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premjit
Admin
Admin
Dec 16, 2021
In Civil & Structural Discussions
The titled question on pattern Live load is a structural doubt asked by a structural engineer on LinkedIn The doubt is based on IS 456 code provision. I thought of asking it here so that all civil engineering job aspirants will be benefited. The question was ''Today while designing one-way slab, I came across this clause I couldn't figure it out. Can you please let me know what does this clause meant?'' The fact is that the structural engineer who asked this load calculation related question is technically sound and actively discusses technical aspects. This underlines the importance of experience and learning by asking questions. He is surely in the right path. In this world where most structural engineers focus just on modelling in ETABS and all results interpreted from etabs. When it is absolutely fine and a requirement to use software for analysis and design, please note that such load calculations, pattern loading and various live load reduction and seismic mass calculations are all input in etabs. It is required that young structural engineers and civil engineers know about these code provisions Please discuss this in the Forum, and I will put up a video soon on this topic of Live Load Pattern Loading. I have written a Blog and also a Video on this topic of pattern load.Click here to see the Vlog
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premjit
Admin
Admin
Oct 12, 2021
In Civil & Structural Discussions
This is a question discussed in civilera course forum some time back. Is a RCC pedestal needing Reinforcement when it is molnolithic with columns ? A pedestal is generally a compression member. IS 456 also says that the effective length should not exceed three times the least lateral dimensions. What ever it is, if the column is modelled, analysed and designed for its full length as actual, then we are meeting the design requirement with the section of the column itself. The pedestal is then provided for 3 reasons To reduce the moment in the footing To reduce shear in the footing To reduce the Punching Shear in the footing I will write a separate blog on these 3 points some time later. Our current question is on the steel requirement in pedestal. The pressure from the soil subjects the footing to bend and the pedestal is compressed. The column itself is designed for a huge compression from the floor loads. Therefore the pedestal will need only a nominal reinforcement The Video below will give more clarity on this topic.
Do we need Reinforcement for Pedestals? content media
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premjit
Admin
Admin
Sep 28, 2021
In Civil & Structural Discussions
This is a question asked by a student in one of the learning groups and I thought it is worth posting in the general forum and also clarify a few additional points. Also, we can use this forum to discuss on this topic and on shear walls in general. The exact question asked by the student was ‘'In my office one of my seniors used columns and brick walls for lift instead of providing shear wall. Is that a safe practice?’’ This question on shear wall cannot be answered unless I explain what a shear wall is and what its behavior is and when it is effective and many other points on position of shear wall and its effectiveness to resist lateral loads. I suggest you read my blog here to know more about the answer to this question. Let me conclude one thing here. Do we need a wall around lift always? Let it be called a shear wall or RC wall, do we need a wall in concrete around the lift always or can that be masonry as the student has asked? The answer is that, lift point of view, it is not mandatory to have a RCC wall around the lift shaft. It can be a masonry wall also.The weight of the lift is not going to be taken by the walls. There might be a small lateral thrust due to the lift movement. This is not of a huge magnitude and the walls can take that. I have summarized all the points on shear wall in this blog Comment your questions or any other points that you have to discuss here
Can we use columns and brick walls around lift instead of providing shear wall? content media
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premjit
Admin
Admin
Sep 09, 2021
In Civil & Structural Discussions
This is a question often asked by young civil engineers. One of the student in the forum asked this question and I thought of answering this. The question was '' Can we place a sump tank on top of the footing''? His primary concern was that if this will result in excessive pressure on the footing. I have made a video for answering this point on additional pressure due to water tank. The video has 2 additional points in it in addition to answering if the water tank will excert additional pressure. A point on water proofing. A point on instability that can result if you are not careful. If you like to see more blogs and videos on Foundation related points, it is here which helps you on how to interpret a soil report and precautions that you need to take when there is a compressive soil in a project site. Please provide your comments below in the forum. Discuss all your questions on this point in the comment section.
Is it possible to have a sump water tank on top of a foundation?  content media
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premjit
Admin
Admin
Sep 03, 2021
In Civil & Structural Discussions
Many young civil engineers think all rebar laps has to be same. However this is not true. The lap of a rebar depends on a lot of factors. Some of it is listed below. Lap length depends on dia of rebars Lap length depends on the grade of concrete Lap length depends on the grade of steel rebars Many byheart the formula that lap length is 50 times dia of rebar. However it needs to be calculated. I have explained it in a blog.The link is provided at the end of this post. There is one more point to observe. Some times the lap length has to be increased more than the calculated value based on some conditions. One such condition is when the rebars are in direct tension. When will be a rebar be under direct tension? One example can be a suspender. Consider a mezannine floor suspended from a beam on top floor. The vertical member that suspends the below mezannine floor will be under direct tension. Any lap in that member has to be more. How much? Read this blog here to find out. You can also read another blog here to learn about lap length calculation Please like this post and the blogs.Comment if you have some thing to say. Share and spread a word. Note : You can signup in our site and be a site member to get the membership benefits in the future.
How much is tension lap length? content media
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premjit
Admin
Admin
Aug 25, 2021
In Civil & Structural Discussions
A question that can some times confuse an entry level civil or structural engineer! Generally, it is not needed to have a top reinforcement for isolated footings. Footings are subjected to the soil pressure and behaves as a cantilever and you need bottom steel for the footings. Also the footings are buried in soil and is not subjected to any temperature variation. So do we need top rebars for isolated footings? Here is a video that will completely clarify the requirement of top steel. You can discuss any additional questions if you have after seeing this video on the minimum top steel requirement for isolated footings. The rebards mentioned in the video has to be provided both ways at the top face of the foundation. Also read a blog on foundations here.
Should Isolated Footing need Top Reinforcement? content media
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premjit
Admin
Admin
Aug 06, 2021
In Civil & Structural Discussions
This is a question by a student that I am posting in the forum. '' I am having a general question that, when a cantilever beam is a part of continuous beam as in most cases ,the main steel of continuous beam is in bottom but in cantilever beam is in top so , the bottom bars of main reinforcement act as hanger bars for cantilever. But what if the main steel of cantilever is more than the top bars of continuous beam? And should we extend the extra bars of cantilever upto continuous beam or we shall bend it as per shown in one of your blog on Anchorage length? I am bit confused in this. Also the Development length formula doesn't give the length of back extension of bars of cantilever. So how do we calculate it?'' Basically the question is about two points. 1) In a continuous beam where the last span is a cantelever, and if the cantelever top steel is more than the requirement at the last span support, what needs to be done. Should the bars be separate and bent in to the column? 2) If not what should be the length that needs to be extended in to the beam behind. The question may not appear to be clear here. I suggest you take a look at the video to understand the question and its answer. I have tried to explain it and also provide more insights on how to use ETABS for better decisions on curtailment of rebars. You can also additionally read another question and a video here on a similar discussion. Join our discussion forums here.
How to decide Curtailment of Beam TOP Reinforcement in Beams? content media
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premjit
Admin
Admin
Jun 02, 2021
In Civil & Structural Discussions
What is a force envelope? Can we use a force envelope for structural design of column? Entry level Civil & structural engineers can use this forum space to discuss this topic. Many times, engineers are confused about the load combinations and how to interpret the results using force envelopes. Use this forum space to discuss every thing about loads,combinations and envelopes. Please see the blog and video on this topic HERE
What is a Force Envelope? content media
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premjit
Admin
Admin
May 28, 2021
In Civil & Structural Discussions
Civil Engineering will be more stronger if we engineers starts to propagate that Strength, Stability and Durability are as important end result to a client as much as it is Shape,Form and Shape. Clients give more emphasis to what is visible to them and Shape,Form and Shape is some thing that they can see themselves. Where as a Civil & Structural engineers work and the result they achieve for the client is invisible. It is our failure to communicate this to the end user that has resulted in the current deterioration of the profession Let us discuss a few things in this Forum 1) The problems faced by Civil & Structural Engineers 2) The reasons for the issue 3) Solutions for the issue Please be clear and precise to the point and be professional in the answers. You may have to create a log in/account to comment.
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premjit
Admin
Admin
May 27, 2021
In Civil & Structural Discussions
This question is asked by a student in our ETABS learning community.I thought of posting it in the general forum for the benefit of all the students visiting my website. The question is about a project he is doing and is about 2 points 1) About cantelevering a few slabs around a cutout. 2) About non availability of a tie for a column due to the cutout. The video in this forum post cater to both the questions and try to answer them. Basically, it is possible to cantelever slabs but all structural requirements for meeting a) Strength b) Stability c) Servicebility including deflections should be met. You can ask your questions by commenting here.You have to create a login/account to comment. You can join our workshop lists by subscribing Here
Cantelevering a Slab content media
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premjit
Admin
Admin
Apr 30, 2021
In Civil & Structural Discussions
A civil and structural engineers job is full of challenges.These challenges infact keeps the engineer and the engineering going ahead.All successful civil engineers have gone through challenges and the important point to note is that the successful ones enjoyed the challenges.Infact it is the challenges that drives an engineering branch as such.Those branches of engineering which are less challenged has remained stagnant.This is true for any sub branches of civil engineering too. Some times an interesting tool or an innovation might make a less challenged or a generic branch interesting and keeps it going.Otherwise those branches becomes a common mans job and it never will remain a specialist engineering branch. I will be clarifying about this in a future blog. The intention of posting this question is to gather your opinion on this topic and summarise later in a blog. Depending on the amount of information, this may be a series of blog like that of the blog we have on ''Structural Cracks'' which is planned as a series. Coming back to the question,I have already put together a few tips on the skills an entry level civil or structural engineer should posess in another blog here. The idea is to add on more points and make it a one stop place for reference for all civil & structural engineering beginners. Please comment your points in this thread so that it will be useful.Note that we are looking at every skill and not just technical skills in structural analysis using any software.
What are the essential skills a Structural or civil engineer should posess? content media
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premjit
Admin
Admin
Apr 23, 2021
In Civil & Structural Discussions
Reinforcement detailing is a very important step is structural design. It is the structural detailing that will convey your intended structural design to site. If your structural detailing of members is not good enough to convey what your design is, then there is no much use of the design. Many students focus on structural analysis and tools needed for it like ETABS and STAAD Pro Even knowing the tools that will help you to detail is not adequate. You need to know all the basic principles of rebar detailing to be the best structural engineer. Also remember that a client will not know what great analysis you have done or what optimisation in design you have done unless the drawing speaks for your design. A client sees only your drawing! So give adequate importance to it. You should be knowing why we need Minimum reinforcement in a beam and how much it is Why we need reinforcement at side faces if the web depth of the beam is more than 750 Why you are limiting the reinforcement to a maximum allowable percentage Why we restrict the spacing of rebars Why we stagger laps Why we need anchorage length Why some times we need additional rebars at openings In this vlog, I am discussing a question posted by a civil engineering student on two methods of reinforcement detailing for beams. He has sketched one detail with two rebars and another with three rebars in one layer. I have tried to explain most of the principles in this and hope you will learn something new from it. If you have any questions, please feel free to discuss in this forum threadReinforcement detailing is a very important step is structural design. It is the structural detailing that will convey your intended structural design to site. If your structural detailing of members is not good enough to convey what your design is, then there is no much use of the design. Many students focus on structural analysis and tools needed for it like ETABS and STAAD Pro Even knowing the tools that will help you to detail is not adequate. You need to know all the basic principles of rebar detailing to be the best structural engineer. Also remember that a client will not know what great analysis you have done or what optimisation in design you have done unless the drawing speaks for your design. A client sees only your drawing! So give adequate importance to it. You should be knowing why we need Minimum reinforcement in a beam and how much it is Why we need reinforcement at side faces if the web depth of the beam is more than 750 Why you are limiting the reinforcement to a maximum allowable percentage Why we restrict the spacing of rebars Why we stagger laps Why we need anchorage length Why some times we need additional rebars at openings In this vlog, I am discussing a question posted by a civil engineering student on two methods of reinforcement detailing for beams. He has sketched one detail with two rebars and another with three rebars in one layer. I have tried to explain most of the principles in this and hope you will learn something new from it. If you have any questions, please feel free to discuss in this forum thread by signing up/login.Your membership here is free until we reach a thousand subscribers. So hurry up. You can also book your limited webinar and blog list subsciption by joining HERE
Beam Reinforcement Detailing content media
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premjit
Admin
Admin
Apr 22, 2021
In Civil & Structural Discussions
This is a general doubt posted by beginners in civil engineering and who are starting to model or scheme building structures in ETABS or StaadPro. The kind of doubts civil engineering job aspirants have range from splitting a beam in model to deciding which is the main beam. Many believe that a column is needed at all beam ends. I had a similar question from a student about Primary and Secondary beam.I have elaborated this in a blog here so that it is clear to all readers.There is also a video in the blog that explains it in detail. I suggest you read the blog in full and then see the video for additional points. You can use this Forum space for discussing any doubts that you have on this particular topic. If you have any other structural design related question,then either start a new discussion thread in the forum or contact us here
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premjit
Admin
Admin
Apr 21, 2021
In Civil & Structural Discussions
Torsion in beams has been a confusing topic to many civil engineering students and structural engineering students alike. In the civil engineering text books , torsion is always dealt with an empherical formula as per the IS456 Most of the civil engineering professors also encourages to design for torsion in beams. However there are some very important basic points that are needed to understand before deciding to design for torsion.The way you look at this torsion is going to make your design economic and uneconomic. The concepts of Equilibrium Torsion and Compatibility torsion needs to be understood carefully and all compatibel torsions can be release there by making the design econmoic than what it will be if done by the emperical method. You can learn all about Torsion in one of our Blog Here. If you have any questions on this topic, Please comment and ask. Like and share this forum for better reach.
How you look at Torsion in beams decides economy content media
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premjit
Admin
Admin
Apr 18, 2021
In Civil & Structural Discussions
World Heritage Day is celebrated every year across the globe on April 18th in different ways. This is the International Day for monuments and sites . A day like this for celebration of heritage was proposed by International Council on Monuments and Sites (ICOMOS) on 18 April 1982.This proposal was approved by the General Assembly of UNESCO in 1983. The motive behind this proposal was to encourage understanding of the variety of culture,its heritage,their vulnerability and the need to protect the cultural Hertitge. Let us celebrate this day.Have put together a short video on Heritage Buildings in India in the above video. We have plans to extend our exploration to understand the Cultural Heritage of buildings in India. Please comment what we can do for the conservation of our Heritage Buildings in India. You can see our other blogs by clicking here
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premjit
Admin
Admin
Apr 03, 2021
In Civil & Structural Discussions
This is a question asked by an entry level civil engineer recently. Infact he had not thought about this all the while he was modelling in ETABS until he saw a real building. This is a familar story.Most civil engineering students focus on etabs modelling,staadpro tutorials and so on only on structural design software.While all these civil design software are useful,they are only good as much as you are.We need to know how to use it and how some design parameters are to be used in ETABS and STAAD and similar structural software. Some one following me might have seen me stating this many times.This is because its so much important to focus on things around you.So the next time you walk in to a building, see how it is schemed.See if you are able to visualise the structural load path and the system. Read as many drawings as possible,Structural,architectural,services and what ever you can get hold of. Go to site and see how buildings are build.This gives you more understanding and even more questions. Its the questions that should drive your each day! New questions,new answers,new structural challenges and thus new structural solutions.This dives our world. Here is a video that will answer the Question on modelling of inclined buildings in plan. If you have any questions on this topic,leave your comment here. It is these kind of structural topics that you need to focus if you need independent structural practice. If you are keen to see such important structural topics that you need to focus,see our blogs here If you like to get mentored in structural design by doing projects,see our structural design courses here
How to Model a building inclined in plan in ETABS content media
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premjit
Admin
Admin
Mar 25, 2021
In Civil & Structural Discussions
This is a Structural doubt on cantilever slab posted by a structural engineering intern in civilera structural community. I thought of posting this in this general civilera structural forum so that more civil engineering freshers are benefited. By following our forum and blog and actively participating in structural discussions here, you can learn tips and tricks in structures. In this structural question, the student wants to know about the possibility and options to support a particular slab that she has come across. See the sketch and video to understand this better. I also want you to understand that based on the situation and site conditions and the requirement, one or more or even a different solution may be workable. Also, all the designs should meet the strength, serviceability and stability requirements. So, don’t freelance structures unless you have enough experience or a mentor to guide you around with your doubts. The solution I have provided for this question also need some better understanding of load or moment redistribution. Redistribution is nothing but the load taking an alternate load bath deviating from the normal stiffness-based path when there is a slight lack of strength in that direct primary path. Code allows certain redistribution and if you don’t know about it, please check this blog Also, when the slab cantilever is at a different level there are chances of instability issues and the beam may be subjected to equilibrium torsion and you need to attend to it. You can read about torsion in beams here Also, the anchorage of the slab rebars is of importance especially when it is a freestanding slab with no back anchorage. Even if you have all the necessary strength and all other considerations attended in design, if the anchorage is not correct, the slab can fail in anchorage and can create an unforeseen disaster. This failure can be more sudden than we think and hence ensure we have proper detailing of rebars incase the cantilever slab is at a different level and is freestanding as I have explained in the video. You can also see two additional and similar blogs in our blog section. I have cross linked it below for your learning. One structural blog talks about the refurbishment of a slab. Refurbishment is nothing but strengthening or altering an existing slab or making any kind of structural modification to an existing structure. It could be even strengthening a slab for an additional load carrying capacity due to functional use change. Another similar blog is on a few tips when you have cut outs in slabs. That blog and video is very closely related to this question and can be useful to understand all about cutouts and how to tackle it in software like etabs. If you have more questions on this topic, please feel free to ask here and also initiate new discussions on relevant structural topics.
How do we support a cantilever slab? content media
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premjit
Admin
Admin
Mar 23, 2021
In Civil & Structural Discussions
How is this structure supported only at the edges? This picture is a popular discussion in many social media pages. The discussion is around the support of the the slab ''only at edgs'' I happened to see this when a student tagged me to the post and asked how is this supported. Thought of posting here for other students who may have a similar question. If you look at this closely,you can see that,it is a normal structural system.You probably have 150 to 200mm overlap and that is good enough to run 2 numbers through bars top and bottom.Thats a beam! I dont know the spans.However as long as the beam can have adequate depth appropriate to the span, this is possible.For aesthetics,the slab has the same depth as that of beam. See the sketches below for more understanding. You can see our blogs here You can join our mail list here and be part of our webinars and discussions
Supporting mechanism of a slab content media
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premjit
Admin
Admin
Mar 19, 2021
In Civil & Structural Discussions
This is a question from Vijaykumar,our student in the etabs course community. ''Beam Centre, Column Centre and External Brick Wall centres are different. Wall load acts as an eccentric load on to the beams since it is on the edge of the beam. In this case how this eccentricity is captured or modelled in Etabs?'' First point is that,this is a minor issue.The moment or the torsion induced due to this small load and minor eccentricity is not a huge one. Second point is that, the beam is rigid and it can be safely assumed that the load is transfered to the CG Third point is that in most cases the slabs are providing a tie action and is restraining the beams from rotation. Also the presence of slabs allows an alternate load path and hence there is scope for redistribution.This is a compatible torsion case and it is safe to release. We have explained all about torsion and releasing of torsion in detail in another blog on torsion and you can see it HERE and learn about equilibrium torsion and compatible torsion. If you have any questions or want to be in our mail list/forum/webinars,join HERE
In ETABS,How to account Wall eccentricity on beams? content media
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premjit
Admin
Admin
Mar 17, 2021
In Civil & Structural Discussions
I do a risk analysis of all projects I design. There can be accidents in buildings. It could be a blast, a terrorist attack, a small failure that can trigger a larger one and so on. Many believe accident happens to only others and risks themselves! Some believe such accident won’t happen. Now see this! A real un expected accident! That is how accidents are!! I have been advocating the need of a robust scheme in all projects that I do. Often clients are reluctant to accept it. People believe it is uneconomical to attend to accidental loads! Not the case if we have a robust scheme. What is a robust scheme? Will seismically designed building be robust enough? Sometimes yes. Then what it is to be robust? Bridging of loads or alternate load path! How do you achieve it? Here is a short video on Disproportionate collapse basic principles. If you need more learning on this topic, wait for our blog. Join our mail list for receiving it (if you are already in mail list no need to rejoin). Join the forum by creating a login.
Can we ignore Accidental Collapse control? content media
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premjit

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