Structural requirements PORTAL METHOD OF APPROXIMATE ANALYSIS. Now a day, shear wall in R.C.structure and steel bracings in steel structure are most popular system to resist lateral load due to earthquake, wind, blast etc. Can this type of brick bond be used for bearing walls? Below , copy and paste of some paragraphs of EC -8 EN 1998-1:2004 related with this topic; "since post tensioned slabs don't crack during service loads". The positive value of the axial force indicates tension. Sign Up to The Constructor to ask questions, answer questions, write articles, and connect with other people. Cloud Computing in Construction: Are we Availing all its Benefits?
Pile foundations usually find resistance to lateral loads from (a) passive soil resistance on the face of the cap, (b) shear on the base of the cap, and (c) passive soil resistance against the pile shafts.
The fact that the end deflection is smaller is due to the effective uplift from PT, not due to increased slab stiffness. Approximate Lateral Load Analysis by Portal Method, Compaction and Roller Requirement for Embankment and Subgrade, CHARACTERISTICS OF A CONSTRUCTION PROJECT, Understanding the Transfer of Loads from Slab to Beams. The resulting forces must check with the free body diagram at the opposite end. VIP members get additional benefits. Most lateral loads vary in intensity depending on the building's geographic location, structural materials, height and shape. I am familiar with EC -8 bu i did not think till i read this thread. This white paper shows how collaborative robots can play a role in helping companies succeed in the Covid-19 world: to help with social distancing, ramp up new lines quickly and reshore existing products due to interrupted supply chains.
I amn't convinced with this statement as the contribution of the slab stiffness for lateral load resistance might demand special detailing.
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Eurocode 8 states two things, a) - slab frame action should not be considered as a lateral resisting system and b) - any element can be called a secondary seismic element as long as the total stiffness hasn't changed by more than 15% when you remove all the secondary elements. Country
That floor plan is designed to create cracking, whether it is prestressed or not. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Concrete tensioning does not really stiffen the slabs - it just changes the behaviour of the concrete section through introduction of an axial component. Some features of the site may not work correctly.
There is this argument around where I work which goes ' since post tensioned slabs don't crack during service loads, slab stiffness for lateral load computation can go as high as 0.5(eurocode, although it doesn't say for slabs) times the gross stiffness'. Firstly, keep in mind that it is interstory drift, rather than absolute drift, that will matter the most in this. There is this argument around where I work which goes ' since post tensioned slabs don't crack during service loads, slab stiffness for lateral load computation can go as high as 0.5(eurocode, although it doesn't say for slabs) times the gross stiffness'.
Please enter your email address. Is there any approximate method to analyse lateral uniformly distributed loads?
We obtain the shear in each column from a free body diagram of the structure above the hinge level by assigning shear to the interior column equal to twice the shear in exterior column as shown in Fig. The shears are shown without any sign. Provide enough deformed bar reinforcement to limit cracking to an acceptable level. The knowledge of: If a larger load comes, it'll crack a section, when it reduces back to quasipermanent, those cracks will close.
The resulting forces are indicated on the diagram.
The maximum values of shear and axial forces are indicated along each member.
Yeah, in EN 1998-1 4.3.1 (7) "Unless a more accurate analysis of the cracked elements is performed, the elastic flexural and shear stiffness properties of concrete and masonry elements may be taken to be equal to one-half of the corresponding stiffness of the uncracked elements.". Along with gravity load structure has to withstand to lateral load which can develop high stresses. The shear wall is one of the best lateral load resisting systems which is widely used in construction world but use of steel bracing will be the viable solution…, Seismic Response of R C Building With Different Arrangement of Steel Bracing System, Effect of shear wall in high-rise building subjected to dynamic loading, SEISMIC PERFORMANCE OF R C BUILDINGS ON SLOPING GROUNDS WITH DIFFERENT TYPES OF BRACING SYSTEMS, Seismic Evaluation of High-rise Structure by Using Steel Bracing System, A Research on Comparing the Seismic Effect on Shear wall building and Without- Shear Wall Building – A Review, Earthquakes Analysis of High Rise Buildings with Shear Walls at the Center Core and Center of Each Side of the External Perimeter with Opening, Seismic Behaviour of RCC Framed Structure with Different Bracing System, A COMPARATIVE STUDY ON SEISMIC PERFORMANCE EVALUATION OF IRREGULAR BUILDINGS WITH MOMENT RESISTING FRAMES AND DUAL SYSTEMS, Analysis of Moment Resisting Frame by Knee Bracing, Seismic Behavior Of RC Building Frame With Steel Bracing System Using Various Arrangements, Effectiveness of Changing Reinforced Concrete Shear Wall Location on Multi-storeyed Building, EFFECT OF CHANGE IN SHEAR WALL LOCATION ON STOREY DRIFT OF MULTISTOREY BUILDING SUBJECTED TO LATERAL LOADS, Lateral load pattern in pushover analysis, Solution of Shear Wall Location in MultiStorey Building, Effect of Height on Seismic Response of Reinforced Cement Concrete Framed Buildings with Curtailed Shear Wall, Seismic performance of RC frames with concentric internal steel bracing, Cyclic Tests on the Internally Braced RC Frames, SEISMIC BEHAVIOUR FACTOR, R, FOR STEEL X-BRACED AND KNEE-BRACED RC BUILDINGS, EFFECT OF INTERNAL AND EXTERNAL SHEAR WALL LOCATION ON STRENGTHENING WEAK RC FRAMES, By clicking accept or continuing to use the site, you agree to the terms outlined in our. 2.
That's what informed my post.
The basis for the third assumption stems from the reasoning that the frame is composed of individual portals as shown in Fig.3. 7. I think that it should not, but you know your structure better. what if one of the column is missing in the given frame? The only question remains will this reduce any stiffness? For RC slabs a value close to zero is usually used and am okay with that. The following example illustrates the procedure involved in the analysis of building frames by the portal frame method.
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Again inflection points are assumed at mid-height of lower storey columns and the shear is distributed as in the upper storey. Already a Member? You could almost say that the slab is "effectively" stiffer, but not really.
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Approximate Lateral Load Analysis by Portal Method Portal Frame Portal frames, used in several Civil Engineering structures like buildings, factories, bridges have the primary purpose of transferring horizontal loads applied at their tops to their foundations.
Hardbutmild thanks, I am supposed to design the slab and so its upto me to recommend the stiffness modifiers for the lateral load resisting system designing guys and they say the modifier used for slabs is affecting the system critically . What are Load Factors and Strength Reduction Factors in Concrete ... Matrimandir: Construction Features of a Unique Temple, Calculate Quantities of Materials for Concrete -Cement, Sand, Aggregates, Methods of Rainwater Harvesting [PDF]: Components, Transport, and Storage.
The portal method is an approximate analysis used for analyzing building frames subjected to lateral loading such as the one shown in Fig.1.
In order to satisfy damage limitation requirement of EC number of shear walls around the perimeter of the building has been placed and it is the designers belief that this shear walls would limit the expected drift of the building well below certain limit that the column slab junction wouldn't be expected to transfer large amount of moment, hence resolving punching issues during design or frequent seismic event. You are currently offline. What I suggested was to use 15% and you have already mentioned in your post why 15% is my number and I got it from Michael N. Fardis book on seismic design based on EC.yet they demand more from PT slabs than what is suggested for RC once. This method is more appropriate for low rise buildings with uniform framing. You will receive a link and will create a new password via email.
Tips to Avoid Reinforcement and Embedment Congestion in Concrete Members, Thumb Rules and Specifications for Design of Reinforced Concrete Beam. An inflection point is located at the centre of each beam, Fig.
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Lost your password? At each step of the successive approximations lateral loads are first distributed among vertical structural elements. What is the reinforced concrete deep beam and where it used?
Now a day, shear wall in R.C.structure and steel bracings in steel structure are most popular system to resist lateral load due to earthquake, wind, blast etc. Typical lateral loads would be a wind load against a facade, an earthquake, the earth pressure against a beach front retaining wall or the earth pressure against a basement wall. 2. you are completely right; even properly designed PT members may experience hairline cracking in service because the PT is only ever meant to zero-out the self-weight. Click Here to join Eng-Tips and talk with other members! Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. So it's either full stiffness or some slightly reduced value in reality. I can't figure it out. Once the design lateral loads are known on the two-dimensional frames, one could analyze the frame for the member forces. In this paper, a new lateral load pattern is presented to enhance the accuracy of conventional pushover analysis (CPA) procedures for evaluating seismic behaviors of asymmetric-plan multistory buildings, which has considered the effect of torsion and higher modes.
Does the bending stiffness of your slab influence the lateral stiffness by more than 15%?
Approximate Lateral Load Analysis by Portal Method Home / Structural Engineering / Structural Analysis / Analysis of Frames The portal method is an approximate analysis used for analyzing building frames subjected to lateral loading such as the one shown in Fig.1.