a high degree of plastic deformability under combined bending, shear, ... or axial forces. The partners involved in this project are: − Stuttgart University, Germany; − Liege University, Belgium; − ProfilArbed-Research (PARE) from the Arcelor Group, Luxembourg; − PSP-Prof. Sedlaceck & Partner Technologien, Germany and; − Trento University, Italy. The present article presents the first developments performed at Liege University as part of this European project and is organized as follows: − Section 2 presents the different exceptional events covered within the project and the adopted strategy; − then, first numerical and analytical developments performed at Liege University are described in Section 3 and; − finally, in Section 4, the substructure test to be performed at Liege University is presented. 2 COVERED EXCEPTIONAL EVENTS AND ADOPTED STRATEGY As a general procedure to derive robustness requirements, different structural systems subjected to exceptional events are analytically and numerically investigated within the previously mentioned project in order to see how steel and composite structures work when part of the structure is destroyed as well as how and how far redistribution takes place. Exceptional events have been selected; many could be contemplated, but few preliminary ones have been considered as reference cases to be studied first: 1 loss of a column in an office or residential building frame; 2 loss of a beam in an office or residential building frame; 3 loss of a column in an industrial portal frame; 4 loss of a bracing in an industrial portal frame; 5 loss of a bracing in a car park; 6 unexpected earthquake; 7 unexpected fire. For the five first cases, finite element (FEM) numerical simulations are carried out so as to understand how the structure and its constitutive elements behave and how the redistribution of forces takes place in the unaffected part of the frame. In this process, a special attention will be devoted to the study of the loading sequence inside the joints. As a result of these FEM numerical simulations and associated parametrical studies, simplified behavioural models should be developed and validated; these ones should progressively lead to analytical models, from which requirements to be satisfied by the structural system and by the joints could be derived. Progressively, other exceptional situations should be investigated in the same way and related design requirements should be derived. Possibly similarities between different exceptional events and their corresponding failure modes will be identified and more general requirements are so expected to be formulated. For the six and seventh here-above listed events, the work consists in expressing requirements that structures which have not been explicitly designed for fire and/or seismic actions should fulfil so as to possess a certain amount of robustness against such unexpected extreme situations. In different countries, “good practice” detailing recommendations and conceptual design guidelines exist (for instance for so-called “non-engineered structures”) and the work should therefore consist in gathering and analysing this available material and present it into an adequate format. Within the previously mentioned European project, the analytical and numerical investigations has been shared among the partners: − Trento University is in charge of “event 6” (earthquake); − PARE covers “event 7” (fire); − Stuttgart University studies “event 5” (loss of a bracing in a car park); − Liege University focuses on “events 1 and 3” (loss of a column in office or residential composite building frames and in industrial steel structures) − PSP contributes to the knowledge on “events 1 and 3” by studying 3-D aspects as well as the loss of more than one column; Liege University is in charge of coordinating the whole activity. Also, one of these exceptional events, the loss of a column in a composite structure, is intended to be tested experimentally at Liege University, as part of the project; this will allow to validate the numerical tools used in the preliminary study. Finally, parametrical studies will be carried out numerically for the selected events and robustness requirements will be derived. In the next section, first analytical and numerical investigations performed at Liege University on “Event 1” (loss of a column in an office or residential building frame) are described. 3 LOSS OF A COLUMN IN A BUILDING ANALYTICAL AND NUMERICAL INVESTIGATIONS

Steel rail type pile engine

Abstract: The utility model discloses a steel rail type pile engine, which comprises a main frame, a walking trolley and a walking cart. An A-shaped frame, a capstan engine and an electric control cabinet are connected with the walking trolley, the walking cart is arranged on a ground rail and the walking trolley is arranged on a trolley rail which is arranged on the walking cart. The walking trolley is connected with the lower end of the main frame through a hinge and a pin shaft, the middle part of the main frame and the rear part of the walking trolley are connected by an inclined support rod and the upper end of the main frame is connected with a pulley head. A capstan engine steel cable is connected with a vibration hammer by passing by the pulley head, and the vibration hammer is connected with the upper end of a drainage plate intubation. Therefore, a bulky portal frame is eliminated, steel consumption is reduced and manufacturing cost is lowered. The main frame can be conveniently erected without using a crane when the utility model is installed on a construction site. The utility model has the advantage of convenient and safe operation. Compared with a portal frame type pile engine, efficiency is improved by 16 times. The operation is mainly carried out on the walking cart, so working safety is improved. The utility model can be used for inserting drainage plates or arranging sandbags in areas, such as sea beach, marshland, mudflat, etc.

1 – Lateral buckling of tapered steel members

Abstract: The modern use of plated structures means that the cross-sectional and lengthwise profiles for a given member may be optimized by welding tapered plates together. The first figure of this chapter shows two ways in which a web-tapered member may be manufactured: the first is by welding two flanges to a tapered web plate, while the second shows a diagonal cut through the web of a hot-rolled I-section member, the rotation of the relative portions of the cut member, and its rewelding to produce a tapered profile. The concept of efficient steel design with tapered members is not new, and nowadays web-tapered members of this type find widespread contemporary use in steel portal-frame structures, since the deeper flanged portions may be utilized in the high moment regions (at the portal frame eaves) to economize the use of steel. However, because members with welded plates are relatively slender, their strength is often governed by lateral (or flexural–torsional) buckling.

Inelastic Analysis of Semirigid Frameworks

Abstract: This article presents an efficient method for inelastic analysis of semirigid planar steel frameworks. A compound element comprised of a plastic-hinge element and a semirigid connection element is located at member ends that may potentially undergo inelastic deformation. Nonlinear inelastic flexural behaviour is modeled by an empirical relation between moment and rotation for which the parameters are available from experimental results. A four-parameter model is employed to simulate the nonlinear moment-rotation behaviour of semirigid connections. The member stiffness matrix involving the compound element is expressed explicitly in terms of stiffness degradation factors that vary depending on the loading level. This permits direct account for the combined influence of inelastic and nonlinear connection behaviour on structure stiffness. A semirigid steel portal frame is analyzed to illustrate the proposed analysis method, and the results are compared with those obtained from experiments involving the same frame.

Structural Damage Identification Based on Model Updating

Abstract: This paper presents a new method for structural damage identification based on the finite element (FE) model updating techniques. First, an objective function is defined as minimizing the sum of differences between the experimental and analytical modal data (natural frequencies and mode shapes), which is set as a nonlinear least-squares problem with bound-constrains. The trust-region approach is then used to solve the minimization problem in order to make this optimization process more robust and reliable. In addition, the expansion and weighting of the original objective function are investigated so that the presented method can be well applied into the damage identification of more real structures. Finally, a numerical simulation model of two-story portal frame structure is adopted to evaluate the efficiency of the proposed technique when both the single and multiple damage cases are set up in the model. Some important issues are also discussed in this paper. The illustrated results show that the single and multiple damages on the two-story portal frame structure can be well identified by the proposed method.Copyright © 2006 by ASME

Plastic Design of Cold-Formed Rectangular Hollow Sections

Abstract: This paper summarises a program of testing on cold-formed rectangular hollow section (RHS) members, connections and frames to assess their suitability for plastic design. Firstly, a series of bending tests examined the plate slenderness limits for RHS. It was found that current web slenderness limits are nonconservative, and an alternative set of limits, encompassing flange-web interaction, is put forward. Secondly, connection tests investigated various types of column-rafter knee joints in portal frames. A novel connection, consisting of a fabricated hollow internal sleeve, was found the most suitable for plastic hinge formation. Finally, three large scale portal frame tests were performed. The frame behaviour shows good agreement with the predictions of advanced structural analysis, and plastic collapse mechanisms were able to form in the coldformed portal frames.

Non-Linear Dynamical Response of Steel Portal Frames with Semi-Rigid Connections

Abstract: Traditionally, the steel portal frame design assumes that beam-to-column joints are rigid or pinned Rigid joints, where no relative rotations occur between the connected members, transfer not only substantial bending moments, but also shear and axial forces Alternatively, pinned joints are characterised by an almost free rotation movement between the connected elements preventing the bending moment transmission Despite these facts, it is largely recognised that the great majority of joints does not exhibit such idealised behaviour These joints, called semi-rigid, should be designed according to their actual structural behaviour Considering all these facts one of the main objectives of this investigation is to propose a modelling strategy to represent the dynamical behaviour of semirigid joints under dynamic actions The developed finite element model included geometric nonlinearities and considered the influence of non-linear and hysteretic joint stiffness The updated Lagrangean formulation is used to model the geometric non-linearity The mathematical model calibration was made based on comparisons to semi-rigid tests and other numerical models [1],[2] and proving to be in accordance to them However, it must be emphasized that cautions should be taken on the direct use of the results in structural design The main reasons for this affirmative are related to the occurrence of very important distortions due to the consideration of the semi-rigid joints geometric non-linearity effects on the steel portal frames dynamical response

Improved pile device for examing motor-vehicle

Abstract: The utility model relates to an improved pile examining device for a motor vehicle, which belongs to the technical field of a pile examining device for the motor vehicle. The utility model mainly solves the technical problems that the improved pile examining device for the motor vehicle has compact and firm structure, convenient construction, safety, beautiful appearance and neatness, and can reduce the construction cost of fields. The utility model has the essential technical scheme that supporting bodies 22 at both sides of a rear portal frame (2) form an n shape; a moving cross beam which is parallel with a cross beam of a front portal frame (1) is arranged between the supporting bodies which form the n shape at both sides of the rear portal frame; a dragging mechanisms which dragges the moving cross beam to move backwards and forwards in longitudinal direction is arranged in the top beams of the supporting bodies forming the n shape on the rear portal frame. The device can improve the precision and the accuracy of the long moving of a garage, can omit special floor rails, and can save the construction cost of the fields. The utility model is convenient for construction, installation, maintenance and moving, and is convenient for the water prevention, the dust prevention and the sun prevention of electrical equipment, improving the security of the electrical equipment and the firmness of a mechanical structure, and thus the whole device has the compact and firm structure, and the beautiful appearance.

Second-Order Analysis for Steel Frame Structures with a Distributed Plasticity Numerical Model

Abstract: This paper provides an efficient numeric model of steel frames using second-order distributed plasticity FEM (finite element method). Details of the modeling including element type, mesh discretization, material model, residual stresses, initial geometric imperfections, and boundary conditions are presented. Its validity is verified by several numerical examples. Case studies of Vogel’s portal frame and space steel frames are performed. The ultimate loads obtained from the proposed analysis and Vogel agree well within 2% error. Therefore, the model is accurate and provides benchmark solutions of steel frames using second-order distributed plasticity analysis. The benchmark solutions of the steel frames are useful for the verification of various simplified second-order inelastic analyses. It is observed that the load carrying capacities calculated by the Code for design of Steel Structures (GB50017-2003) method are 20%∼30% conservative when compared with those of the proposed analysis. and using this model the study was carried out on the effects of the nonlinear factors on the behavior of steel frames.

Numerical modelling of the behaviour of a stainless steel portal frame subjected to fire

Abstract: It is known that stainless steel has a better fire performance than carbon steel, which can lead to a growing utilization of this kind of steel in structures. In fact, although more expensive than the carbon steel, structures in stainless steel can be competitive because of its smaller thermal protection need. With the purpose of modelling by Finite Element Method the behaviour of a stainless steel framed structure, without any protection, submitted to fire, has been introduced in the SAFIR program, the material properties of the stainless steel. SAFIR is a finite element program with geometrical and material non-linear analysis, specially developed in the University of Liege for studying structures subjected to fire. The thermal and mechanical properties of the stainless steel, introduced in the SAFIR program are temperature dependent, according to the Eurocode 3. The stress strain relationship, the thermal conductivity and the specific heat are the most important material properties for the structure analysis at high temperatures. These properties in stainless steel are considerable different from carbon steel. The behaviour of the structure will be compared in the two different materials: stainless steel 1.4301 (also known as 304) and carbon steel S235. The benefits of using stainless steel in the fire resistance of the structure, which is 3 times higher than the one