Suspension bridge

A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridges, which lack vertical suspenders, have a long history in many mountainous parts of the world. Besides the bridge type most commonly called suspension bridges, covered in this article, there are other types of suspension bridges. The type covered here has cables suspended between towers, with vertical suspender cables that transfer the live and dead loads of the deck below, upon which traffic crosses. This arrangement allows the deck to be level or to arc upward for additional clearance. Like other suspension bridge types, this type often is constructed without the use of falsework. The suspension cables must be anchored at each end of the bridge, since any load applied to the bridge is transformed into tension in these main cables. The main cables continue beyond th

Probabilistic Prediction and Forecast of Daily Suspended Sediment Concentration on the Upper Yangtze River

José Pedro Gamito de Saldanha Calado Matos, Mário Jorge Rodrigues Pereira Da Franca

Sediment transport in suspension can represent more than 90% of a river's total annual flux of sediment. In the case of the Yangtze River, more than 99% of the sediment supplied to the sea is suspended load. Suspended sediment is thus an important component of the total sediment load, with implications for channel dynamics, landscape evolution, ecology, and human-related activities. For hydrological management of large basins such as the Yangtze River, knowledge of the processes governing suspended sediment concentration (SSC) is essential. An analysis of the temporal variation of SSC for the Upper Yangtze basin (defined at Pingshan station) is presented here. For this purpose, a database of 50years of concurrent discharge and SSC measurements, made by the Yangtze River Commission, is used. The analysis is made using a novel probabilistic data-driven technique, the Generalized Pareto Uncertainty (GPU). This technique allows for the testing of several strategies of prediction and forecast applied to a time series of SSC and streamflow. Changing between local or seasonal variables to feed these strategies, we inferred that although the main driver of the SSC transport is flow (as reported by previous authors), sediment storage is also a major control. Furthermore, the maximum necessary time lag for forecasts made with the data is on the order of one week, which provides one indication of the time scale of the local processes of SSC transport in the Upper Yangtze. In this paper, limitations and data requirements of the GPU methodology are also discussed. Plain Language Summary In this manuscript we use a probabilistic technique to study what controls the dynamics of the sediments in suspension in Upper Yangtze River. For that, a database of 50 years of measurements of streamflow and sediments in suspension collected at Pingshan station by the Yangtze River Commission was analyzed with a new technique. Sediments in suspension represent the major portion of total sediment load in most river systems, and the Yangtze River is no exception. Fine sediment dynamics is an important component of many physical, chemical, and biological processes in rivers.

AMER GEOPHYSICAL UNION2018

Through-thickness performance of adhesive connections between FRP bridge decks and steel main girders

Martin Schollmayer

FRP bridge decks offer several advantages compared with conventional concrete bridge decks, particularly their much lower weight, but also their resistance against corrosion as well as easier installation and maintenance. The poorly conceived methods available for connecting FRP bridge decks with their supporting structures – normally steel girders – nonetheless constitute a disadvantage. Connections involving studs or bolts are not appropriate in this case, since FRP is a very brittle material that offers no ductile properties. Bolted connections usually result in much higher stress concentrations, while adhesive bonding is a more material-adapted connection method since larger surfaces can be linked together, thus ensuring reduced stresses. The bridge system investigated in this thesis consists of a pultruded FRP bridge deck bonded to steel main girders, the bridge's main structural components, which have to transmit the dead and traffic loads to the supports, whereas the bridge deck is spanned in the transverse direction perpendicular to the steel girders. Uplift forces caused by the load-bearing behavior of the bridge deck transverse to the bridge axis lead to through-thickness tensile stresses in the adhesive joint. The main objective of this thesis is the description of the structural behavior in the transverse direction. This includes analysis of the stresses in the adhesive connection as well as determination of the strength of the joints. Analytical and experimental investigations were carried out. It was shown, that the tensile stress distribution in the adhesive joint is non-uniform with high stress concentrations below the FRP deck webs of the cellular deck and above the steel girder web. Alternately inclined deck webs thereby induce significantly higher stresses below the vertical webs. A method for the calculation of the stress state in the adhesive layer is proposed which is validated by numerical and experimental results. The material strength of the connection in terms of a combination of tensile through-thickness and shear stresses is established. The total safety factor of the joint was higher than the safety factor of the FRP deck for bending between the main girders. A possible failure process would not start in the adhesive connection between bridge deck and steel girder which eventually could lead to additional failure of other structural members. The system is redundant. Fatigue loading up to 10 million cycles showed no stiffness degradation. The results of this thesis prove the existence of a good load-bearing behavior under static and fatigue loads of adhesively-bonded joints between pultruded FRP bridge decks and structural steel girders, where the adhesive connection is loaded with uplift forces and moments acting in the bridge deck, in addition to the shear in the connection layer due to composite action. The basis for a design method for adhesively-bonded connections between pultruded FRP bridge decks and steel girders is provided.

EPFL2009

Through-thickness performance of adhesive connections between FRP bridge decks and steel main girders

Martin Schollmayer

EPFL2009

Probabilistic Prediction and Forecast of Daily Suspended Sediment Concentration on the Upper Yangtze River

José Pedro Gamito de Saldanha Calado Matos, Mário Jorge Rodrigues Pereira Da Franca

AMER GEOPHYSICAL UNION2018

Fatigue Tests and Analysis of Reinforced Concrete Bridge Deck Models -

Probabilistic Prediction and Forecast of Daily Suspended Sediment Concentration on the Upper Yangtze River

Through-thickness performance of adhesive connections between FRP bridge decks and steel main girders

Through-thickness performance of adhesive connections between FRP bridge decks and steel main girders

Fatigue Tests and Analysis of Reinforced Concrete Bridge Deck Models -

Probabilistic Prediction and Forecast of Daily Suspended Sediment Concentration on the Upper Yangtze River