Search results for "stiffne"

Analysis of infilled frames using A coupled finite element and boundary element solution scheme

1988

The behaviour of infilled frames subjected to horizontal loads is analysed by an iterative numerical procedure. The stiffness of the structural system is determined with variations in geometrical and mechanical characteristics. The analysis is carried out utilizing the boundary element method (BEM) for the infill and opportunely dividing the frame into finite elements, so as to transform the mutual interactions of the two subsystems into stresses distributed along the boundary for the infill and into nodal actions for the frame. This makes it possible to take into account the separation arising between the two substructures when mutual tensile stresses are involved. At first, infills withou…

2021

Background Vascular alterations induced by antineoplastic treatment might be considered as a possible underlying mechanism of increased cardiovascular sequelae in childhood cancer survivors (CCSs). We aimed to evaluate arterial stiffness among long‐term CCSs and to compare the data against a population‐based sample. Methods and Results Arterial stiffness was assessed by digital photoplethysmography (stiffness index; m/s) among 1002 participants of the CVSS (Cardiac and Vascular Late Sequelae in Long‐Term Survivors of Childhood Cancer) study, diagnosed with neoplasia (1980–1990) before an age of 15 years. A population‐based sample from the GHS (Gutenberg Health Study) (n=5252) was investiga…

Optimal Design of New Steel Connections

2018

The Limited Resistance Rigid Perfectly Plastic Hinge (LRPH) are special steel connections mainly usable to join beam elements of plane or spatial steel frames. The fundamental characteristics of these devices are the mutual independence of their own resistance and stiffness features as well as the respect of assigned constraints related to the elastic and limit behaviour of the joined elements. Within the frame structural scheme, the device plays the role of a rigid perfectly plastic hinge, constituted by a suitably sized sandwich section. The efficient use of the LRPH in the relevant frame depends on the appropriate design of the device geometry. In the present paper, a new approach devote…

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…

On the Post-Elastic Behavior of LRPH Connections

2019

The paper concerns the study of the post-elastic behavior of a recently proposed innovative device, named Limited Resistance Rigid Perfectly Plastic Hinge (LRPH). In particular, LRPH is a steel device of finite length realizing a moment connection between beam elements of a steel frame; it is designed in order to possess two main and independent requirements: its bending moment resistance must be suitably lower than the one of the connected beam element and its overall bending stiffness must be equal to that of the connected beam element characterized by the same length. In order to make the proposed device reliable, LRPH must be capable of realizing a full plastic hinge for the assigned be…

Influence of formalin fixation on the biomechanical properties of human diaphyseal bone.

2010

Owing to the lack of fresh human bones, formalin-fixed specimens are frequently used in biomechanical testing. However, formalin fixation is assumed to affect the biomechanical properties of bone. The aim of this study was to compare axial and torsional stiffness and bone mineral density in fresh and embalmed human bones. The subtrochanteric regions of 12 pairs of fresh human femora were randomised into two groups for paired comparison. After bone mineral density measurement, one group was preserved in 4% formalin. After 6 weeks, bone mineral density was remeasured and each specimen underwent axial and torsional loading. The formalin group showed significant higher stiffness values for tors…

Sind winkelstabile Plattensysteme mit elastischen Eigenschaften für die Stabilisierung der Oberarmkopffraktur vorteilhaft? / Eine in-vitro biomechani…

2004

AbstractWinkelstabile Platten werden mit zunehmender Häufigkeit zur Stabilisierung von Oberarmkopfbrüchen verwendet. Rigide Implantate führen bei osteoporotischen Knochenverhältnissen u. U. aber häufiger zum Versagen. Um den Effekt der Implantatelastizität zu beurteilen wurden in einer in-vitro Studie die biomechanischen Eigenschaften eines rigiden und eines elastischen winkelstabilen Plattensystems vergleichend analysiert. An 8 Humeruspaaren wurde eine instabile subkapitale Fraktur simuliert. Die Proben wurden axial- und torsions-belastet. Analysiert wurden die Steifigkeit, das Setzverhalten unter Dauerlast und die Versagensbelastung.Das elastische Plattensystem kennzeichnete sich durch ei…

Retrograde nailing versus locking plate osteosynthesis of proximal humeral fractures: a biomechanical study

2011

Background In locking plate osteosynthesis of proximal humeral fractures, secondary varus malalignment is a specific complication. Retron nails (Tantum AG, Neumunster, Germany), among others, have been designed to improve medial support of the calcar humeri. The aim of our biomechanical study was to examine whether Retron nails provide increased stiffness for axial loads and adequate stiffness for torsional loads when compared with Philos plates (Synthes AG, Umkirch, Germany). Materials and methods Twenty-two fresh-frozen paired humeri were collected. After potting the specimens, intact bones were exposed to sinusoidal axial (10-120 N) and torsional (±2.5 Nm) loading for 8 cycles to calcula…

Repeatability of a computer-controlled posterior to anterior vertebral stiffness in subjects with thoracic spine pain

2015

Fatigue of Mooring Chains Connected to Offshore Floating Structures Considering Out of Plane Bending Effects

2019

Abstract Reliability against fatigue fracture is an issue of major concern in the design of offshore mooring systems with chain segments. The present paper describes the investigation of the effect of OPB (out of plane bending) and IPB (in plane bending) loading modes on the fatigue performance of chain links in critical positions. The hang-off design at the floater is based on long rods with bearings at the connection points to the floating structure. The purpose of the paper is to shed some light on possible design improvements on the connection design when using the available design guidelines for calculation of combined Tension-Bending fatigue in the mooring line. A challenge when using…