Search results for "Steel frame"
showing 10 items of 10 documents
Optimal design of steel frames accounting for buckling
2013
A formulation of a special design problem devoted to elastic perfectly plastic steel frame structures subjected to different combinations of static and dynamic loads is presented. In particular, a minimum volume design problem formulation is presented and the structure is designed to be able to elastically behave for the assigned fixed loads, to elastically shakedown in presence of serviceability load conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and ultimate seismic loadings as well as of fixed and wind actions. The actions that the structure must suffer are evaluated by making reference to the actual Italian seismic code. The dynamic respon…
Comparison between unrestricted dynamic shakedown design and a new probabilistic approach for structures under seismic loadings
2014
The paper concerns a study related to the comparison between two different approaches utilized for the formulation of an optimal shakedown design problem for elastic plastic frame structures subjected to a combination of fixed and seismic loading. The first formulation utilizes the unrestricted dynamic shakedown theory, while the second one is based on a new probabilistic approach. The comparison is effected in terms of mathematical formulations, in terms of adopted loading models and in terms of numerical results. The performed applications are related to plane steel frames.
Iterative Optimal Design of Special Moment Resisting Devices for Steel Frames
2021
Abstract The present paper proposes an iterative procedure devoted to reaching the optimal design of an innovative, recently proposed, moment resisting device. This special device, called Limited Resistance Plastic Device (LRPD), can be utilized, as an example, to equip a steel frame when it is required that the frame must be designed to substitute a masonry panel, i.e., it must be characterized by a structural behaviour as close as possible to the one of the replaced masonry wall. This purpose can be reached by designing the relevant frame imposing appropriate constraints on the elastic stiffness and on the limit resistance. The result can be obtained just by ensuring that the elastic stif…
Targeted steel frames by means of innovative moment resisting connections
2021
Abstract The present paper proposes the use of stepped cross section devices on steel frames aiming at reproducing a pre-established target push-over curve. To this aim a Limited Resistance Plastic Device (LRPD) to be inserted along selected structural members is proposed. The following two main specific features for LRPD are required: any elastic flexural stiffness variation of the original selected member must be avoided; an ultimate plastic bending moment value equal to an assigned percentage of the original limit resistance value must be ensured. Steel frames equipped with LRPD are modeled by means of an extension of a recently proposed Fibre Smart Displacement Based (FSDB) beam element…
Bounds on transient phase plastic deformations in optimal design of steel frames subjected to cyclic loads
2009
A minimum volume multicriterion design of elastic perfectly plastic steel frames subjected to a combination of quasi-static fixed and cyclic loads, bounding the transient phase plastic deformations, is proposed. The problem is formulated according to a plastic shakedown criterion, so that incremental and instantaneous collapse are certainly prevented when the frame is subjected to very strongly amplified cyclic loads. The further condition that the structure must also behave elastically in serviceability conditions is imposed. Since the steady-state loading history is known it is possible to directly bound the steady-state plastic deformations. By applying a suitable own bounding theorem, i…
Fixed strength and stiffness hinges for steel frames
2017
A new type of device able to connect steel beam elements is proposed. Specifically, the device is designed in such a way that the required bending stiffness and limit resistance can be independently imposed. To this goal, the device is realized as a "sandwich" section whose wings possess a particular geometry able to guarantee the required characteristics. Further technological requirement is that the device has to engage plan dimensions equal to those of the elements to which it is connected. The procedure to design the device is presented in the paper with reference to a simple plane steel portal constituted by appropriate profiles in such a way it behaves following an assigned force/disp…
A multicriterion design of steel frames with shakedown constraints
2006
The minimum volume design of elastic perfectly plastic steel frames subjected to fixed and cyclic loads is searched in such a way that the structure remains in elastic field in serviceability conditions, while it is subjected to alternating plasticity under very strong cyclic actions, incremental and instantaneous collapse being prevented. The problem is faced on the grounds of a statical and a kinematical approach. The Kuhn-Tucker conditions of the two problems prove that they are each one the dual of the other and provide useful pieces of information about the structural behaviour. Numerical applications confirm the theoretical expectations: optimal designs turn out to be quite light, wit…
Structural Design of Frames Able to Prevent Element Buckling
2012
Two formulations of a special multicriterion optimal design problem devoted to elastic perfectly plastic steel frame structures subjected to different combinations of static and dynamic loads are presented. In particular, two minimum volume design problem formulations are proposed: in the first one the structure is designed so as to be able to elastically behave for the assigned fixed loads, to elastically shakedown for serviceability seismic load conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and ultimate seismic loadings; in the second one the structure must also satisfy further appropriate constraints related to element buckling. The action…
Design and manufacturing feasibility of ITER TBM Frame and Dummy TBMs
2016
Abstract The operation and test of mock-ups of tritium breeding blankets relevant for a future commercial reactor is one of the goals of the ITER machine. To accomplish this goal, mock-ups of breeding blankets, called Test Blanket Modules (TBMs), are installed in three ITER equatorial ports. Each TBM and the associated shield form a TBM-set that is mechanically attached to a steel frame called TBM Frame. A Frame and two TBM-Sets form a TBM Port Plug (TBM PP). The ITER Organization is responsible for the design and manufacture of the TBM Frames and of the Dummy TBMs that could replace the TBM-sets in case they were not available. This paper describes the recent results of the design supporti…
Optimal design of elastic plastic frames accounting for seismic protection devices
2013
The optimal design of elastic perfectly plastic steel frames with or without suitable protection devices and subjected to static as well as seismic loadings is studied. Two minimum volume problem formulations are proposed, on the grounds of the so-called statical approach, accounting for three different resistance limits: the purely elastic limit, the (elastic) shakedown limit and the instantaneous collapse limit. The adopted load combinations are characterized by the presence of fixed loads, of quasi-static perfect cyclic loads and dynamic (seismic) loads. The linear elastic effects of the dynamic actions are studied by utilizing a modal technique. The proposed treatment is referred to the…