Search results for "BUCKLING"

Network Arches: The World's Lightest Arch Bridges

2012

Summary Network arches have a tensile and a compressive flange with a web consisting of crossing hangers. Some of the hangers cross each other twice. The network can be seen as a very light, simply supported beam. There is little bending. There is a lot of tension in tie and hangers. The arches are well supported by hangers and wind bracing. Thus the buckling strength of the arch is high as long as few hangers relax. That is easiest to prevent when a concrete tie gives extra weight in the tie. The optimal shape of network arches is discussed. In two lane and two track network arches the biggest bending in the tie is usually the transverse bending half way between the arches. The optimal sha…

Optimization and analysis of processes with moving materials subjected to fatigue fracture and instability

2013

We study systems of traveling continuum modeling the web as a thin elastic plate of brittle material, traveling between a system of supports at a constant velocity, and subjected to bending, in-plane tension and small initial cracks. We study crack growth under cyclic in-plane tension and transverse buckling of the web analytically. We seek optimal in-plane tension that maximizes a performance vector function consisting of the number of cycles before fracture, the critical velocity and process effectiveness. The present way of applying optimization in the studies of fracture and stability is new and affords an analytical tool for process analysis. peerReviewed

Longitudinal Flexure as a Method for Determining the Flexural Strength of Composite Materials

2004

A method is presented for determining the flexural strength of composites from tests on pinned specimens in axial compression. This scheme is close to the so-called Euler buckling model, but the load is applied eccentrically, and the bar is bent practically from the beginning of loading. An analytical model is proposed for calculating the flexural stress in longitudinal flexure of a thin bar in the case of large displacements. The problem is solved in elliptic integrals of the first and second kinds. The analytical model shows an excellent agreement with experiments. The results obtained are compared with experimental tension data. A device is also designed for testing composite bars in lon…

RC Columns Strengthened with Steel Angles and Battens: Experimental Results and Design Procedure

2013

In this paper, an analytical model for the design of axially loaded strengthened RC columns with steel angles and battens is presented. Cases of directly loaded and not directly loaded steel angles are considered. The model considers the contribution in confinement pressures caused by transverse battens and steel angles and the contribution in terms of the load-carrying capacity of steel angles subjected to axial force and the bending moment. An experimental investigation on the compressive behavior of eight short, confined, RC columns externally strengthened with steel angles and steel battens with various pitches was carried out, and has been utilized as support for the analytical model. …

Structural Behavior of Telescopic Steel Pipe for a Full-Scale 60 kW Wind Turbine Tower

2020

A simple analytical model, including local effects due to buckling and shear to moment interaction, was developed to pre-dict the load-carrying capacity of CHS tubes under flexure and shear. A finite-element analysis with ABAQUS Code was also conducted for validation of the proposed model. By properly modeling the imperfection effects due to the ovalization of steel tube, a good correlation of the structural response and failure mode was also achieved, and a good correlation with the analytical model was also achieved. Numerical and analytical results were compared with experimental results recently obtained by the author with good agreement. Experimental tests refer to full-scale static te…

Some conventional and unconventional educational column stability Problems

2006

Two interesting problems are considered for enriching the curriculum of the Strength of Materials course, in the light of recently developed functionally graded materials (FGMs), characterized with the smooth variation of the elastic modulus. These are problems associated with buckling of columns with variable flexural rigidity along the axis of the column. A simple semi-inverse method is proposed for determining closed-form solutions of axially inhomogeneous columns. In order for the presentation to be given in one package, the conventional problems are also recapitulated along with the novel ones. The main approach adopted here is the use of the second-order differential equation, instea…

Buckling and post-buckling analysis of cracked stiffened panels via an X-Ritz method

2019

Abstract A multi-domain eXtended Ritz formulation, called X-Ritz, for the analysis of buckling and post-buckling of stiffened panels with cracks is presented. The theoretical framework is based on the First-order Shear Deformation Theory and accounts for von Karman's geometric nonlinearities. The structure is modeled as assembly of plate elements. Penalty techniques are used to fulfill the continuity condition along the edges of contiguous elements and to satisfy essential boundary conditions requirements. The use of an extended set of approximating functions allows to model through-the-thickness cracks and to capture the crack opening and tip singular fields as well as the structural behav…

Analytical and Numerical Methods for the Evaluation of Critical Conditions in Longitudinal Bars of RC Columns

2017

Buckling collapse of reinforcing bars in concrete members is usually observed in framed structures after severe earthquakes. Second order effects modify the compressive response of steel bars, reducing ductility and affecting the post-elastic branch. Literature investigations show that instability can involve more stirrups, or it can be limited to the pitch. If the critical length is not carefully estimated, transverse steel’s failure can be achieved in brittle manner, causing the sudden loss of confinement in the inner concrete. This paper presents the results of a theoretical investigation, aiming to evaluate the reliability of different approaches for calculating critical conditions of l…

Buckling and post-buckling of variable stiffness plates with cutouts by a single-domain Ritz method

2023

Structural components with variable stiffness can provide better performances with respect to classical ones and offer an enlarged design space for their optimization. They are attractive candidates for advanced lightweight structural applications whose functionalities often impose the presence of cutouts that requires accurate and effective analysis for their design. In the present work, a single-domain Ritz formulation is proposed, implemented and validated for the analysis of buckling and post-buckling behaviour of variable stiffness plates with cutouts. The plate model is based on the first-order shear deformation theory with nonlinear von Karman strain–displacement relationships. The p…

Architecture and kinematics of forearc basins and intra-caldera resurgences: new insight from the Paola Basin (western offshore Calabria region) and …

This thesis deals with the patterns of tectonic deformation at different time and spatial scales ranging from tens to millions of years and from one to tens of kilometers, respectively. The study areas are the Campi Flegrei (Campania region, Italy) and Paola Basin (western offshore Calabria region, Italy). The Campi Flegrei and its offshore prolongation, the Pozzuoli Bay, are a laboratory for investigating volcano-tectonic deformations at 1yr-1kyr timescale and 1km spatial scale related to the dynamics of the Neapolitan Yellow Tuff (NYT) caldera and its intra-caldera resurgence. Resurgence is the late stage, long-term uplift of a collapse caldera floor to form a dome-like structure. The com…