1,720,994 research outputs found
Rigid block modelling of historic masonry structures using mathematical programming: a unified formulation for non-linear time history, static pushover and limit equilibrium analysis
No full textA unified formulation is presented for non-linear time history, static pushover and limit analysis of historic masonry structures modelled as 2D assemblages of rigid blocks interacting at no-tension, frictional contact interfaces. The dynamic, incremental static and limit analysis problems are formulated as mathematical programming problems which are equivalent to the equations system governing equilibrium, kinematics and contact failure. Available algorithms from the field of mathematical programming, contact dynamics and limit analysis are used to tackle the contact problems between rigid blocks in a unified framework. To evaluate the accuracy and computational efficiency of the implemented formulation, applications to numerical case studies from the literature are presented. The case studies comprise rigid blocks under earthquake excitation, varying lateral static loads and sliding motion. A set of two leaves wall panels and an arch-pillars system are also analysed to compare failure mechanisms, displacement capacity and magnitudes of lateral loads promoting the collapse
Local Buckling phenomena in built-up cold-formed beams: experimental and numerical investigations
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Numerical Analysis of Local Buckling In Built-Up Cold-Formed Steel Beams Assembled By Laser Welding
No full textLiABlock_3D: A Software Tool for Collapse Mechanism Analysis of Historic Masonry Structures
No full textA rigid block model is proposed for collapse mechanism analysis of three-dimensional historic masonry structures subjected to point live loads, seismic-induced lateral loads and settlements. The model is made of polyhedral rigid blocks interacting at no-tension, frictional contact interfaces and can be used to represent complex assemblages and bond patterns. The formulation and the solution procedure of the underlying limit equilibrium analysis problem were implemented in LiABlock_3D, a MATLAB based tool with Graphical User Interface (GUI). The software was designed to import the geometric model from commercial Computer Aided Design (CAD) tools, thus allowing high flexibility of structural configurations and masonry patterns. The graphical interface is also used to define material properties as well as boundary and loading conditions. Numerical and experimental case studies from the literature were analyzed to show the ability of the model developed in predicting the collapse behavior of a variety of structural typologies. Those include arches, vaults, and domes under vertical and horizontal live loads and spreading supports. A two-story masonry building with a barrel vault at first level is also analyzed under variable lateral loads and support movement. Potentialities and limitations of the proposed formulation and tool are discussed on the basis of the results obtained and also in terms of computational efficiency
Studio numerico-sperimentale di sistemi di connessione innovativi per membrature cold-formed
No full textA simplified multi-performance approach to life-cycle assessment of steel structures
No full textThis paper presents an application of a simplified assessment approach to steel structures which takes into account sustainability requirements. The proposed approach is based on a time-dependent, multi-performance-based design methodology. The simplified procedure is organized in three main steps concerning the environmental conceptual design, the ordinary structural design and the life-cycle analysis devoted to defining service life scenarios in order to assess the structural, economic and environmental performances of structures during their entire life-cycle. Three different seismic-resistant steel structural typologies are designed for a multi-storey residential building and compared in terms of sustainability. Those comprise Moment Resisting Frames (MRF), Concentrically Braced Frames (CBF) with removable Chevron braces and Eccentrically Braced Frames (EBF) with removable shear links. The structural, environmental and economic performances of the three examined design options are assessed and compared in order to evaluate their sustainable potentialities and criticalities for two design scenarios, namely an ordinary condition characterized by an expected deterioration and an exceptional case in which a seismic event hits the structures during their service life
The prediction of collapse mechanisms for masonry structures affected by ground movements using Rigid Block Limit Analysis
No full textMasonry structures belonged to the Cultural Heritage suffered severe damages in the last decays due to the action of the settlementinduced ground movements. The researchers have been developing numerical tools for the vulnerability analysis and assessment of masonry structures subjected to settlements. Continuous, discrete and rigid block mod els were proposed in literature. The analysis of both local or global failure modes due to settlement is a still debated topic, involving several questions relate d to the modelling techniques and to the investigation of the parameters which affect the masonry behaviour against foundation movements. In this framework, the paper focuses on a numerical approach for the settlement analysis based on the rigid block limit analysis. The Italian Code (NTC 2018) also suggests linear kinematic approach for the seismic-induced collapse mechanisms analysis. In such a formulation, the structure is modelled as a collection of polyhedral rigid blocks assuming frictional contact interfac es with infinite compressive strength and zero tensile strength and neglecting the mortar contribution. Originally formulated for the inplane and out-of-plane mechanisms analysis, the numerical formulation was recently improved in order to analy ze blockystructures subjected to uniform settlement. Numerical case study of a monumental masonry church façade subjected to uniform settlement at the base was presented in this paper aiming at testing the numerical procedure. The results were discussed to evaluate the software capability and accuracy in the settlement-induced collapse mechanisms prediction
3D Rigid Block Limit Analysis of a Masonry Cross Vault Subjected to Shaking Table Tests
No full textThis paper presents the results of a numerical study on a brick masonry cross vault that was tested on a shaking table, on a scale of 1:1. The study was part of the blind prediction competition organized within the activities of the SERA-AIMS project “Seismic Response of Masonry Cross Vaults: Shaking table tests and numerical validations”. The main objective of the blind prediction competition was to compare various numerical techniques. Among others, the one presented in this paper is based on 3D rigid block limit analysis. In the numerical model, the masonry units of the cross vault are modeled with rigid blocks interacting at no tension-frictional interfaces. A simple iterative procedure is used to take into account the non-associative behavior in sliding failure. Preliminary analyses carried out at the blind prediction competition stage as well as post-diction studies, after the experimental tests, are presented. The paper emphasizes the differences between the pre-diction and post-diction phases to highlight the improvements made during the numerical investigation. The study shows the influence of support and action modeling as well as of friction coefficient on the failure mechanisms and force capacity
Blind-test numerical simulation of shake-table tests on three-leaf masonry walls: An application of LIA block_3D
No full textThese simulations deal with the application of LiABlock_3D, a rapid computational tool developed by the Authors [1], for limit analysis of masonry structures subjected to point live loads, seismic induced lateral loads and moving supports. The software was previously validated against several experimental tests available in the scientific literature mainly concerning small scale specimens of masonry walls subjected to lateral loads and settlement. The three-leaf masonry walls of the numerical contest will be represented as 3D assemblages of rigid blocks interacting at no-tension, frictional contact interfaces. LiABlock_3D will provide as outputs the computed collapse load and the plot of the corresponding failure mechanism
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