What is Structural Engineer?

Draftsmen draft. Just kidding. They do draft but they are better than that, well! Some are. The need for a draftsmen might be meek in an ideal European sense, with all the automations and sort. Even without the automations, a Structural Engineer is expected to be able to do the drafting himself/herself.  But I don't live in Europe, do I? And the need also arises due to the sheer scale of some projects. The main task of Engineers is to design and analyse the structures. And it does take time. Hence, the need for draftsmen. Now what does a Draftsmen do. They draft. They are expected to be good in drafting softwares, whether it be 2D, 3D or even 4D. Though I have never been a part of a 4D project YET. Some general softwares can be the CAD lineup, Revit, Dynamo, Sketchup and the list goes on.  They should have the knowledge as how it all works. Some cases are not always general, and they have to come up with alternatives, just like Engineers in this case. For example, I had to imp...

This is one of the coolest concepts I have properly learnt at my job. I do know I will learn lot more on this. It's the Stiffness Modifiers.  It is a modification factor that is generally used in the properties of cross-section such as Moment of Inertia, Shear Area, Torsional Constant etc. It can also be used for Mass and Weight as per requirement. Modifiers for a typical Beam. Now why is it used? As the loads act on the structure, it will tend to generate cracks on the tension zone. Thus, reducing the area of cross section and stiffness of the member. 1 means the structure would take all of the loads, while 0 won't be taking any. It is kind of a paradox; the structure would resist all the loads if it is not cracked, and we know it will crack. In other way, we want the structure to not take the load as it will eventually crack. Concrete is weak in Tension. As per codes, IS Code ACI Code Now I have two great examples for putting my case. One is related to a torsion modifier I st...

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...

 I have been super busy the last three weeks. We had a submission, a Detailed Design submission, you don't have to know what that is. So, I didn't have enough time to sit down and pen my thoughts carefully. I have the resources though, both theoretical and application wise.  Today's blog is an update that I have completed my first project as a Structural Engineer. It is a mall at Sharjah, by the name ALJADAH. You can google, it's pretty, at least Architecturally. It wasn't the smoothest of projects, that's what my mini bosses told. It's my first project, who am I to judge? I learnt few things down the process. I got to learn technical structural things, but also the working of a corporation. But maybe, it is what it is.  Ow! why do you have to google it. I will attach the image here. See how pretty it is. But it was such as dreadful for us Engineers. I don't understand the Architecture urge to make changes as fast as they do. Some interesting takeaways f...

It's always good to read about the works and words of the people before us. And I come across lots of writings which suggests the importance of hand/manual calculations to cross verify the results by a software. It usually goes like this : " Whenever I ask a beginner/trainee whether he checked it manually, their answer is usually NO". Manual calculations are a must, but if it's just a calculation, what better than a computer. So it's more important to understand how the software works and gives the results of an analysis/design. ETABS is a software by CSI. It is an integrated software for the structural analysis and design of buildings. It is like an standard in the construction industry. But it is a tool, which gives the results as per the input and it should not be taken at a face value. This series will be updated as per my experience and discovery of the working of the ETABS software. There are manuals for its working for sure. But what good is a manual if you...

As an engineer, Iterations is a part of you. Until you have the required experience, it is one of the best ways to learn and understand the trade. I do believe Senior Engineers require their share of iterations too. For me, it's the endless analysis of structural models.  Don't mind my naming of the files. Lucky for us, we have software to do the work for us. Now you might ask why we don't just do the work with the codes and the books, the manual way. In a way, it is nearly impossible to design a whole structure just by hand calculations. It would take too much of our time and the transfer of Reactions might not be accurate. REACTIONS are what the building/structure would experience when it is subjected to different loads. I did explain, ever so slightly about the loads in my first blog. As a rookie, my task is to check whether the reactions are within the allowable limits. For this, the first task is to model the building in the software, then the model is subjected to the...

"Every other profession has its final product. A car manufacturer has the new model, a singer has her songs, a developer has the line of codes. For us Structural Engineer, we have our drawings, detailed by the analysis and design." That's the pep talk our Head of Design Unit gave at the short welcome orientation.  So today, I will be writing about the first task, other than the training ofcourse, I did after joining the company. It's called Beam Schedule. It's one of the final sheets we deliver the contractor/client. BEAM SCHEDULE: Beam Schedule is a table which informs a contractor of the required beam types in a building. It gives the quantity, size and the different beam types in a particular building. The number of reinforcing bars, stirrups/cadre required for each type of beam and the spacing between the bars. The table is an end product of a long iterative process, and it should be taken as such. The size of a beam is given in terms of its Width x Depth. You...

 Lately, I have been asked of what I do as a Structural Engineer. So through this post, I will explain my understanding of the world of Structures. A lot of people think that Structural Engineering is merely a branch of Civil Engineering. It is kind of true, Civil Engineering is quite vast given its early introduction compared to other branches of Engineering. But to be fair, it should be treated as a unique branch of Engineering. Some of the concepts and theories that Civil Engineer learns is applied and extended in Structural Engineering. In India, one can go for Masters in Structural Engineering. It has a deep connection with Science and Mathematics. It is closely related to Architecture, without their infinite imagination. It is founded on logical and analytical thinking.  Given the early introduction, it has been quite researched and exploited too. Thus we have code books which is our Bible. The work of a Structural Engineer can be put under two categories: Analysis and D...