BRIDGE DESIGN PRACTICE ● FEBRUARY 2015

Zenodo (CERN European Organization for Nuclear Research), 2022

Increasing urban population, traffic flow and restricted available width to spread horizontally in cities,prestressed concrete wide-deck box girders have been increasingly usedespecially spine and wing arrangement either withbox girder with transverse ribs or box girder with struts, for constructing new bridges and flyovers. A ribbed cantilever slab or cantileverwith supportingstruts can increase the cantilever length and transverse stiffness while reducing the dead weight of the deck. Present trend is to provide only a single median pier to cover the wide deck, so that both surface level space underneath elevated corridor as well as at the elevated level space can be fully utilized for the traffic movement.Bridge aesthetics are also very important as bridges are located in cities, prime locations, tourist's spots. A literature study revealed that the prestressed concrete box girders with transverse ribs are already used in to meet the requirements of wide bridge decks of single-cell concrete box girders. However, little research has been conducted. The objective of this study is to understand the behavior of different types of wide deck bridge superstructure systems and their suitability with respect to various aspects such as analysis and design along with their construction, site constraints, handling, segment erecting schemes for choosing best suitable option for a particular project.

Computer Aided Bridge Design, 2020

By using AASHTO-LRFD Standard, the design of deck slab and Cantilever Slab are done by calculating bending moments, shear forces, bending resistance in transverse direction, bending resistance in longitudinal direction, checking flexural cracking. The Design of PSC I-Girders is done for Bending moments and Shear forces by Dead Load, Super Imposed Dead Load (SIDL) and Live Loads (LL). The Shrinkage strain, Creep Strain and effect of Temperature rise and fall are also determined. The design is complete for Pre-stressing cables, End anchorages, un-tensioned reinforcements, End cross girder, Shear connectors. The values in 'Red Color' are Design Input Data by the User. Note: For any query write to [email protected] 2.0 General The span arrangement and configuration should be closely studied first in respect of the site location of the bridge. A bridge crossing over a navigable waterway is very much dictated by the horizontal and vertical clearance required. It is also important to know the soil condition and landscapes (e.g., over water, land, valley, or mountainous area). For segmental concrete bridges uniformity of the span lengths is critical in order to maximize the benefit of pre-casting the segments. The more uniform the span distribution, the more economical the bridge. It is also preferable to have an uneven number of spans from the architectural point of view. A range of 20 to 50 metres for PSC I-Girder and 30 to 60 metres for incremental launched box girders bridges are recommended. It is not recommended to place many piers with short span lengths. Therefore, the number of piers should be reduced and the span length increased. The shape and size of the piers are also important. For shorter span length, the lateral pier dimensions should be slender in order to reduce the wall view effect from an oblique view. For shallow valley, it is important to consider the L/H ratio of the opening between two piers, where L is the span length and H is the pier height. It is preferable to have an L/H ratio equal to or greater than 1.5. The end spans should be less than the typical span length (60% to 80% of typical span length) in order to achieve an efficient design.

Task Order DTFH61-02-T-63032 4-1 Design Step 4 DECK SLAB DESIGN Design Step 4.1 In addition to designing the deck for dead and live loads at the strength limit state, the AASHTO-LRFD specifications require checking the deck for vehicular collision with the railing system at the extreme event limit state. The resistance factor at the extreme event limit state is taken as 1.0. This signifies that, at this level of loading, damage to the structural components is allowed and the goal is to prevent the collapse of any structural components. The AASHTO-LRFD Specifications include two methods of deck design. The first method is called the approximate method of deck design (S4.6.2.1) and is typically referred to as the equivalent strip method. The second is called the Empirical Design Method (S9.7.2). The equivalent strip method is based on the following: • A transverse strip of the deck is assumed to support the truck axle loads. • The strip is assumed to be supported on rigid supports at the center of the girders. The width of the strip for different load effects is determined using the equations in S4.6.2.1. • The truck axle loads are moved laterally to produce the moment envelopes. Multiple presence factors and the dynamic load allowance are included. The total moment is divided by the strip distribution width to determine the live load per unit width. • The loads transmitted to the bridge deck during vehicular collision with the railing system are determined. • Design factored moments are then determined using the appropriate load factors for different limit states. • The reinforcement is designed to resist the applied loads using conventional principles of reinforced concrete design. • Shear and fatigue of the reinforcement need not be investigated. The Empirical Design Method is based on laboratory testing of deck slabs. This testing indicates that the loads on the deck are transmitted to the supporting components mainly through arching action in the deck, not through shears and moments as assumed by traditional design. Certain limitations on the geometry of the deck are listed in S9.7.2. Once these limitations are satisfied, the specifications give reinforcement ratios for both the longitudinal and transverse reinforcement for both layers of deck reinforcement. No other design calculations are required for the interior portions of the deck. The overhang region is then designed for vehicular collision with the railing system and for

1997

For more than 25 years, concretes with compressive strengths in excess of 41 megapascals (MPa) (6,000 pounds per square inch (psi)) have been used in the construction of columns of highrise buildings. While the availability of high-strength concretes was limited initially to a few geographic locations, opportunities to use these concretes at more locations across the United States have arisen. Although the technology to produce higher-strength concretes has developed primarily within the ready-mix concrete industry for use in buildings, the same technology can be applied in the use of concretes for bridge girders and bridge decks. The durability of concrete bridge decks has been a concern for many years, and numerous strategies to improve the performance of bridge decks have been undertaken. Many of the factors that enable a durable concrete to be produced also result in a high-strength concrete. Consequently, if a concrete for a bridge deck is designed to be durable, it will probably also have a high compressive strength. This report contains an evaluation of the effect of high-performance concrete on the cost and structural performance of bridges constructed with high-performance concrete bridge decks and high-strength concrete girders. Several areas with the potential for improved structural performance through the use of high-performance concretes are investigated. This report should also assist designers and owners in recognizing that the use of highperformance concrete in bridges has advantages beyond those of improving durability.

By using British Standard Eurocode 2, the design of deck slab and Cantilever Slab are done by calculating bending moments, shear forces, bending resistance in transverse direction, bending resistance in longitudinal direction, checking flexural cracking. The Design of PSC I-Girders is done for Bending moments and Shear forces by Dead Load, Super Imposed Dead Load (SIDL) and Live Loads (LL). The Shrinkage strain, Creep Strain and effect of Temperature rise and fall are also determined. The design is complete for Pre-stressing cables, End anchorages, un-tensioned reinforcements, End cross girder, Shear connectors. 3.0 General This chapter emphasizes on introducing the typical process of designing deck-girder superstructure of pre-stressed concrete bridge, along with the consideration that a design engineer needs to take through each phases of the design process. A wide range of contents with respect to bridge design process are covered in this chapter. Upon the completion of structural analysis, the bridge will be designed in detail. The step by step procedure of determining the concrete section dimensions, pre-stressing tendon profile, reinforcing bar layout and material properties are specified in this chapter. The initial girder size is usually selected based on past experience. Some engineering departments have a design aid in the form of a table that determines the most likely girder size for each combination of span length and girder spacing. Such tables are developed by using the specific live loading of the relevant Standard Specifications are expected to be applicable to the bridges designed using the standard Specifications. The strand pattern and number of strands was initially determined based on past experience and subsequently refined using a computer design program. This design was refined using trial and error until a pattern produced stresses, at transfer and under service loads that fell within the permissible stress limits and produced load resistances greater than the applied loads under the strength limit states.

2006

Spatial structure is a truss-like, lightweight and rigid structure with a regular geometric form. Usually from these structures is used in covering of long-span roofs. But these structures due to the lightness, ease and expedite of implementation are a suitable replacement for bridge deck. However steel and concrete is commonly used to build bridge deck, but heavy weight of steel and concrete decks and impossibility of making them as long-span bridge deck is caused engineers to thinks about new material that besides lightness and ease of implementation, provide an acceptable resistance against applied loads including both dead load and dynamic load caused by the passage of motor vehicles. Therefore, the purpose of this paper is design and analysis bridge deck that’s made of double-layer spatial frames compared with steel and concrete deck. Then allowable deflections due to dead and live loads, weight of bridge in any model and also economic and environmental aspects of this idea is checked. As a result, it can be said that the use of spatial structures in bridge deck is lead to build bridge with long spans, reducing the material and consequently reducing the structural weight and economic savings. For geometric shape of the spatial structure bridge is used of Formian 2.0 software and for analysis of bridges is used of SAP2000 with finite element method (FEM).