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Previous studies on stressed skin effect of industrial steel buildings showed discrepancies between the ECCS formulae and experimental results. To clarify the discrepancies full-scale experimental test program was planned and executed by the Budapest University of Technology and Economics, Department of Structural Engineering. The aims of the full-...
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The behavior of steel bolted connections is a complex structural problem which involves various factors such as material nonlinearity, large deformation and contact. The investigation of this behavior is one of challenging subjects in structural analyses. Unlike other structural modelling, the connections of bolted structures involve a large number...
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... The thick diaphragm had a significant influence on the distortional warping deformations and stresses (Ren et al., 2019). Not only the bridges need the intermediate diaphragms, steel portal frames (Lendvai et al., 2018), floors systems (Rezaeian et al., 2020), unpropped circular diaphragm wall (Tan and Wang, 2015) and wood diaphragms (Zhang et al., 2016) are also indispensable. ...
To solve the problem of insufficient transverse connection of T-girder bridges, this paper investigated the strengthening method of two composite trusses symmetrically installed in mid-span. The composite truss included two top plates, four diagonal braces, and one horizontal brace. An experimental investigation was carried out to study the mechanical properties of reinforced concrete T-girder using single-point loading method under four load cases. The experimental results showed that the maximum transverse stiffness of T-girder specimens strengthened with composite trusses improved by 12.4% compared with control beams. Simultaneously, it had an excellent restraining effect on the cracks development. The maximum percentage decrease in the deflection corresponding to the maximum load when the reinforced concrete T-girder strengthened with composite trusses over the control beam of up to 39.7 was observed. In addition, the load transverse distribution coefficient was investigated according to rigid-jointed slab (girder) method. The composite trusses were chosen as intermediate diaphragm to calculate moment of inertia. The analytical model was in an accurate with the experimental result under the same loading condition. The optimize spacing of composite trusses was given from 600 mm ( L/10) to 1200 mm ( L/5), and thickness of top plate was 30 mm when the load transverse distribution coefficient was homogeneously distributed. Finally, a three-dimensional finite element model was used to evaluate the effectiveness of composite trusses.
... These are probably some of the reasons for the increasing interest of the researchers in stressed-skin actions. The improvements to the analytical procedures are investigated, e.g., new factors affecting stiffness of the diaphragms but neglected in the procedures and analyses of schemes of the fasteners, e.g., the lack of seam fasteners [3][4][5][6], and schemes known from practice but not included in recommendations [7,8]. ...
... Moreover, strains were measured by SG (for the location of the SG; see point 2.3), leading to the corresponding stresses: SG1 and SG5-stresses in the direction perpendicular to the corrugation (top and bottom side of the sheeting respectively) and SIG_1 and SIG_2-the principal stresses linked with the outcomes of strain gauge rosette; see Figure 7. Note that the stresses related to profile distortion (in the location of strain gauges SG1 and SG5) start to increase earlier and become much greater than the stresses related to global shear of the panel (in the location of strain gauges SG2, 3,4). It confirms the prediction that in this variant of panel geometry (relatively high trapezoidal sheeting compared to the panel planar dimensions), the profile distortion dominates the shear strain. ...
In stressed-skin design, the cladding stiffening effect on structures is taken into account. However, the “traditional” design is more usual, wherein this effect is neglected. Even if the diaphragm actions are not regarded, in particular cases such as big sheds (and others), the parasitic (unwanted) stressed-skin action may occur with the result of leakage or even failure. The structures of this kind have already been built. Thus, an important question arises: How can one assess them if there is a need to correct or redesign them? What kind of non-destructive approach can be used to achieve that? Experimental tests of small-scale shear panels made of trapezoidal sheeting were designed in order to observe the behaviour of the diaphragm under increasing and repeated load. The tests were oriented toward force–displacement relations and strains in selected areas of the sheeting. The results revealed nonlinear, hysteretic force–displacement behaviour of the panel and the occurrence of the persistent deflections and stresses which remain even after the unloading. The relation among the stresses, force–displacement paths and modes of failure can be potentially used in monitoring systems of existing buildings in terms of parasitic stressed-skin action.
... After the numerical study full-scale experimental research project was performed in 2014, where below findings were obtained [23][24][25]: ...
... In the next steps of research, an extensive full-scale experimental program was conducted at the Budapest University of Technology and Economics [23][24][25], which served as a basis for further investigation of current formulae. In the test series trough fixed constructions were investigated, as this type of configuration is used commonly in industrial practice in Hungary. ...
Lightweight roof and wall structural systems are widely used for cladding of steel portal frames. It is a well-known fact, that assembled systems of profiled sheeting and purlins show significant stiffness to in-plane loads, which action is referred to as stressed skin effect. This research aimed to investigate the influencing parameters of stressed skin effect in those nonstandard diaphragm constructions, in which seam fasteners are omitted.
The focus of this paper is on the results of an experimental test programme, that investigated the stiffness of nonstandard, 3.00 x 3.00 m sized diaphragm configurations for in-plane static load. The experimental results are compared against analytical results derived from calculated shear flexibilities according to current ECCS formulae. Upon experimental test results, a verified and validated numerical model is developed, and the range of experimental tests is extended by numerical simulations. The conclusions of numerical analyses demonstrated, that the effect of purlin section height and thickness is not followed by current ECCS provisions.
The intended purpose of the research is to develop the current ECCS stressed skin design formulae to incorporate nonstandard diaphragm constructions, which are commonly used in industrial practice in Europe. The innovative feature of formulae improvement is to comprise the effect of those parameters, which are influencing shear flexibility and are not addressed in the current ECCS design methodology. Upon experimental, analytical and numerical results a modification is presented to current formulae of shear flexibility, which gives a better approach in nonstandard cases.
In construction industry, the usage of structural steel in the building has increased and it can also be recycled in the future. The structural members in tall industrial steel buildings like column occupies more space due to larger section size which causes obstruction. In order to achieve economical section size for tall industrial steel building, spacing of columns is ideal, to be chosen with trial and error method for assessing the distance of center to center of column. The bracings system is provided in vertical plane, which will be tied to the major axis of column above certain height in nonusable space and also bracings system in horizontal plane, where both the planes act as a diaphragm. Due to connection in the major axis of column, section reduction will be possible by distribution of forces equally. The members used in bracing system will be of higher section due to distribution of more forces. For this the members of different shapes are used, to find the optimum section for the bracing members. This helps in optimizing the section size of the tall steel building.KeywordsDiaphragm actionsShape of structural memberBracing techniques
In the side supporting structure of a precipitator casing, the skeleton column is sometimes designed as a composite section composed of double H-shaped steel limbs and connecting wallboard. Column buckling is characterized by its special section and the stressed skin effect from wallboard. The influence of initial imperfections and structural parameters on column stability was investigated using the nonlinear finite element method. The residual stress has a slight adverse effect on column stability. The buckling modes can be categorized into two types: 1) buckling of connecting wallboard; 2) simultaneous buckling of connecting wallboard and flexural-torsional buckling of H-shaped limbs in top segment. Column stability significantly increases with increasing connecting wallboard thickness, decreasing connecting wallboard width, and decreasing distance between the connecting wallboard and the rear flange of H-shaped limbs. The structural parameters of the wallboard, angle steel stiffeners, and transverse brace interval have no noticeable effect. Column stability slightly increases with a decrease in the width-to-thickness ratio of flange, the height-to-thickness ratio of web, and torsional slenderness ratio. Based on the simulation results, a buckling capacity calculation recommendation was developed for an axial compressive double-limb column, which is important for the design of heavily stressed double-limb columns in box-type structures.
This paper proposes a novel cold-formed portal framing system that comprises tapered box members formed from two cold-formed nested channel sections. The proposed method possesses structural and non-structural advantages such as improved seismic performance, enhanced building hygiene through bird and dust resistance, further corrosion resistance, and aesthetic improvement as a result of fly bracing removal. The novelty of the box member lies in the tapering ability of the section, leading to material and paint savings. In order to examine the failure mechanisms and structural performance of the tapered box portal frame and investigate the adequacy of the design method, two full-scale portal frames with an 18.16m span were built and tested to failure under two common loading scenarios. The first was lateral cyclic loading into the inelastic range in conjunction with a vertically acting permanent load. The possibility of ductile plastic hinge formation in a severe earthquake was investigated by lateral cyclic testing. The second was vertical loading to failure. A novel economic loading setup was used to apply the gravity load on the frame. For seismic design of this section type, slenderness limits are proposed for seismic applications along with the design ductility. A rotational stiffness value for a nominally pinned portal frame column base was also suggested in this study.
Steel housing solutions made of thin-walled cold-formed steel profiles (CFS) appear to be competitive in seismic areas because of their light weight and the associated reduced mass. This non-negligible advantage on top of their competitive costs and the ease with which they are built have made this type of building popular. In addition, several in-depth studies into the lateral response of shear walls have been carried out in recent years in order to analyse the potential of these structural systems. However, little attention has been paid to the behaviour of floor diaphragms and to their contribution to the overall building response. In an attempt to address this issue, the University of Trento has conducted research into the response of CFS floor systems subjected to in-plane shear loading, as part of a broader research project aimed at the development of a residential building system made of CFS profiles. This involved testing six types of floors featuring two different beam systems and three different types of deck, using monotonic and cyclic protocols. The results of the experiments provide a background to FE model calibration, simulating both the floor components and the whole floor. In this paper, the main features and outcomes of these tests are presented and discussed.
This paper reports the development, numerical implementation and practical application of a novel/improved approach to perform the buckling analysis of braced/restrained cold-formed steel members by means of Generalised Beam Theory (GBT). The novelty consists of a cross-section analysis procedure that incorporates elastic restraints and, therefore, leads to a set of constrained deformation modes with clear structural meaning for the member under consideration. The potential of the developed GBT-based approach is illustrated by presenting and discussing numerical results concerning cold-formed steel (i) purlins restrained by sheeting and (ii) studs braced by sheathing. For validation and assessment purposes, several GBT-based results are compared with values provided by the programs GBTul2.0 (conventional GBT), CUFSM (finite strip method) and/or Ansys (shell finite elements). It is shown that the proposed GBT-based approach is much more efficient than the conventional one, as it offers the possibility of obtaining accurate buckling results with very few (constrained) deformation modes – this feature makes it possible to derive semi-analytical formulae to calculate critical buckling loadings of braced/restrained members. This capability is used in this work to derive GBT-based semi-analytical formulae providing critical length and buckling loading estimates for cold-formed steel purlins and studs restrained by panels (sheeting or sheathing).
