Challenges in Procurement, Design and Construction of the Erasmusrand Pedestrian Bridge

<p>The new Erasmusrand Pedestrian bridge replaced the previously severely damaged pedestrian bridge spanning across the National Route N1 highway in Pretoria, South Africa, for the South African National Roads Agency SOC Ltd (SANRAL). The structure consists of a steel arch supporting a composite steel/concrete deck with inclined square hollow steel struts. The bridge spans 73m across a 10-lane dual carriageway freeway providing access to a local school from the suburbs. Several challenges were presented in the project with procurement, design and construction.</p>

Unified approach for bridge deck design

Current Canadian Highway Bridge Design Code includes design provisions to establish live load demands in (i) reinforced concrete decks over longitudinal girders, (ii) orthotropic deck over longitudinal girders, and (iii) orthotropic deck over transverse beams. However, it only provides an equation for factored applied moment on concrete deck under single point load. Similar equations for orthotropic decks are as yet unavailable. As such, parametric study was conducted to lead to new empirical expressions for moment in bridge decks subjected to truck wheel loading considering each of the three cases of orthotropy: (i) relatively torsionally stiff, flexurally soft decks; (ii) relatively uniformly thick decks; and (iii) relatively torsionally soft, flexurally stiff decks. Using the proposed formulations, bridge deck design can be treated in a unified way across different deck types, accounting for longitudinal-transverse flexural rigidity of decks. Application of these methods can significantly simplify the analysis of decks and allow bridge engineers to make comparisons across different deck design alternatives.

Unified approach for bridge deck design

Current Canadian Highway Bridge Design Code includes design provisions to establish live load demands in (i) reinforced concrete decks over longitudinal girders, (ii) orthotropic deck over longitudinal girders, and (iii) orthotropic deck over transverse beams. However, it only provides an equation for factored applied moment on concrete deck under single point load. Similar equations for orthotropic decks are as yet unavailable. As such, parametric study was conducted to lead to new empirical expressions for moment in bridge decks subjected to truck wheel loading considering each of the three cases of orthotropy: (i) relatively torsionally stiff, flexurally soft decks; (ii) relatively uniformly thick decks; and (iii) relatively torsionally soft, flexurally stiff decks. Using the proposed formulations, bridge deck design can be treated in a unified way across different deck types, accounting for longitudinal-transverse flexural rigidity of decks. Application of these methods can significantly simplify the analysis of decks and allow bridge engineers to make comparisons across different deck design alternatives.

A State-of-the-Art Review on Hybrid GFRP-Concrete Bridge Deck Systems

The state-of-the-art review of hybrid GFRP-concrete systems for bridge decks is presented in this study. Previous research on the experimental work, analytical modeling, and field application on hybrid GFRP-concrete deck systems are presented, along with a variety of deck systems are discussed. Then, seven typical types of connection technology between FRP and concrete are introduced and compared. Besides, the current progress on the performance of shear connections via beam tests, pushout tests, and pullout tests are probed, respectively. Finally, general conclusions are made, identifying the need for future research.

Parametric Study of the Intermediate External Bracing System of Composite Steel Box Girder Bridges

During the pouring of concrete deck, the installation of external bracing between the inner and outer girders may be necessary when the bridge has sharp curve in order to control the deflection and rotation of the girders. However, it is important to minimize the number of external bracing members, as they have expensive cost and they also have opposite effects for the fatigue features of the steel tub girders. The analysis of curved box girder bridges is carried out numerically by the use of finite element method through (ANSYS 19.2) software. The curved box girder with the intermediate external diaphragms was modeled and the analysis was carried out for many parameters like external bracing sections, girders with or without concrete deck, girders with end diaphragms or without them. The study concluded that ANSYS program has a good ability in evaluating the external bracing force comparing with code equations.

Rose Fitzgerald Kennedy bridge over the River Barrow. Design and Construction of a long span extrados bridge

<p>This paper describes the key elements from early planning to completion of a new bridge over the River Barrow which is part of the New Ross bypass in the south of Ireland. The structure has a total length of 887m, with a span arrangement of 36-45-95-230-230-95-70-50-36m. The two central twin spans are the longest of its kind in the world (extrados with a full concrete deck). The bridge carries a dual carriageway with a cable arrangement consisting of a single plane of cables located in the central axis of the deck. The design and construction focused in providing a structure with long term durability, resilience, and a robust approach to design scenarios using the Eurocodes and state of the art analysis techniques, including extreme events such as fire and ship impact<i>.</i></p>