Special Issue 2016

Marcello Arici, Michele Fabio Granata

Abstract:Incrementally launched bridges are very competitive for the construction of continuous prestressed or composite steel decks. During construction the static scheme of these bridges varies continuously, with the advancement of the deck above piers, producing temporary stresses rather different from those occurring in service life. Several of these bridges can be horizontally curved and the deck maybe composed of thin-walled sections: I-girders or boxes. Moreover curved girders are always subjected to twisting moment, associated to bending, even for dead load. In these cases the influence of non-uniform torsion becomes sizable with respect to the Saint Venant torsion, modifying the state of tangential stresses in the cross section and introducing axial stresses due to the prevented warping. In this paper an analysis method for the evaluation of non-uniform torsion effects in curved prestressed concrete girder bridges, built by the incremental launching method, is proposed. The analysis is performed by the Hamiltonian Structural Analysis method, which leads to derive directly the solution via transfer matrices. In this paper the generalized technique of Reduced Transfer Matrices is applied to the launching stages of continuous girder bridges. The comparison between two different methodologies of construction is performed. In a first case the bridge is launched with its whole concrete box section, while in a second case only a U-shape section without the upper slab is launched, in order to reduce the deck weight and the launching equipments. Results are shown on a case-study through envelope diagrams of internal forces and stresses for the entire sequence of launching. The influence of secondary torsion is addressed and the consequent variation of the state of stress is underlined.

International Journal of Bridge Engineering, Special Issue 2016: pp. 1-21

Alessandro Baratta, Ileana Corbi, Ottavia Corbi, Francesca Tropeano

Abstract:In the paper the performance of ancient masonry vaulted bridges is investigated through the analysis of a study case which is referred to, in the region Campania, that is the Devil’s bridge on Sele river in Capaccio. The proposed methodological approach is aimed at emphasizing a number of features, including the main vault/fill interaction, the overall cooperation of the structural and non-structural components.

International Journal of Bridge Engineering, Special Issue 2016: pp. 23-37

Spyridoula M. Papathanasiou, Panos Tsopelas, Evgenia Prapa, Alper Ucak

Abstract:The impact of the Soil-Structure Interaction (SSI) on seismic isolated bridges is investigated. Two stick models of two seismically isolated bridges and equivalent models of the functions of soil-pile group system are considered. The frequency-dependent impedance models consist of frequency-independent springs and dashpots as well as "gyromasses", which are elements proposed recently in the literature. Each "gyromass" plays the role of an ordinary mass, with the advantage of not altering the dynamics of the system since does not add additional inertial forces into the system. Appropriate assemblies of springs, dashpots, and "gyromasses" can match in the frequency domain even the most frequency-sensitive impedance functions providing an advantage over simple Voigt models (spring-dashpot in parallel) used frequently for SSI analyses. The models are suitable for use in time domain and are utilized in this study for the nonlinear time history analyses of the bridges, subjected to 2 sets, near fault (NF) and the far field (FF), of 20 motions. The paper considers factors which influence the SSI effects on a seismically isolated bridge, number and geometry of piles, spacing of piles, soil characteristics, flexibility of superstructure, and examines how the SSI modeling, Gyromodels vs Voigt models, influence the response parameters of such structures. The results are presented in terms of displacements and forces of the structural system and some general conclusions are drawn over the appropriate modeling systems of each case of study

International Journal of Bridge Engineering, Special Issue 2016: pp. 39-70

Antonino Recupero, Giuseppe Longo, Michele Fabio Granata

Abstract:Cable structures are often used as final or partial intermediate structures in construction stages of bridges like arch bridges or cable-stayed ones. These bridges are built often by cantilevering, i.e. with subsequent cantilever partial structures, which are cable-stayed too; hence, every construction stage is a cable structure to be analyzed. The methodology of structural analysis of these construction stages as well as the modeling of the structure for the determination of initial cable force are fundamental steps for establishing the actual state of stress and deformation. In the paper, a general methodology of analysis for construction sequences of cable-stayed structures is presented, which can be used both for the design of cable-stayed bridges and arch bridges. The proposed methodology is based on the simple analysis of multiple partial elastic schemes, which follow the actual construction sequence. The aim is that of obtaining a convenient final geometry through the control of deformations from the first stage to the last one, coincident with the service life configuration. Geometry and internal forces are contemporary checked, as well as cable forces are determined without the need of too many stressing adjustments. Results of analyses, performed for different case-studies, are reported, summarized and commented, in order to show the reliability and the wide range of applicability of the proposed methodology of analysis.

International Journal of Bridge Engineering, Special Issue 2016: pp. 71-96

Domenico Bruno, Fabrizio Greco, Paolo Lonetti

Abstract:An analysis on the effects produced by failure mechanisms in the cable system is proposed to investigate the behavior of cable-stayed bridges. In particular, the present paper aims to verify the influence on the bridge behavior of accidental breakages produced in the cable system elements also in light of existing design guidelines available from the literature. In the present paper, the numerical model is based on a refined description of the bridge, which involves bridge constituents and external loads. In particular, a geometric nonlinear formulation in which the effects of local vibrations in the stays and large displacements in girder and pylons are taken into account. Moreover, damage effects are simulated by using an accurate description of the release effects produced by the cable-breakage processes. The results denote that several parameters associated with cable-breakage processes, such as the breakage duration, time-transient curve and external load description, are found to influence the dynamic performance of the bridge.

International Journal of Bridge Engineering, Special Issue 2016: pp. 97-115

Ioannis G. Raftoyiannis, George T. Michaltsos

Abstract:The present work studies the behavior of an arch bridge under the action of moving loads and proposes a mathematical model for the solution of the problem. The arch bridge under study may have a discontinuous deck or a continuous one, while the columns supporting the deck to the arch are considered as non-extensible. A 2-DOF model is considered for the solution of the bridge while the theoretical formulation is based on a continuum approach, which has been used in the literature to analyze such bridge types.

International Journal of Bridge Engineering, Special Issue 2016: pp. 117-134

Sarira Motaref, M. Saiid Saiidi, David Sanders, Amir Mirmiran

Abstract:An experimental and analytical study was conducted on the seismic performance of a 0.3-scale two-column bent incorporating two precast columns with advanced materials, a precast footing, and a precast cap beam. The objective was to determine if the connection details and construction methods used in this study are appropriate for accelerated bridge construction (ABC) in high seismic zones and if using advanced materials can reduce the earthquake damage compared to conventional reinforced concrete columns. One column was built using conventional reinforced concrete, but incorporated ECC (engineered cementitious composite) in the plastic hinge zone instead of concrete. The other column consisted of a glass fiber reinforced polymer tube filled with concrete. Two pockets were formed in the footing to allow for insertion of precast columns. The column embedment length was designed to transfer the full plastic moment of the column to the footing. The column-pier cap connection was a telescopic steel pipe pin adapted for ABC. The pier model was subjected to the Sylmar earthquake record simulated on a shake table with increasing amplitudes until failure. Test results showed that the seismic performance of both columns was satisfactory and that the embedment length was sufficient to develop the plastic moment in both columns. A comprehensive analytical model of the pier was developed using OpenSEES and acceptable correlation was obtained between the measured and calculated data. Parametric studies were conducted to determine the effect of variables that were not included in the experimental studies.

International Journal of Bridge Engineering, Special Issue 2016: pp. 135-162

Roberto Cairo, Giovanni Dente, Stefano Dodaro

Abstract:The dynamic response of structures to earthquake loading depends mainly on: the characteristics of the incident seismic waves; local site conditions, such as topographic irregularities and heterogeneity of the soils; the presence of stiff and heavy embedded foundations; the deformability of the soil supporting the structures. These phenomena can be relevant for bridges that usually have deep foundations and extent over considerable distances. In this paper the dynamic response of a bridge pier subjected to polarized shear waves is investigated. Different wave patterns are considered and the corresponding free-field ground motion is calculated with reference to a linear elastic halfspace. The pier is founded on a rigid caisson and soil-structure interaction is solved using the Winkler type model developed by Gerolymos and Gazetas.

International Journal of Bridge Engineering, Special Issue 2016: pp. 163-184

Marcello Cammarata, Giovanni Minafò, Nunzio Scibilia

Abstract:The paper describes some problems with the design of road bridges using welding sinusoidal corrugated steel web beams. The deck is made of two main steel girders, transversally connected by steel beams and by a reinforced concrete slab, prestressed and not. The design is carried out for a category I bridge that is 13.70 m wide and 52.00 m length. It is examined the behavior of steel girders, loaded of its own weight and of the weight of the r.c. plate, as the independent beam, as well the beams connected by transversal elements. The effects due to the shrinkage and the permanent loads are considered by taking into account the viscosity. The solutions analyzed have been compared with similar structures with stiffened web. The analyses performed are validated with reference to the Italian and to the European Codes.

International Journal of Bridge Engineering, Special Issue 2016: pp. 185-196

Antonios Kladis, Fani Gelagoti, Marianna Loli, George Gazetas

Abstract:Surface fault ruptures may inflict serious damage to bridges built on top or near them, as amply demonstrated in three notorious earthquakes, Kocaeli, Chi–Chi, and Wenchuan, among others. Successes have also been observed, providing the impetus for research into the design against tectonic deformation. To circumvent the formidable 3D analysis, previous research efforts on the subject had decomposed the problem, with the free-field solution of the fault propagation as a first step, followed by the analysis of the bridge system subjected to the calculated deformations of the free-field step. This paper attempts a robust investigation of the entire bridge system (soil, foundation, pier, deck) with the intention to elucidate the significance (or not) of the kinematic constraints imposed by the superstructure on the overall bridge response. To this end, a typical highway bridge founded on shallow footings is subjected to a dip–slip “normal” and “thrust” faulting. A series of physical model-scale experiments are about to be conducted in a split-box apparatus, capable of imposing normal and thrust type base offsets. In this study (before the model tests are conducted) a numerical prediction of the forthcoming experimental results is attempted, evaluating simultaneously the decoupled methodology of Anastasopoulos et al. 2008. 2D finite element analyses accounting for soil strain-softening are conducted. The position of the footing relative to the surface fault rupture and the imposed kinematic constraints on the abutments are also parametrically investigated, assessing the developing various mechanisms and the corresponding distress of the bridge. This paper is the first of a two-paper sequence presenting a genuine numerical prediction of a forthcoming physical experiment at a 1:15 scale.

International Journal of Bridge Engineering, Special Issue 2016: pp. 197-219

Giuseppe Vairo

Abstract:In this paper, a critical review on modeling of wind loads on longspan bridges is traced. Starting from the theoretical background associated to the classical thin airfoil model and from a generalized quasi-steady wind-loading description, a unified consistent approach is proposed. The general frameworks of both frequency-domain and time-domain loading models are exploited, generalizing available approaches and eliminating commonly diffused inconsistencies, in order to preserve the main formal scheme of thin-airfoil-based classical results. The strong duality between time-domain and frequency-domain descriptions is clearly highlighted for both motion-related (aerolastic) and buffeting loads. Finally, in the same unified context, a brief overview of the main open topics and of possible effective strategies to account for some unconventional effects (e.g., related to flow three-dimensionality and nonlinear aerodynamics) is drawn.

International Journal of Bridge Engineering, Special Issue 2016: pp. 221-259