They reach toward the sky like gargantuan metal fingers sprung up from the ground. They are, of course, skyscrapers. They are the quintessential towering monoliths of cities the world over. More fascinating even than their appearance is the method of their construction and the detailed engineering that allows them to stand so prominent against the skyline.
Skyscrapers account for many of the tallest buildings that exist in the modern world. Due to the immense size and cost of construction, meticulous architectural design is paramount even before construction begins. Electrical engineers must take environmental factors such as high winds, storms, and earthquakes into account. In addition, these engineers must consider vibrations, loading, and manmade disasters and accidents in their calculations.
Solid construction works from the ground up, beginning with the substructure which reaches down to the solid bedrock. This is the only way to have a foundation robust enough to bear the load of such an enormous building. Upon that smoothed bedrock the foundation is laid and the superstructure is built.
As the building gets taller, wind and other natural hazards grow in concern because of loading. Loading is the term used to describe the stress placed on the material in a given direction from a given source. The dead load is a vertical load, or downward stress, on the material from the material above. That is to say, the weight of the building above bearing down on the building below. The wind load is a horizontal, or sideways, stress that increases as the building gets taller. To account for loading civil & mechanical engineers utilize special designs for skyscrapers. The most common categories of skyscraper structure design are shear walls, steel frames, and tube frames. Each come with their own benefits and detractions, many of which are based on the standalone building‘s ability to cope with the stress of loading.
The sheer walls design boasts low material cost and fewer maintenance requirements. Materials in this design include plywood, brick, and cinderblock. The key element to a sheer wall design is that the taller the wall becomes the more weight the wall must be able to bear. This means that walls must be substantially thicker or wider to manage the stress placed on the material. Sheer walls are considered best suited for shorter buildings. This is because of the immense size and loads experienced by a skyscraper, which would inherently rob significant amounts of floor space as the walls must be substantially thicker.
Steel frame buildings are one of the oldest designs for skyscrapers. Originally imagined as a steel cube with other steel cubes inside, the strength of steel counteracts the thickness requirements placed on sheer walls. Horizontal and vertical supports are placed throughout the skyscraper, giving a high strength against horizontal and vertical loads. The greatest drawback to the steel frame design is its inefficiency above forty stories. As the building gets taller, the vertical load increases and so supports must grow closer and closer together. Past the forty-story mark, supports must be so close that significant floor space is lost, and the design of the blueprints is no longer economic or practical.
Tube frame structures are three and sometimes more frames connected and built in a tube shape. The interconnected superstructure can withstand force from any direction and reduces the need for interior support columns. This provides greater floor space while allowing greater height than steel frame structures. Multiple variations of the design have sprung up over the last century, and even today the tallest buildings in the world use elements of the tube structure design.
The final major design element for a commercial building architecture design are elevators. Without these machines, individuals would need to climb several flights of stairs to reach their destination. While essential, these inter-floor transporters also rob valuable floor space. So, civil engineers regularly battle with putting in the right number for efficient movement, while maximizing the economics of the building.
No matter which design is used, there is little doubt about the remarkable structures that make up big city skylines. Skyscrapers are iconic modern marvels, specially designed and carefully laid out to accommodate offices and penthouse suites alike while enduring the huge stresses that come with reaching up to touch the sky.