2.0 SPECIAL PRODUCT (Bebo arch and concrete railway sleepers)
Special product is a produce that products where not all industries are able to produce these products. This is because most industries lack equipment or hardware to produce such products. Among the intended products are bebo arch and concrete railway sleepers. One of place capable of producing bebo arch in Malaysia is Hume Concrete Sdn Bhd located in Beranang Selangor. They also make concrete railway sleepers for railway in Malaysia. Now, they are getting orders for the Mass Rapid Transit (MRT) and Keretapi Tanah Melayu Berhad (KTMB) projects.
Hume Concrete has equipment capable of producing bebo arch in small quantities which is 2 bebo arch per day. Regularly, orders are within 100 pieces per batch and mostly two or three pieces of bebo arch (3%) is rejected because it does not fulfill the requirement by the client. Bebo arch is system is a standardized patented precast concrete arch system for the design and construction of earth overfilled bridges, tunnels, culverts, other underground structures , as crossing structures over waterways, as overpass or underpass for roadways and railways and as protective structures for example shelters for aircraft and bunkers for munitions . The bebo bridge concrete arch system is a combination of cast in place concrete footings, precast arch elements, headwalls, and wing walls. The system uses the fundamentals of soil structure interaction to achieve superior strength and stability . Standard span ranges from 3600mm to 25600mm and longer span is upon request by the client.
FIGURE 2.1: Product (Bebo arch)
Bebo arch system have its own advantages in economy, speed and quality. In economy, the arch sections are slender in design which results in material savings for both concrete and reinforcing steel compared to traditional applications such as box culverts or beam frame type structures. Reduces maintenance costs and lowers life cycle costs as there are no bridge deck or joints at the deck or roadway interface . Bebo arch need moderate requirements for back and overfill material result in a cost effective construction procedure . It is also aesthetically pleasing & environmentally friendly . Besides, fully pre-engineered arch design to various design codes result in quick turnaround times for the complete structural design. Rapid installation results in reduced overall project costs, delays and detours. Apart from that, the bebo proven quality, structural integrity & durability. Bebo structures have no exposed bridge deck, no transition joints or approach slabs and no moving bearings the look of the true arch shape is always well received by officials, private property developers and the public. Overfilled reinforced concrete arch bridges are extremely durable and require virtually no maintenance (low life-cycle costs). Manufacturing is fast and efficient allowing us to offer a high quality yet cost effective bridge option.
FIGURE 2.2: Moulding for Bebo arch
Moreover, concrete railway sleepers becomes one of the famous product in Malaysia. This is because Malaysia government want to increase the quantity of railway in deep and remote areas. Sleepers are transverse beams laying on ballast and support. Wooden sleepers were utilized as a part of the past in light of the fact that timber was promptly accessible in the neighborhood. Nevertheless, restressed or reinforced concrete sleepers, and to a restricted degree steel sleepers, have been received in current railway tracks over the previous decades on account of their strength and long administration life. Solid sleepers are depicted as either twin-square or mono-piece. Inside all these sorts, concrete sleepers are all the more generally utilized in light of the fact that they are not influenced all that much by either atmosphere or climate. Furthermore, it provides anchorage for the fastening system and limit longitudinal, parallel and vertical movement by implanting itself onto the substructures. There are two types of concrete sleepers which are mono block concrete sleeper and twin block concrete sleeper . Railway sleeper that has been used at Hume Concrete is mono block concrete sleeper as in Figure 2.3 below.
Figure 2.3: Mono block concrete sleeper
In addition, Concrete railway sleeper is apply at mainline, turnout, cross over tracks as level crossing sleepers and ballast top bridge decks. It is also give advantages to us. Concrete railway sleeper is more durable having greater life up to 50years. It is economical as compare to wood and steel. Concrete railway sleeper is easy to manufacture, not susceptible to vermin attack, not susceptible to fire and it is good for track circuited areas.
In contrast, prestressed concrete railway sleeper or railroad ties is one of the design of concrete railway sleeper. It is principally designed in order to carry wheel loads from the rails to the ground. Their design takes into account static and dynamic loading conditions. It is evident that prestressed concrete has played a significant role as to maintain the high endurance of the sleepers under low to moderate repeated impact loads. In spite of the most common use of the prestressed concrete sleepers in railway tracks, there have always been considerable demands from rail and track engineers to improve serviceability and functionality of concrete sleepers. For example, signaling, fiber optic, equipment cables are often damaged either by acute ballast corners or by tamping machine operation. There has been a significant need to redesign concrete sleeper to cater cables internally so that they would not experience detrimental or harsh environments. Accordingly, this study is the world first to experimentally investigate the effects of holes and web openings on structural behaviors of concrete sleepers under rail loading condition. The modified compression field theory for ultimate strength behaviors of concrete sleepers will be highlighted in this study. The outcome of this study will enable the new design and calculation methods for prestressed concrete sleepers with holes and web opening that practically benefits civil, track and structural engineers in railway industry .
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2) Contech Engineered Solutions. Bebo BridesConcrete Arch System. Retrieved May 1, 2018 from http://www.conteches.com/products/bridges-and-structures/precast/bebo-bridge.
3) Hume Concrete Sdn. Bhd. Hume Bebo Arch Product. Retrieved May 1, 2018 from http://www.humeconcrete.com.my/index.php/features/bulk/bebo-arch-system.
4) Kahawatta Gamage, E., Kaewunruen, S. & Remennikov. Design of holes and web openings in railway prestressed concrete sleepers. Retrieved 4 May 3, 2018 from http://ro.uow.edu.au/cgi/viewcontent.cgi?article=6291&context=eispapers.
5) ScienceDiret. Prestresed concrete railway sleeper. Retrieved 3 May, 2018. From https://www.sciencedirect.com/science/article/pii/S1877705816327679.