BOX BRIDGE GIRDER (BBG)

About BOX BRIDGE GIRDER (BBG)

Box bridge girders are prefabricated using the revolutionary composite material of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) and high- carbon-high-tensile steel fibers. It is an excellent solution for bridge engineers looking for a cost effective, fast construction, light-weight and high-durability option for bridge span range of 80 to 100 meters

Features

The UHPFRC used to manufacture the DURA BBG has a minimum characteristic compressive strength of C140/155 MPa, tensile strength of T7/8MPa and flexural strength of F10/20 MPa.
The DURA BBG eliminates the use of conventional steel reinforcing bars and stirrups, except at regions where bursting reinforcements are needed and jointing details are required for composite construction. All steel fibers used are made from high carbon steel wires with the minimum tensile strength of 2500MPa. Also, the steel wires are manufactured in compliance with the EN14889 or ASTM A820 standards.
The DURA BBGs are assembled using-tensioning methods on several segmental pieces of the same kind. For example, the 100m span bridge (refer to page 26) generally composed of 40 segments (i.e 36 standard identical 2.5m long anchorage segments weighing 20 tonnes). The second-to the end segments weigh 18 tonnes. With 30 tonnes of pre-stressing cable, 10 tonnes of grout, 52 tonnes for the wearing surface and 30 tonnes for railings and ancillary fixtures, the total weight of the bridge is about 780 tonnes. The only conventional reinforcement for transfer of longitudinal shears at the connection of the top flanges and the UHPFRC deck slab is cast in a second pour.

Advantages

REPLACEMENT OF CONVENTIONAL CONSTRUCTIONS
DURA BBG is used to replace conventional segmental box girder (SBG) as it is half it’s weight. Steel composite deck construction is also replaced with DURA BBG which is about 10 to 20% heavier
IMMEDIATE SAVINGS
A minimum of 20-30% of immediate savings can be attained for the substructure and foundation cost due to it is lighter superstructure, especially on difficult ground condition
EASY HANDLING
Due to it’s ultra-light weight compared to conventional beams, it is easy to handle and fast in construction
DURABLE
At least 5 times more durable as it uses UHPFRC which consist of discrete high strength steel fibers to stitch cracks, and is designed based on uncracked approach at SLS, increasing the infrastructure’s life span
LESS CORROSION & IMPERMEABLE
DURA girders can be designed and made in much slenderer and effecient sections, to prevent corrosion of steel reinforcement. No waterproofing needed as DURA is highly impermeable material
LOWER INDIRECT COST
Shallower bridge beams are needed. The reduction of girder depth can lead to indirect cost saving resulting from minimal cut and fill of the embankment or approach bridge levels