Search results for " loading"
showing 10 items of 157 documents
Discrete variable design of frames subjected to seismic actions accounting for element slenderness
2015
An optimal design problem formulation of elastic plastic frames under different combinations of fixed and seismic loads is presented. The optimal structure must behave elastically for the fixed loads, shakedown for serviceability conditions and prevent instantaneous collapse for fixed and high seismic loads. P-Delta effects and element buckling are considered. An appropriate modal technique is utilized. The design variables can have components in a continuous field or, alternatively, in chosen discrete sets or, yet, both kind of variables can be present. The design problem is formulated on the ground of a statical approach. The applications are related to steel frames.
Minimum volume design of structures with constraints on ductility and stability
2014
Abstract A minimum volume design problem of elastic perfectly plastic frame structures subjected to different combinations of fixed and seismic loads is presented, in which the design variables are considered as appertaining alternatively to a continuous assigned range as well as to appropriate discrete sets. The structure is designed so as to behave elastically for the applied fixed loads, to shakedown in presence of serviceability seismic conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and high seismic loadings. In order to avoid further undesired collapse modes, the P-Delta effects are considered and the structure is also constrained to prev…
Seismic shakedown design of frames based on a probabilistic approach
2014
The present study concerns the optimal design of elastic perfectly plastic structures subjected to a combination of fixed and seismic loads. In particular, plane frames are considered and suitable measures of the beam element cross sections are chosen as design variables. The optimal design is required to behave in a purely elastic manner when subjected just to the fixed load and to have the capability to eventually shakedown when simultaneously subjected to fixed and seismic loads. Due to the natural uncertainness related to the definition of the seismic load history, a new probabilistic approach is proposed, consisting into two subsequent search steps. At first a suitably chosen large num…
Preload loss of abutment screws after dynamic fatigue in single implant-supported restorations. A systematic review
2017
Background To carry out a systematic literature review of the causes of preload loss of the abutment screws, of internal and external connection implants, tightened to different torque values and subjected to cyclic loading. Material and methods A systematic search was conducted in PubMed, EMBASE, and Cochrane Library databases with reference to in vitro studies in which internal and external connection implants were subjected to cyclic loads to determine the degree of loosening of the abutment screws after loading. Results The reviewed studies tested distinct implant connections (mostly externally hexed, and morse taper) subjected to diverse cycles (from 16667 to 1 million), with loads ran…
Immediate Loading in Atrophic Jaws: Zygomatic Implants
2019
The zygomatic fixture is an extended length (35–55 mm) titanium implant, placed into the zygomatic and maxillary alveolar bone. It was designed for situations where atrophy of the posterior maxilla complicates or prevents the placing of conventional implants. The use of zygomatic implants avoids the need for bone grafting, shortens treatment times, and reduces morbidity. They have also been used in patients with maxillectomies resulting from tumors or diseases associated with atrophic conditions of the maxilla.
Diagnosis and Planning in Immediate Loading: Prosthetic Diagnosis
2019
Immediate loading provides functional and esthetic advantages, improving the quality of life of the patient during the osseointegration period. But, clinicians have to know that the three key parameters that should be evaluated for prosthetic planning of the totally edentulous patient are prosthetic space, lip support, and smile line. This is a crucial part of the planning because the prosthetic space, lip support, and smile line determine the type of prosthetic restoration.
Immediate Loading in All-on-Four
2019
Severe bone atrophy of the upper maxilla (Cawood and Howell class V and VI) is associated with certain problems such as reduced perioral tissue support, the impossibility of wearing complete dentures, chewing and speech alterations, and difficulties in placing dental implants due to the limited amount of available bone.
Stochastic ship roll motion via path integral method
2010
ABSTRACTThe response of ship roll oscillation under random ice impulsive loads modeled by Poisson arrival process is very important in studying the safety of ships navigation in cold regions. Under both external and parametric random excitations the evolution of the probability density function of roll motion is evaluated using the path integral (PI) approach. The PI method relies on the Chapman-Kolmogorov equation, which governs the response transition probability density functions at two close intervals of time. Once the response probability density function at an early close time is specified, its value at later close time can be evaluated. The PI method is first demonstrated via simple …
Die Wirkung von Oxytocin auf die renale Ausscheidung und auf die Ausbildung eines Stauungs�dems bei der Ratte
1960
1. An experimental congestion edema was produced in rats by tying of both jugular veins. During 22 hours after the operation the animals were loaded three times with 5 ml./100 g body weight 0,9% saline per os. Each animal received 1000 mU/kg. Syntocinon s.c. one half hour before each fluid loading.
Experimental investigations of the soil–concrete interface: physical mechanisms, cyclic mobilization, and behaviour at different temperatures
2016
Behaviour of the pile–soil interface is important to correctly predict the response of floating piles in terms of displacement and lateral friction. Regarding energy piles, which couple the structural roles of deep foundations with the principle of shallow geothermal energy, the response of pile–soil interfaces is influenced by seasonal and daily cyclic thermal variations. Accordingly, the goal of this paper is to experimentally investigate the response of the pile–soil interface at different temperatures. This experimental campaign aims to analyse (i) the cyclic mobilization of the shear strength of the soil–pile interface that is induced by thermal deformation of the pile and (ii) the di…