Project Overview
Spanning more than 1600 ft, a new bridge in Malaysia constructed from precast ultra-high-performance concrete (UHPC) is an impressive feat of engineering, epitomizing the innovation and resilience that precast concrete makes possible. The bridge consists of 15 spans, including 2 abutments and 14 piers, with 1 span crossing the Langat River. While the original propose was for a bridge with a structural steel plate girder system, the team at Dura Technology Sdn Bhd (Dura) worked with the project owner to convert the approach to UHPC U-girders and a cast-in-place concrete deck. Switching the design to a precast concrete solution provided a wide variety of advantages, including lower costs, a faster construction schedule, long-term durability, and more.
A Record-Setting Approach
Contractors built the bridge in a 1000-acre industrial park—one of the largest in the area. Its construction not only solves local traffic congestion but also encourages further development inside the park, which could lead to new businesses and work opportunities for those living in the area.
All of this was made possible thanks to nine record-setting U-girders measuring 344.5 feet in length and weighing 440 tons. Each of the U-girders was manufactured using UHPC and required 220 yd3 of concrete. A special technique was deployed in the precaster’s plant to ensure perfect alignment and match cast segments, with lengths between 21 and 26.2 ft. A long bed was used to cast every other segment along the length. Then, gaps between segments were filled in, achieving the alignment needed. The concrete for each segment also had to be placed continuously, necessitating the use of a large, 15-yd³ mixer.
According to Yen Lei Voo, Dura CEO, the precast UHPC design brought a significant number of advantages to the project. “The cost of the precast solution was 30% less than that of the steel originally planned,” he said. “Additionally, precast concrete helped avoid supply-chain issues while also taking advantage of sourcing locally produced raw materials. We were also able to increase safety on the effort by avoiding the need for skilled workers to weld and bolt structural steel at high elevations.”
UHPC has become increasingly popular as a product of choice for infrastructure projects. The material is recognized by most industry experts as sustainable and durable, leading to shorter construction schedules, extended service life, and minimized maintenance requirements. These attributes, when combined with the general advantages that precast concrete products provide, made the U-girders the perfect solution for the project. “UHPC is expected to be in service for several hundred years with little associated maintenance cost,” Voo said. “When compared to structural steel, the need for frequent painting is also eliminated.”
Despite the difficulties associated with installing massive components and the bridge being on a 44-degree skew, the team was able to erect one precast UHPC girder in less than two hours using a single launching operation. The U-girders consists of two webs, each 6 in. thick, and a bottom flange with a thickness of 9 in. U-girders were post-tensioned using seven bonded tendons in the bottom flange with 37-in.-diameter strands. Each U-girder top bulb girder includes one 13-strand tendon. This arrangement guarantees compression across the joints after transfer and for service loading. All tendons were stressed to up to 80% of their breaking load.
Overcoming several obstacles, including difficult installation conditions, massive size considerations, and even a pandemic, this record-setting precast UHPC bridge is set to serve the industrial park where it is located—and the surrounding community—for years to come.
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |