Topic
Portal frame
About: Portal frame is a research topic. Over the lifetime, 1778 publications have been published within this topic receiving 7210 citations.
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TL;DR: In this article, a simple formula for predicting the horizontal capacity of masonry portals is proposed and discussed, and closed form expressions for the multipliers for each of them have been derived.
27 citations
TL;DR: In this paper, the authors present a practical method of the discrete minimum weight design of steel structures based on a concept of removal of the redundant material by successive diminishing of the size of the least stressed member.
Abstract: The paper presents a practical method of the discrete minimum weight design of steel structures. It is based on a concept of removal of the redundant material by successive diminishing of the size of the least stressed member. It is assumed that the member sizes are available from the European Steel Profiles Catalogues, and the design constraints are given by the rules of the code EC3 for nonsway buildings. Two numerical examples are presented: the classical benchmark problem of a ten-bar truss made of circular hollow sections (24 element catalogue, buckling taken into account) and a portal frame made of HEB sections with broad parallel flanges (11 element catalogue). The proposed method gives, after a reasonable calculation time, a very good approach to the exact optimum solution.
27 citations
TL;DR: In this article, a method of determining the optimum joint detail for the eaves and the apex joints is described, and it is demonstrated that careful selection of the joint detail can result in as much as a 25% increase in efficiency of the frame.
Abstract: In cold-formed steel portal framing systems that use bolted moment connections, formed through brackets, for the eaves and apex joints, it is well-known that the joints are semi-rigid, have finite connection-lengths and limited moment capacity. For such frames, it is therefore necessary for these joint effects to be taken into account when conducting frame design and analysis. However, as the semi-rigidity and the finite connection-lengths of each joint influence the bending moment distribution as well as the deflected profile of the frame, the joint detail for the eaves and the apex should not be designed independently of the frame. In this paper, a method of determining the optimum joint detail is described. It is demonstrated that careful selection of the joint detail can result in as much as a 25% increase in efficiency of the frame. Including joint effects explicitly into the design process provides better opportunities to devise the most appropriate balance between joints and member properties and t...
27 citations
TL;DR: In this paper, a trust region approach is employed to make the optimization process more robust and reliable, and the relative weighting scheme between different parts in the objective function is also investigated.
Abstract: This paper proposed a practical damage detection method for frame structures based on finite element model-updating techniques. An objective function is defined as minimizing the discrepancies between the experimental and analytical modal parameters (namely, natural frequencies and mode shapes), which is set as a nonlinear least-squares problem with bound constraints. Unlike the commonly used line-search methods, the trust-region approach, a simple yet very powerful concept for minimization, is employed in order to make the optimization process more robust and reliable. Noting the objective function may sometimes be underdetermined for complex structures due to a relatively larger number of potential damaged elements, this paper attempts to propose a simple and convenient solution by expanding the original objective function. Moreover, the relative weighting scheme between different parts in the objective function is also investigated. One numerical two-story portal frame structure and two laboratory-tested frame structures, including a simple three-story steel frame structure and a more complex frame structure with bolted joints, are all adopted to evaluate the efficiency of the proposed technique. Some important issues about the application of the proposed method are also discussed in this paper.
27 citations
TL;DR: In this paper, a reinforced concrete portal frame was constructed under gravity and severe earthquake conditions, where the beam was subjected to constant vertical loads while a cyclic lateral load was applied to the unit.
Abstract: To study the behaviour of multistorey building frames under gravity and severe earthquake conditions a reinforced concrete portal frame was constructed. The beam was subjected to constant vertical loads while a cyclic lateral load was applied to the unit. Negative moment plastic hinges formed at the column faces while the positive moment hinges were located in the span. The rotations generated by each inelastic displacement accumulated. This placed high rotational demands on the plastic hinges, which reduced the overall ductile behaviour compared with that observed in typical beam-column sub-assembly tests. The high rotations caused the beam to grow in length.
26 citations