### Building a 3000m tall building..!! Is it possible?

Fun stuff...!!

A 3000 m tall building is definitely possible. Let us say we have infinite sum of money. Just for the sake of simplifying things so that we can focus on engineering. Challenges?

1. Wind
A structure this tall will be under a giant amount of wind force and I am not saying that it is not possible to resist, we can resist it, but with intelligent engineering. In such cases wind tunnel tests are conducted and the shape of building is put up in such a fashion that we can reduce the wind forces. For example, the current tallest building of the world, Burj Khalifa is standing under the same principle.

As Will Baker (Bill Baker) says that, the design of the tower is such that it confuses the wind force. The wind force increases as the height of the tower increases, and if the building height is like that of Burj Khalifa, than the allowable deflection is 3m or so which can make the people inside the building uncomfortable. So what they have done is, they have regularly changed the profile of the building so that the boundary layer of wind that is formed around the building is the turbulent one. Also the wind that is flowing will get confused with height because of the change in the shape of the structure. This reduces wind force drastically and helps the tower to remain upright. The lateral forces are simply carried by the tower frame and spinal wall system. This is the most innovative thing that I have seen in my entire life. I did a final year project on wind forces and profile around the structures and found that it is actually the best way to reduce the wind forces.
Apart from this we can use things like Tuned Mass Dampers which can help in reducing the wind induced deflections at the top. It is just a big chunk of mass suspended at the top of the building which works in direction opposite to the motion of the building. Taipei 101 has a TMD which can help in reducing the story displacements or you can say story movements.

2. Earthquakes

As we all know how devastating earthquakes can be. But don't worry, taller buildings perform better and show much more anticipated deformations during earthquakes than a shorter building. So we can design such building pretty efficiently with accurate runs. Before even such building is built, we can test the structure for an actual earthquake and see if it will resist the forces or not.

For resisting earthquakes and wind we use something called Lateral force resisting systems which can be huge walls in the center and massive columns around the perimeter. Definitely the wall will utilize tremendous amount of space, but anyway we will require such space for 1 reason. Vertical Transportation

3. Vertical Transportation

You know it takes around 10 minutes to reach the top of Burj Khalifa, that it is the highest occupied floor located at 585 m from the ground? It is because no single elevator goes from bottom to top. You will be switching elevators as you switch metro trains. So imagine the same thing for a 3 km tall building. We will require many more elevators with transfer levels. In a building like Burj Khalifa there are 57 elevators. So in such building we will require anywhere around 150-175 elevators assuming that the elevators are much more faster than ever used till now.

Thus in order to provide these many elevators and stairs so on, we will require a huge central space around which we can construct a core wall or a Lateral force resisting system. If you do not know what LFRS system is, here is a picture as an example:

The central network of walls is called shear wall or core wall system. These massive walls can resist the lateral forces.

4. Strong soil

Now, if you have to stand strong and tall you require strong foundation. This foundation will be a combination of a Raft and piles. The foundation will be around several feet thick and the piles will be drilled at least 150-175 m deep into the soil. This will make the total depth of foundation equivalent to 175-200m deep from the lowest floor. I am saying lowest floor as the building is so huge, it will require several stories of parking. The foundation of Burj Khalifa which is 828m has piles driven about 50 m into the ground and has raft which is 3.7m thick. Now you can imagine why we require such a giant foundation. The foundation of Burj khalifa looks something like this:

The plate you are looking at is a Mat while the tubes are piles driven into the ground.

5. Parking

It has to be a mixed use building. This means you will require several floors of parking. And in order to make everything quick so that people don't have to drive 15 or 20 or 30 stories into the ground or above the ground, we will have to work with automatic parking system, where in you stop your car at designated location and a whole chain of automated machinery will take the car to an empty spot. This is the only way to make the system efficient. (Automated parking system) Many places have already adopted such parking system.

6. Fire

In case of a catastrophic fire we will have to think of something innovative where people don't have to come all the way down to the ground in case of fire. A concept of Refugee rooms has been adopted in tall buildings where in there are big fireproof rooms constructed at every few levels where people can lock themselves in and wait for firemen who can rescue them. Apart from this we will require strong pumps to pump water to the top of the building. It can all be done.

7. Construction

If you want to construct 3 km above the ground, you will have to pump concrete up-to that level. Now we have pumped concrete in Burj Khalifa and guess what, it is not up to 828 m, rather it is up to around 600 m. So we will face a tremendous amount of challenge to pump it up to 3000 m without letting the concrete dry. We have methods, but we need to improve those. Let us see till what level we can pump concrete in Jeddah Tower.

If we achieve these feats then rest of the problems are not so big. Imagination is a beautiful thing, it can take us anywhere, but it is reality that limits us.

Fun fact:
http://www.equipmentworld.com/is...

Enjoy.

1. Yes, construction of 3000m tall building is possible in this era. Your article is very informative and I liked your way to express your views here. If anyone looking for structural engineering design services, slabsc is the best choice.

### What is a Response Reduction factor?

In our previous blogs we discussed about  Response Spectrum Analysis ,  Earthquake and Energy Dissipation  as well as  Ductility demand in structures during seismic loading . In response spectrum analysis topics like mode shapes, modal mass participation factors, derivation of response spectrum we discussed. In earthquake vs energy dissipation blog, we talked about energy dissipated from buildings through strain energy, inelastic energy, hysteresis, damping and ductility. In ductility demand we discussed about importance of ductile detailing and how it helps a building to work during earthquakes just like a marathon runner during long runs.  Generally inelastic energy dissipation, damping energy, ductility demand and ductility capacity, hysteresis loops are all captured when a nonlinear model is built, and time history analysis is performed for the structure. But to do nonlinear time history analysis, it takes a long time to build a model. The performance evaluation and result ve

### Ductility and Elasticity

Ductility and elasticity,the two most important terms that are discussed frequently in structural engineering. Elasticity defines about how much the material is elastic, that is to which extent the deformations are proportional to the forces applied on the material. While ductility defines the capability of the material to get itself stretched beyond the elastic zone. Let me explain this by taking a real life example. Take a two different material, a rubber band and a very thin steel or copper wire.  Pull the rubber with your hands by applying the force in exactly opposite direction, and force means a tiny amount of pull. You will notice that the mount of deformations caused by the small pull is very large, but when you leave the rubber band it will come back to it's original position. This means that the rubber band is elastic in nature. Oh, now you got something in your bucket. But wait, here comes the question. Till what magnitude of force can rubber band behave in such

### Possible types of failures in a steel structure

We, structural engineers design all the members of a building, whether it might be a column, beam, a tie member or a strut anything, but we design it to resist certain forces. We predict a load, calculate forces in different members and design them member to resist a particular load. But sometimes because of some undetermined or unpredicted load the forced in certain members increase to a value which it cannot withstand and the LObmember fails. But what are the different possibilities of failure? How can a member fail? Don't worry, here is what we are going to talk about. The possible types of failures in steel structures. Steel is a ductile material and to build a structure using steel is like setting up a huge Jigsaw puzzle. You have 1000 different members and you need to connect them and tada..!! Your structure is up. But it is not as simple as it is visible. Steel being a very strong material  leads to slender members. Now you can imagine the difficulties associated with it