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| Perspective view at night. Entire top floor is enclosed with a curtain wall, and about 50% of the ground floor. |
LOCATION: WHERE, WHAT & WHY?
For this assignment, our group decided to research on Jibby & Co. The component I decided to write about are the curtain walls of the building. We had to come up with an infographic as a group, and sketch out the findings we respectively did and blog about it for our individual task.
One of the most striking structural components of Jibby & Co are the glass walls, which are known as curtain walls. I chose this component because it is unique and beautiful.
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| Scale drawing I did in photoshop after tracing pictures! |
WHAT DID I RESEARCH?
Curtain wall system refers to the outside covering of a building, where the infill walls are non-load bearing and function as a barrier from weather, and to enclose the space. Glass curtain wall systems also provide aesthetic appeal. As exterior walls require a load bearing structure, curtain walls are an easy and beautiful solution for those who want to use non load bearing materials for the walls. Glass curtain walls contribute a lot to the ambience due to the fact that it allows a lot of natural light to enter the premises. The system here is slightly slanted to improve its structural strength.
Curtain wall systems are comprised of the infills, mullions, rubber gaskets and exist in tandem with other structural components such as beams and columns.
INFILLS
The infills of the system used here are insulated and laminated transparent glass. Standard 1 inch thick insulted glass panels are used, which is made of two 1/4 inch kites of glass with 1/2 inch airspace. The air used inside is usually an inert gas such as argon to provide thermal insulation against direct sunlight. Noise from ongoing construction works in the area is also lessened due to the insulation. The glass is also covered with a laminate which in this case is used to limit harmful UV rays from penetrating through the glass. Laminate can also increase the lifespan of glass protecting it from damage caused by physical forces, and scratching. The glass used may not be load bearing but is tough enough to withhold any forces applied by human physical force.
There are secondary panels included in this system which are made of aluminium louvres, which exist for aesthetic value and provide minimal shade. Other options for infills could be veneer, zinc panels, plywood, operable openings such as windows or vents, and many other materials.
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| Standard insulated glass section diagram. Courtesy of G. James Glass |
MULLIONS
The glass is held together by the frames which are called mullions. Aluminium is easily extruded into any shape easing the manufacturing process of the frames. The aluminium mullion frames used here are anodized or painted to prevent corrosion. It is lightweight, affordable, low-maintenance, durable, high tensile and compressive strength, and not susceptible to damage caused by rust, vermin attacks, and fire. The framing system used here is called the ‘stick system’, where infills are placed next to each other supported vertically with the frames.
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| Example of curtain wall system. Jibby & Co. uses a different system but I had to refer online to understand various systems better via examples. |
GASKET
The infills are attached to the frames with a rubber gasket to hold everything in place. It also allows expansion to occur without causing damage, and eliminates water penetration. Deflection caused by various factors such as thermal expansion (as aluminium has a higher modus of elasticity and expansion than steel) must be calculated during the designing process and is accounted for by adding gaskets.
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| Gaskets for sale at AliBaba.com |
LOADS
The infills of the wall are non-load bearing but the system itself with adequate framing is structurally load bearing. How the curtain wall handles the loads depends on the materials chosen, design, and quality of materials. Here is how it handles the various loads:
- Dead load refers to the weight from the structural element itself and the permanent features of the structure. The dead load imposed on the curtain wall come from the weight of the components itself, and the roof. Due to good designing of the frames and presence of other elements such as beams and anchors, the curtain wall is sturdy in this instance. Other loads imposed on the curtain wall, such as sunshades, must be accounted for during the design process.
- Wind and rain load refers to forces applied from external wind pressure due to the weather. The curtain wall resists tropical winds and storms quite well, protecting the building. This is due to the structural strength of the wall, and tough glass used, slanted reducing wind resistance.
- Seismic load refers to the force applied from movements in the earth. In many situations, this curtain wall system is able to withstand seismic and wind induced building sway because of the security provided by the gaskets placed between the gaps between the infill and the mullion. Standard curtain wall systems are able to withstand 75 mm of swaying movement without glass cracking or water leakage.
CONCLUSION
In conclusion, I learnt a lot on how to apply these features into a structure, and it goes to show that a component may serve equally well with form and function.
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| Close-up view of the curtain wall from inside. Note the slanted angle. |
