In this article, I will try to answer questions such as what is reinforced concrete curtain wall, where are curtain walls used, and what are the advantages.
Reinforced Concrete Shear Walls
Reinforced concrete shear walls; are at least 6 times the width of the carrier elements. In other words, if the width of a 30 cm thick carrier element is 180 cm or more, this carrier element is called a reinforced concrete shear wall.
Reinforced concrete shear walls; Just like columns, they transfer the loads they take from slabs and beams to the foundation. However, the issue that makes reinforced concrete curtains so important; is not that they transmit the vertical loads from the slabs and beams to the foundation. The issue that makes reinforced concrete shear walls so important; is because they make the building behave stronger in the event of an earthquake.
Think of it this way; Columns carry buildings under vertical load. However, the columns will remain very fragile in the face of horizontal loads (earthquakes, etc.). The structural element that responds best to horizontal loads is reinforced concrete shear walls.
I will give an example in terms of it to be in your memory and to fit your logic perfectly. Examine the photo below carefully. If the cabinet is single (column), it will be easy to overturn that cabinet. However, if the width of the closet is long ( reinforced concrete curtain ), it will not be possible to overturn this closet.
This is exactly the behavior of reinforced concrete walls against earthquake forces. Allows the building to displace (move) less. In this way, the building receives less damage.
Also, you must know about Reinforce Concrete before further discussion on the shear wall:
Definition of Reinforced Concrete
Before explaining what is reinforced concrete, first know the definition of concrete. Concrete is a mixture of fine and coarse aggregate materials consisting of sand, gravel, crushed stone, or other similar materials which are mixed with cement and water to form a rock-like mass.
Meanwhile, reinforced concrete is concrete combined with steel reinforcement with an area and amount of reinforcement that is not less than the minimum value, which is required with or without prestress, and is planned based on the assumption that steel bars embedded in the concrete can provide strength. pull as needed.
Some of the reasons that reinforce that reinforcing steel and concrete can work together to withstand loads, namely:
- The strength of the bond between steel and concrete can interact to prevent slipping on hard concrete;
- A good concrete mixture has watertight properties which can prevent corrosion of reinforcing steel; and
- The starting velocity figures between steel and concrete are almost the same, namely between 0.000010-0.000013 for concrete per degree Celsius while for steel 0.000012 per degree Celsius.
Advantages and Disadvantages of Reinforced Concrete
Reinforced concrete structures have several advantages due to the combination of two composite / mixed materials, namely concrete (PC + fine aggregate + coarse aggregate + additives) and steel as reinforcement. The following are the advantages of concrete as a building structure including:
- The ingredients are easy to get.
- The price of the materials is more economical and does not require high maintenance costs.
- Easy to shape according to the wishes of the architect.
- Reinforced concrete materials have high compressive strength.
- Reinforced concrete structures have a higher resistance to fire / high temperatures and water.
- Reinforced concrete can be molded into a variety of shapes, from simple plates, beams, columns to domed roofs and large shells;
Apart from the above advantages, reinforced concrete also has several disadvantages, namely:
- Reinforced concrete requires formwork to hold the concrete in place until it hardens;
- Reinforced concrete has a low strength per unit weight which results in heavily reinforced concrete.
- Working on reinforced concrete dough requires a reference (mold) and a scaffold (reference pole) for the duration of the work.
- Reinforced concrete has a low strength per unit volume, resulting in relatively large size concrete.
- The properties resulting from the production of reinforced concrete vary widely due to the varying proportions of the mixture and its stirring.
- The processes of making dough, pouring, and treating reinforced concrete cannot be handled as carefully as they do in the production of other materials such as steel and plywood.
Early Discovery of Reinforced Concrete
Concrete was first used in 1850 by a French citizen named Joseph Monier and Joseph Lambot. At that time, they were building boats and the concrete was given the bones of the iron comrades arranged in parallel. That’s why the two people are declared to be the inventors of the concept of reinforced concrete.
In 1867 Joseph Monier succeeded in obtaining a patent for the work he created. The work is in the form of a water storage pool made of concrete and given a construction bone made of woven iron bones. The use of this concept itself turns out to be able to produce a lighter construction but the concrete part still has maximum strength.
Since then, Joseph Monier has increasingly obtained patents from the use of reinforced concrete construction in larger buildings such as dams, bridges, and so on. Furthermore, a British citizen named William E. Ward in 1875 succeeded in creating a building using the first concrete bone construction in the United States. It’s just that, he said that the idea of making these bones came from manual labor or laborers in England. Two years later, namely 1877, Thaddeus Hyatt from America succeeded in analyzing the resistance of concrete to the heat of the fire.
On the other hand, EL Ransome who came from San Francisco in 1870 managed to find reinforced concrete in the form of threads. This invention was further patented in 1884 under its own name.
Development of Reinforced Concrete
Basically, reinforced concrete has a main character in the rolled section and uses a square shape, and is rotated or threaded in one turn. The length generally used is less than 12 times the diameter of the bone. That way the bonds that exist between the bone and concrete are getting stronger. From here, the concept of use and development of reinforced concrete technology continues to change with scientific advances and various innovations made by construction experts.
Currently, there are two calculation systems and principles used in calculating the load of reinforced concrete, namely WSD and USD. For the calculation of WSD using elasticity which is a comparison of the modulus of elasticity of steel and concrete. Meanwhile, USD is a calculation method based on the highest strength and durability of reinforced concrete against the level of flexibility of the bones.
Types of Reinforced Concrete Building Structures
Installation of reinforced concrete structures is divided into 2 (two), namely precast
(precast) and cast in place. If the installation of the building structure used is the casting method, then the reinforced concrete building structure is monolithic which can be useful in resisting earthquake loads.
Reinforced concrete in buildings consists of several structural elements, such as beams, columns, and floor plates and the following is an explanation.
A reinforced concrete beam is one of the structural components that function to distribute the loads from the slab to the column, which in turn is transferred to the foundation by the column. In general, reinforced concrete beams are cast monolithically with plates and are structurally reinforced single or double. As a result of being cast monolithically with a plate, the beam has a square cross-section, T, and L.
The column is part of the structural elements or components of a building that functions as a channel for loads originating from the load on the plate, the plate’s own weight, and the beam which is then transferred to the foundation.
A reinforced concrete plate is a structure made for needs such as building floors, roofs, and so on with a horizontal surface area. In this plate structure, the load works perpendicular and is distributed on the wall, beam, column, or ground due to its location which can be supported by the wall, beam, column, or can also be located directly on the ground ( slab on ground). The plane thickness (h) for the reinforced concrete slab itself is relatively very small when compared to the length/width span. Reinforced concrete slabs are divided into 2 categories based on the ratio of length between long spans (lx) to short spans (ly). If the ratio value of long span to short span is more or equal to two, then the plate is categorized as a one-way plate, and if less is considered a two-way plate.
What are the benefits of reinforced concrete shear walls?
- They meet the earthquake forces
- They carry vertical loads
- They make the building move less during an earthquake.
- They reduce the possibility of damage to structural elements (columns, beams, etc.) in the event of an earthquake.
What should be considered when designing a reinforced concrete shear wall?
While designing reinforced concrete curtains, some important details from architects to engineers should not be overlooked. One of them is that reinforced concrete curtain walls should be placed symmetrically in the building.
If the reinforced concrete shear walls are not positioned symmetrically in the building, the distance between the rigidity center of the building and the center of gravity will increase, and this will cause the building to experience torsion effects during an earthquake. This is undesirable. For this reason, reinforced concrete shear walls should be designed as symmetrically in the plan as possible.
Because the earthquake force affects the building from the center of gravity. However, the building reacts to this force from the center of rigidity.
In addition, another point to be considered during the design phase; is that the beam and curtain connections should be made from the head area of the curtain, not from the body area of the reinforced concrete curtain walls. This issue is an overlooked issue.
To connect the beams to the curtain from the head area of the curtain, it is necessary to enlarge the head area of the reinforced concrete curtain from time to time.
How many cm should the reinforced concrete curtain thickness be at least?
According to TBDY 2018, reinforced concrete wall thickness should be at least 25 cm. This means that the smallest reinforced concrete curtain size is 25×150 cm.
What is an elevator curtain?
You may often hear the term elevator curtain. Actually, it is not something you do not know, but the polygon curtain that surrounds the elevator is called an elevator curtain.
What is a polygon curtain?
We learned that reinforced concrete vertical elements with a width of at least 6 times its length are called curtains. However, we always think of this concept as rectangular. However, the curtains are L-shaped, T-shaped, U-shaped, and so on. maybe. In this way, polygonal screens are called polygonal screens.
What is a basement curtain? What is the plinth curtain called?
A basement curtain is built-in basements that are below the ground surface. Basement curtains do not continue throughout the structure and are only located on the basement floor. Basement curtains also have many static benefits.