What is Structural Engineer?

This is a photo I took during my visit to Indore. It's at the Devi Ahilyabai Holkar International Airport, but you could see this type of connections at every airport. I tried explaining my elder sis why is it so back then, but I might have been wrong. So here it is,  the correct answer. If you look closely at the connections, you can see that it's not welded or fixed like the smaller ones at the back. The reason is that it allows rotation on that particular connection. One might ask why would you allow rotation in the first place, isn't it dangerous? But wait, I will explain why is it so. Reactions in our world means how an object would respond to a certain load. If you squeeze a sponge, it gets flattened. So Reactions are basically responses. And if you don't want that particular response, you just allow it to be effected. Alright, it's not a very good explanation. I will try again. Take an example of catching a ball, the impact on your hand is nullified if you pu...

This is in Continuation to the ETABS_ 1 blog regarding the Shear Check of Beam.  The first post was only about the Shear Check. I rechecked the Beams for Shear and it passed as per my calculation. But the software showed otherwise. That was because of the additional external Torsion which I added to the beam. The Torsion in the Beam was added due to the Hollow Core Slabs which is supported on Beam ledges.  As per IS code , the torsion is converted to shear. Using clause 41.3, the equivalent Shear is calculated as, The torsion has been converted to Shear, it is therefore taken wholly by the Stirrups. Only the transverse reinforcement takes the torsion.  As per ACI 318-19 , the torsion reinforcement is provided in both the directions, clause ACI 22.7.6 But here's the catch, the point I am trying to make. There is an upper limit of the combination of Shear and Torsion that can be carried by the section. This is given in clause ACI 22.7.7.1a. This can also mean that the beam ...

                              If you look at it the right way, that's the whole of Seismic Analysis as per ASCE 7-10. 10 means the year of publication, the latest is 7-22. There are three important factors here, R = Response Reduction Factor, Omega = Overstrength Factor and Cd = Displacement Amplification Factor. Today I will be writing about the later one. Now it has to be seen as per Linear and Non-Linear Analysis. After a certain level of strain, the structure goes into a state of Non-Linearity, where there is more strain/deformation in structures over the increase in stress. In a perfectly elastic state, the change in uniform. If one wants to do linear elastic analysis of a structure under full seismic loading, the resultant forces will be significantly large, as seen in the graph, and the design of the structure will be uneconomical. We are not taking advantage of the of ductility and inelastic energy dissip...

To be honest, I don't really know much about Skyscrapers, not as a Structural Engineer. But what do I know a 100 %. So this blog is more like a rant about my interest in it.  Skyscrapers are super tall structures. You can see it in almost every top cities, I have only been to one YET. It is possibly the best way of utilising the minimal overly priced plot of land in a city. And it has been a game changer since its introduction. It makes the city skyline pretty too, in a way. A building is considered a skyscraper if it's taller than 160 meters, with more than 50 percent habitable. What this means is that more than 50 % of the building should be occupiable by humans. Take for example, The Eiffel Tower is a gigantic structure of 300 meters, but people can't stay there, hence a tower. The other 50 % could be aesthetics, to make it look cooler and dominant. This I learnt from the B1M podcast. To the Design aspects. At a height of more than 160 m, the winds play a crucial role. T...

Forces here means Reactions. Forces just sounds way cooler. The reactions are the responses by the structure to a load. It can be Axial Forces, Shear, Moment and Torsion.  Now what is Stiffness? It is the ability of a member to resist deformation under bending. It highly depends on the Moment of Inertia around the axis of Bending. Please be reminded that it's the Area Moment of Inertia and not Mass Moment. For a Solid Rectangular Cross Section, Moment of Inertia = b*h^3/12. Onto the deliveries, below is an ETABS model of the same plan with two different thickness profile.   A. Raft of equal thickness.   B. Raft of different thickness. B has a raft of 400 mm with a thickening of 1500 mm near the edges. This thickened portion will support the wall from above.  Now we analyze the model for the same loads and loading combination over the same process. I have taken the M22 case for comparison, but any other reaction would have been fine. A. B. As we can see, the reactions...

Suppose you have a foundation at two levels. The foundation of the structure is at two different heights/elevation, A and B. And the two are connected by a wall.  The scenario. The wall will start from the lower foundation B and so it will be monolithically connected with it. Thus, you will have to model it accordingly.  Whereas A can be modelled and designed in two different ways: The two approaches. One where you place the foundation over the wall. But then the foundation would be able to move sideways in case of horizontal forces, like the first image below. To avoid the horizontal movement, it is designed to be monolithic by providing the required reinforcements. And it becomes a normal wall slab connection design, the third image below.                                    Another way to go through it is by placing the foundation on the top level of the wall. Case II among the two appr...