Search results for "Ridge"

A parametric study of curved incrementally launched bridges

2013

Abstract The structural behaviour of incrementally launched bridges in the construction stages depends on different parameters involving deck, nose, supports and guide devices, because static schemes vary continuously with the advance of the deck above the piers. For this reason temporary stresses in the deck, during launching, are rather different from those occurring in service life. Horizontally curved launched bridges also present the effects of torsion induced by geometric curvature. A parametric study is presented in order to analyse the influence of design parameters on the construction of these bridges. Analyses were carried out by extending to curved beams a procedure based on the …

Experimental Investigation for Degradation Analysis of an RC Italian Viaduct and Retrofitting Design

2020

AbstractThe degradation state of RC bridge structures is one of the most important and difficult aspects to be interpreted. For these structures, structural analysis using FEM requires a reliable d...

Corrections to “Multipactor Susceptibility Charts for Ridge and Multi-Ridge Waveguides” [Dec 12 3601-3607]

2014

The authors have detected an error in Section IV-A in the above paper (ibid., vol. 59, no. 12, pp. 3601-3607, Dec. 2012). The analyzed rectangular waveguide in the actual version of the article is the WR137, instead of the WR90. As a consequence, the corrections presented here have to be implemented.

Adjustable prestressing for construction stages of incrementally launched bridges

2014

Incrementally launched bridges, which are generally built with the static scheme of a continuous beam on supports, change their scheme several times during launching. In these different configurations, internal forces vary and bending moments of opposite signs occur in the same sections for different positions of deck during advancement. In these bridges, two different kinds of prestressing are necessary: a temporary one during launching and a definitive one in service life. In this study, the possibility of implementing automatic adjustable prestressing for the launching stages is investigated; the launch prestressing is partially supplied by a system which can change the tension value in …

Influence of secondary torsion on curved steel girder bridges with box and I-girder cross-sections

2015

Steel curved girder bridges are largely used today in motorways and railways. They are often composed of thin-walled crosssections, entirely made of steel or with an upper concrete slab. The deck may have I-girders or box cross-sections: in any case curved girders are subjected to twisting moment, associated with bending, even for dead loads. Moreover, in thin-walled sections the influence of non-uniform torsion becomes sizable with respect to Saint Venant torsion, modifying the state of tangential stresses in the section and introducing axial stresses due to warping being prevented. Open sections of I-girder bridges are especially subject to these phenomena and warping can be significant n…

Principles as a Bridge Between Theory and Practice

2020

A Mixed Approach for Determination of Initial Cable Forces in Cable-Stayed Bridges and the Parameters Variability

2015

The determination of initial cable forces in cable-stayed bridges is an important first step in design and analysis of the structure under external loads. Adjustments of stay forces are often required during construction in order to assure the requested behaviour of the bridge in terms of final geometrical configuration and internal force distribution. An accurate assessment of the stay tensioning system allows designers to obtain a good result at the end of construction, by considering the parameters involved as deterministic quantities, assuring the observance of the execution tolerances during works. Actual loads and their variations need instead a stochastic approach which can give usef…

A novel current-based approach for very low variation detection of resistive sensors in wheatstone bridge configuration

2014

Life cycle assessment of large scale timber bridges: A case study from the world’s longest timber bridge design in Norway

2018

Abstract This paper seeks to use life cycle assessment to investigate the comparative environmental impacts of two proposed bridge designs for the new Mjosa Bridge over Lake Mjosa in Norway. The Norwegian Public Roads Administration has designed one timber and one concrete alternative for the 1650 m 4-lane highway bridge. If the timber bridge design is chosen, it will be the longest timber bridge in the world once constructed. The main motivation for building the timber bridge is to utilize local industry and to reduce environmental impacts in road infrastructure. This study aims to determine the expected emissions from both construction designs by using life cycle assessment. Life cycle as…

Serviceability of segmental concrete arch-frame bridges built by cantilevering

2013

The evaluation of the safety degree in service life for a segmental prestressed concrete bridge built by the cantilever method presents different aspects related to strength, deformability, durability and to effects of time-dependent phenomena as creep and shrinkage. The case-study of a prestressed concrete frame bridge with inclined piers is presented, built by cantilevering, with precast segments. By considering the fundamental items of design and construction stages, the implications due to the arch effect in this static scheme are investigated, with respect to an equivalent bridge with a final scheme of continuous girder on vertical piers. The birth of a significant value of axial force…