Photo Source: Doc WSBP
A girder is a beam made of concrete or steel placed within two supports in the form of a pear or abutment, and is used as the main horizontal support of a structure that supports smaller beams in construction.
Based on its type, there are shaped concrete blocks or also known as PC-I Girder. What's a PC-I Girder and how is it made?
Apa Itu PC-I Girder?
PCI girder is an abbreviation "Pre-stressed Concrete I-Girder “, which can be interpreted as an I-shaped prestressed concrete beam. PCI girder is a structural component commonly used in bridge construction.
PC-I Girder is made concrete pre-stressed concrete, which means that the concrete inside is stressed before ready to use. This tension is given through a series of prestress cables embedded within the concrete. This prestressing process helps to increase the strength and stiffness of the girder, so it is able to withstand loads that are applied to the bridge construction.
The “I” shape on a PC-I Girder refers to the cross-sectional shape of the girder that resembles the letter “I”. This shape is chosen because it has a good strength in withstanding vertical and horizontal loads. Other than that, the “I” shape also allows for an efficient installation of girder using lifting equipment, such as a a crane.
PC-I Girder are often used for bridge construction in Indonesia due to their advantages. Some of them include high strength, ability to withstand large loads, good rigidity, ease of installations, and more economical.
Practically, PC-I Girder are installed simultaneously and connected to each other to form the main structure of a bridge. This will support the bridge floor and distribute the loads to other supporting structure, such as poles or columns.
How is Production of PC-I Girder?
PC-I Girder production involves several stages. Here are a more detailed explanation of each stage of the PC-I Girder production process:
1. Beam Detail Drawing and Material Specification
Beam Detail Drawing and Material Specification are crucial in PC-I Girder production because this stage provides clear and detailed guidance for the production team.
Beam Detail Drawing helps in understanding the shape and dimension of the girder to be produced. Meanwhile, Material Specification ensures that the material used complies with the specified quality and strength value.
By following these steps carefully, the production of girders is able to be carried out with high accuracy and reliability.
2. Bed Setting
In the PC-I Girder production process, “bed setting" refers to the process of preparing the place or location where the girder mold or shape will be placed for the concrete casting process.
First of all, a suitable location must be selected to carry out the girder casting process. This location is usually located within a factory or production facility that is specially prepared for making girders.
Once the location is selected, bed setting stage involves preparing the place where the girder molding will be placed. Bed is commonly made of a strong and reliable material, such as concrete or steel. Bed must be designed and built in such a way that it is able to withstand the weight of the girder mold and the concrete mix that will be poured inside it.
After the bed is ready, the girder will be placed on top of the the beddingThis mold is usually made of steel or concrete and assembled according to the planned girder dimensions and shapes.
The mold must be placed precisely and arranged according to the approved Beam Detail Drawing.
Before casting the concrete, prestressed cables that will be placed within the mold must be prepared. This cable will be placed inside the mold according to the location and specifications specified within the design. The cable must be tied with proper tension and checked well to ensure the strength and stiffness of the produced girder.
3. Beam Reinforcing
“Beam reinforcing" is a production process of PC-I Girder according to the addition of reinforcement or reinforcing steel placed inside the prestressed concrete girder.
This reinforcement steel aims to increase the strength and stiffness of the girder and also provide additional support for the loads applied to the girder.
With this additional reinforcement steel, prestressed concrete girder will become stronger, resistant to loads, and able to withstand deformation or crack that may occur due to the applied load. Reinforcement steel also helps to maintain the structural integrity of the girder in a long term.
4. Ducting Seath Setting
“Ducting Seat Setting" stage is a process of preparing a place or position within a prestressed concrete girder where ducting or channel for the prestressed cable will be placed.
This stage is essential in the PC-I Girder production process, because it ensures ducts are positioned correctly within the girder to accommodate the prestressing cable.
A proper ducting seat placement ducting seat will ensure that the prestressed cable is able to be pulled or tightened easily and in accordance with the desired structural design.
With a good ducting seat setting a good ducting seat setting, the prestressed concrete girder is able to have a pre-stressed system that functions effectively and provides a strong structural support.
5. End Plate & Steel Pin Setting
End Plate & Steel Pin Setting is the stage of preparation and placement of end plate and steel pin on prestressed concrete girder. End plate and steel pin are placed on a pre-stressed concrete girder according to the approved structural design.
With proper placement and strong connections, end plate and steel pin ensure girders are connected effectively with other structural elements, such as columns or support beams. This is important to maintain structural integrity and girder strength and also ensure that the girder is able to withstand load safely and stably.
6. Formwork Closing
“Formwork Closing" is the closing stage or locking of the formwork after concrete girder casting is completed. Formwork closing involves actions to secure mold so that the concrete can be hardened well and take on the desired shape.
7. Concreting
“Concreting" refers to the stage of casting concrete in molds to form prestressed concrete girder. This is a process where fresh concrete is poured into a mold and given time to harden and form a strong girder structure.
8. Formwork Dismantled
“Formwork dismantled" is the stage where formwork used for casting prestressed concrete girder is removed or dismantled after the concrete has reached sufficient hardened level. This is a process where formwork formwork is lifted or split in order to reveal the finished girder.
9. Conc. Curing dan Segment Stacking
After casting the girder concrete and completing the formwork closing, the next step is concrete curing and segment stacking.
Tahap The concrete curing stage or concrete hardening is essential to achieve the desired strength and quality of girder. Meanwhile, Segment Stacking, girder segments are joined as one and prepared for installation in the project site/field. Both of these stages ensure that the prestressed concrete girder is ready for use and comply with the required strength and performance.
