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In recent years, the use of partially concrete-filled steel tubular (PCFST) columns has been considered due to their cost-effectiveness and reduction of structural weight in bridge piers and building columns. One of the critical discussions about these columns is their impact resistance. In this article, the dynamic response of hollow and PCFST columns with elliptical cross-section under simultaneous loading of static axial compressive load and lateral impact load is presented using finite element modeling in ABAQUS software (FEA). To ensure the accuracy of the numerical modeling, the analysis results are compared with the results of previous works. The effects of different parameters such as impact velocity, the height of the impact location, the impact direction, the impact block mass, the size and shape of the impact block are investigated in this paper. The results of the numerical analysis showed that the partially filled specimens had better performance than the hollow specimens. The changes in impact direction and impact block mass parameters have a significant effect on the failure of the columns, especially when they are under high impact velocity. Changing the impact velocity significantly affects the impact resistance of specimens. However, the size and shape of the impact block did not have a significant effect on the displacement of the column against the impact loading. [ABSTRACT FROM AUTHOR]

The traditional roll position adjustment system on the one-time forming of cold-formed steel unit is not only inefficient, but also has poor stability. Moreover, the error of the roll parameters measured by the manual experience and the caliper measured is very large, which leads to low yield of product and high cost labor. In order to solve the above problems, this paper designs a set of roll position automatic adjustment system that can predict roll parameters. The automatic control technology, sensor technology and industrial communication technology are applied to this system and the high performance PLC controller is used as control core. Three-phase asynchronous motors are controlled by PLC(S7-1500) to drive gear connected with reducer and coupling so as to drive rolls connected with the upper and lower horizontal axis to move. In this paper, the PCA-BP algorithm is used to train the roller parameters prediction model so that the roller parameters of a given model of square-tube are predicted. Then the parameters of the new type of square-tube roll distribution are predicted, and the simulation results are compared with the actual production results while the automatic adjustment was completed. The field application shows that the prediction of square-tube roller parameters based on PCA-BP algorithm is more effective than manual measurement, and the whole system is simple in operation, stable in operation and the time used is less, the maximum measuring error of the roll displacement of the system is only ± 2 mm. The system can predict the corresponding roller parameters according to the specifications of the new model square-tube, and automatically complete the adjustment. The system not only improves the adjustment speed and accuracy, but also avoids the waste of manpower so that business productivity has been greatly improved. [ABSTRACT FROM AUTHOR]

This paper presents a computational methodology to compute the critical buckling stress of built-up cold-formed steel columns joined with discrete fasteners. The fasteners are modeled as three-dimensional beam elements, and their effect is integrated into the spline finite strip framework, evolving the compound strip methodology. Although this technique has been presented in the literature, this paper presents yet another robust framework for the buckling load evaluation of compound cold-formed steel columns with arbitrarily located fasteners. The proposed framework is applied to study the effect of fasteners on the formation of local, distortional, and global buckling modes of built-up section and a comparison is drawn with the buckling behavior of a single section. In this study, the proposed formulations are also used to get insights into the stability behavior of single-span and multi-span compound cold-formed steel columns in the presence of (i) fasteners with varied spacings with respect to span and (ii) the presence of the additional restraining system such as wall panels. For different buckling modes, a significant increment in buckling stress for a built-up section from a single section is observed when the fastener spacing is kept less than the critical buckling half-wavelength of the respective buckling modes. The study on the effect of wall panels shows that in comparison to unsheathed wall studs, the sheathed wall studs that produce additional constraints lead to the elimination of the global buckling deformations. The proposed formulations are simple, yet rigorous and have been validated using finite element-based numerical results. [ABSTRACT FROM AUTHOR]

Perforated cold-formed steel (PCFS) beams are regarded as an economical option for steel construction industry owing to its various advantages. They can provide access for the facilities like electric wires and pipelines to penetrate the web so that extra building space could be saved. However, the web openings might change the web stress distribution as well as reduce the cross-sectional properties, which make the PCFS beams more susceptible to buckling and may have effect on their load-bearing capacity. In this paper, a simplified spring model was proposed based on the use of energy method, to predict the critical moment of lateral-torsional buckling of PCFS channel beams with circular holes in web subject to pure bending. The effect of hole sizes and lateral restraint at the tension flange was examined by using the derived analytical solution. In addition, eigenvalue buckling analysis was conducted by using finite-element package ANSYS to validate the accuracy of the proposed analytical model. The results demonstrated that the proposed analytical solution was reliable and the critical moment predicted can be used for the extension of DSM formulae for the design of PCFS beams when considering the failure caused by lateral-torsional buckling of the beams. [ABSTRACT FROM AUTHOR]

The current cold-formed steel (CFS) wall is limited to the low-rise cold-formed thin-walled steel structure, which is inappropriate for multi-story constructions due to its low shear resistance and poor corrosion resistance of outer sheathing board. Therefore, a new composite wall of CFS frame sheathing with concrete and plasterboard was proposed, the cast-in situ concrete layer was used for the outer surface in response to the needs of corrosion resistance, and the plasterboard was utilized for the inner surface to reduce weight. This paper presented a quasi-static test on the seismic behavior of one CFS wall and three composite-walls' sheathings with concrete and plasterboard to obtain different failure modes and investigate the influence of different sheathing and opening sizes. Combined with the finite element model, a large parametric study of composite walls was conducted to analyze the impact of load ratio, reinforcement ratio, sheathing board, and concrete and steel strength. Test and finite element analysis (FEA) results demonstrate that the seismic performance of composite walls with concrete and plasterboard is satisfactory considering their shear strength, ductility, and energy dissipation. Load ratio, opening size, and reinforcement ratio significantly affect the seismic performance of the composite wall, while the concrete and steel strength and sheathing board have minimal effects. The seismic design suggestions of composite walls are given based on this study. [ABSTRACT FROM AUTHOR]

This paper reports the results of an investigation on the use of Generalized Beam Theory (GBT) to assess the buckling and vibration behaviors of thin-walled members and frames built from cold-formed steel circular hollow section (CHS) profiles. Initially, the concepts and procedures involved in performing GBT buckling and vibration analyses are presented, paying particular attention to the derivation of the mass tensors that account for the influence of the inertia forces. Then, the formulation, numerical implementation and validation of a GBT-based beam finite element for isolated members are described. Next, the determination of the frame linear stiffness, geometric stiffness and mass matrices, which incorporate the influence of the frame joints, is addressed. Finally, in order to illustrate the application and capabilities of the proposed GBT finite element formulation, numerical results are presented and discussed - they concern the buckling and vibration behaviors of an "L-shaped" frame. For validation purposes, most GBT-based results are compared with values yielded by shell finite element analyses carried out in the code ANSYS. [ABSTRACT FROM AUTHOR]

The importance of allowing for the many different types of structural interaction that have an effect on the performance of light gauge members when used in practical situations is emphasized. A distinction is drawn between internal interactions involving the various plate elements of the steel profiles and external interactions involving the other components in the system. Although full-scale testing of representative systems can capture this behavior, the costs involved make this an impractical general basis for design; codified methods generally consider only isolated plates within members and isolated members within systems, thereby neglecting the potentially beneficial effects of both forms of interaction. Properly used, modern methods of numerical analysis offer the potential to systematically allow for both forms of interaction — provided the numerical models used have been adequately validated against suitable tests. The use of such an approach is explained and illustrated for three commonly used structural systems: roof purlins, floor beams, and columns in stud walls. In each case, it is shown that, provided sufficient care is taken, the numerical approach can yield accurate predictions of the observed test behavior. The subsequently generated large portfolio of numerical results can then provide clear insights into the exact nature of the various interactions and, thus, form the basis for more realistic design approaches that are both more accurate in their predictions and which lead to more economic designs. Building on this, modifying existing arrangements so as to yield superior performance through specific modifications is now possible. Two such examples, one in which improved interconnection between the components in a system is investigated and a second in which prestressing is shown to provide substantial enhancement for relatively small and simple changes, are presented. [ABSTRACT FROM AUTHOR]

In order to solve the existing problems of inefficiency, instability, inaccuracy and low degree of automation, the roll position automatic adjustment system is designed for the one-time forming of cold-formed steel unit. The automatic control technology, sensor technology, communication technology and human-machine interface (HMI) configuration technology are applied to this system and the high-performance PLC controller is used as control core. Triple-phase asynchronous motors are controlled by PLC (S7-1500) to drive the gear connected with reducer and coupling so as to drive the rolls connected with the upper and lower horizontal axes to move. The osiswitch is used to calibrate zero position and the closed-loop control system is constructed by analyzing and feedbacking the signal of the sensor. In this way the system can improve the roll position adjustment accuracy. The practical applications show that the whole system is simple, stable and efficient and the maximum detection error of roller displacement is only 2mm. The system can automatically call the corresponding roll position data according to the specification of the steel pipe. The system not only improves the adjustment speed and accuracy, but also avoids the waste of manpower so that the enterprise production efficiency can be greatly improved. Meanwhile, in order to carry out efficient management of the unit, the unit's health management system was used to analyze and monitor the status of the unit in real-time. [ABSTRACT FROM AUTHOR]

The investigation attempts to adapt a beam finite element procedure based on the Generalized Beam Theory (GBT) to the analysis of perforated columns. The presence of perforations is taken into account through the use of two beam elements with different properties for the non-perforated and perforated parts of the member. Each part is meshed with its corresponding finite element and, afterwards, they are linked by means of constraint equations. Linear buckling analyses on steel storage rack columns are carried out to demonstrate how the proposed procedure should be applied. Some practical issues are discussed, such as the GBT deformation modes to be included in the analyses, or the optimum finite element discretization. The resulting buckling loads are validated by comparison with the values obtained in analyses performed using shell finite element models. Finally, it is verified that the buckling loads produced with the proposed method are rather accurate. [ABSTRACT FROM AUTHOR]