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UmarMakhzumi reacted to EngrUzair in Masonry Design Guidelines
In general, yes.
However, be careful to check other requirements (especially minimum sizes & reinforcement of confining members, with reference to wall density) for confined masonry design, as given in the document referred in para 1-b of my previous post, and the following guideline (more recent):
http://www.world-housing.net/wp-content/uploads/2011/08/ConfinedMasonryDesignGuide82011.pdf
Regards.
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UmarMakhzumi reacted to EngrUzair in Masonry Design Guidelines
Junaid,
1. If you go through the following threads, you will find several good references on the subject:
a. http://www.sepakistan.com/topic/1652-load-bearing-structure-design/?hl=masonry#entry4141
b. http://www.sepakistan.com/topic/1326-seismic-design-guide-for-masonry-buildings/?hl=masonry
c. http://www.sepakistan.com/topic/1313-modulus-of-elasticity-of-brick-masonary/?hl=masonry#entry2495
d. http://www.sepakistan.com/topic/1680-the-seismic-performance-of-rcc-frame-buildings-with-masonry-infill-walls/?hl=masonry
2. In case of a 3-story house, it would be better to use a framed or confined masonry structure, if the structure would be constructed in a location of seismic zone 2 or higher. Moreover, you would be requiring RC walls too, for the basement portion.
Regards.
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UmarMakhzumi reacted to Zain Saeed in Load Bearing Structure
I believe the attached document would give you a little guidance to overall manual design process in load bearing residential homes
Manual Design of Residential Homes.pdf
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UmarMakhzumi reacted to Nustian371 in confined masonry!!!
I am not sure if i picked up your question, but normally the confining reinforcement at the ends of confined masonry is to transfer the loads in tension compression. The Confined masonry in an earthquake act as compression strut and there are equations and guidance in FEMA to work out the capacities of these diagonal strut members. We do these checks very commonly here in New Zealand for the seismic analysis of the existing confined masonry structures. I would recommend you to have a read of the document i am attaching. Its called C8 and its part of the documentation used for the detailed seismic analysis of structures here in New Zealand.
Section_C8-Unreinforced_Masonry_Buildings.pdf
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UmarMakhzumi reacted to EngrUzair in Algo Centre Mall Demolition
Assalam-o-alaikum!
Here is the case of a civil engineering building, located in Canada, that had to be demolished, after developing structural problems soon after completion of construction. Worth reading by civil, and particularly structural engineers:
http://en.wikipedia.org/wiki/Algo_Centre_Mall
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UmarMakhzumi reacted to Ayesha in Structure Reinforcement Detailing
Post processing is unique to each office based on best practices. Normally each office has in-house excel sheets to do post processing. A lot also has to do with what kind of softwares are available.
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UmarMakhzumi reacted to Muhammad Hashmi in Importing ETABS file from v19.1 to v18.1
Assalam O Alykum
EDB file of version 19 is now opened in 2018. The below identified by the external consultant
Dear Hashimi;
I think I have found the problem, maybe It can be the configuration of decimals in your computer. I have the decimals as “,”. Maybe you have the configuration with “.”.
We have had sometimes problems due to the different configurations in our computers.
attach the .e2k file exported in a computer with the configuration “.” of the decimals.
Tell me if you can export it fine.
Kind regards.
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UmarMakhzumi got a reaction from Muhammad Hashmi in Response spectrum
Wsalaam Hashmi,
The way I read it is that if you have already included the effects in your analysis. I believe ETABS has an option to apply Seismic force at eccentricity. I am a bit rusty on this.
Thanks.
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UmarMakhzumi got a reaction from Muhammad Hashmi in Scale factor response spectrum
W.salaam Hashmi,
For the check 2, your base shear is different and so is deflection. What is the basis of this check?
Thanks.
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UmarMakhzumi got a reaction from Bijay karki in stiffness matrix from mode shape
My pleasure Ayman. One way to solve this would be to measure force causing this ambient vibrations using strain gauges that measure strain in structural members that can be convert back to force .. This will involve some assumptions and simplifications as well.
Thanks.
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UmarMakhzumi reacted to Badar (BAZ) in ETABS - Identify which walls have cracks
Yes, its enough to figure out if the tensile stresses in RC walls are exceeding the capacity of concrete to take tension, which means there will be cracks if it does that.
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UmarMakhzumi got a reaction from Sameer Khan in Stiffness Modifier
@Sohaib Iqbal,
You need to compare this number with modulus of rupture.
@baz, thanks for the refresher.
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UmarMakhzumi reacted to Badar (BAZ) in Beams
There is no beam-slab connection approach in ETABS. It can include the stiffness of flange automatically if you have defined a shell element for representing your slab, but it will calculate the required flexural rebars based on the cross-section defined for the line (beam) element.
Define a T-section if you want include the effect of flange for positive-moment capacity. In that case, you need to model the slab carefully; area element with shell property can result in over-estimation of stiffness if stiffness modifiers are not applied appropriately.
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UmarMakhzumi got a reaction from abbaskhan2294 in Construction Joint Detailing
Dear Abbas,
Probably because short side means less construction works especially for sawed-joints. I would suggest checking out ACI 224 as it is the go to document for constructions joints for more info. Hope that helps.
https://www.concrete.org/store/productdetail.aspx?ItemID=224395&Format=DOWNLOAD&Language=English&Units=US_AND_METRIC
Thanks.
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UmarMakhzumi got a reaction from Hamza Irshad in Construction Joint Detailing
Dear Abbas,
Probably because short side means less construction works especially for sawed-joints. I would suggest checking out ACI 224 as it is the go to document for constructions joints for more info. Hope that helps.
https://www.concrete.org/store/productdetail.aspx?ItemID=224395&Format=DOWNLOAD&Language=English&Units=US_AND_METRIC
Thanks.
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UmarMakhzumi got a reaction from Hamza Irshad in Construction Joint Detailing
Hamza,
To size, find the moment and shear at the section where the two rafts meet and ensure you have 1) enough flexural rebar 2) enough ties or shear capacity (Chapter 17 ACI 318-14) for shear limit states.
Thanks.
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UmarMakhzumi reacted to Wajahat Latif in Dual System Modeled as Sway/Non-Sway?
I agree with your observations. The 'sway moment' is amplified by P-Delta considerations, whether the frame is sway or non-sway and whether the column is slender or not. Regarding your following statement:
I think the non-sway factor (catering for deformations between the member ends, i.e., P_smallDelta effects) would be computed in both non-sway and sway cases. No? In non-sway frames, only non-sway factor needs to be applied. However, since we're doing a P-Delta analysis, the sway factor is also inherently present. Similarly, in sway cases, both sway and non-sway factors need to be applied. So, in essence, ETabs is applying both sway and non-sway factors for all kinds of framing.
As you've pointed out in the post you shared, as per code the moment magnification should not be applied for short columns, i.e., they can be designed on first order moments. However, given the above discussion, it seems these amplifications are being applied regardless if the column is short or slender.
Now, I just noticed that the non-sway moment factor in "Concrete Frame Design Overwrites" is by default set as 1. We would need to set it to 0 for the program to compute this itself for each member for each load combination (screenshot attached). I suppose if we're confident that our columns are non-slender, then we can avoid the non-sway factor by keeping this as 1. The sway factor would still be applied via P-Delta.
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UmarMakhzumi reacted to Badar (BAZ) in Dual System Modeled as Sway/Non-Sway?
I have also pointed out this observation in this attached post.
I have looked at its manual. Here is what I found, and which also addresses why the ETABS magnifies moments even if you set column as non-sway.
ETABS split design forces in columns as M= Ms + (sway factor for amplification of forces)Mns; the component Ms is from lateral loads and Mns is from gravity loads only.
Sway factor is taken as 1, as the program "assumes" that Ms comes from the P-delta analysis. If P-delta analysis is performed, the moment magnification is already incorporated in that, and there is no need to amplify moments. So sway factor is taken as 1.
Once M has been calculated, the program amplifies it further by using a non-sway factor, see the attached.
So, if you have used non-sway option, then this non-sway factor will be 1. But, since you have performed the P-delta analysis for drift related checks, your forces have already been amplified.
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UmarMakhzumi reacted to Wajahat Latif in Dual System Modeled as Sway/Non-Sway?
Thanks. I agree with your points. I was running into a problem with a couple of columns in a dual system building. Based on the ACI 318-19 criteria of slenderness effects (Section 6.2.5), these columns are classified as slender in a sway frame but non-slender in a non-sway frame (based on the different slenderness limits for sway and non-sway frames in this section). When they're behaving slender, the ACI check mentioned in Section 6.2.5.3 (i.e, second order moments < 1.4 * first order moments, screenshot attached) should be applied. For my case, these columns are failing this check. However, I know from manual calculation that this is a non-sway frame and the columns are infact non-slender, therefore, this check can be ignored.
In ETabs 19, this check is applied whether the framing type is sway or non-sway (columns fail this check in both cases). This makes me wonder, does ETabs perform all slender column checks and calculations regardless of whether the column is slender or not? Any idea how ETabs checks column slenderness?
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UmarMakhzumi reacted to Badar (BAZ) in Dual System Modeled as Sway/Non-Sway?
Yes, they will be ignored.
But why do you want to select the non sway option? Your design moments will not be effected much by the moment magnification factors and P-delta analysis if l/r ratio of columns is small, and if lateral drifts are also with in the limits.
If you are enabling the P-delta analysis option, program will magnify your column moments anyway based on the results of P-delta iterations even if non-sway option has been selected (sway part of moment magnification equation of ACI 318 is still there because of lateral loads).
One should not rely on the seismic checks performed by ETABs. Unless you have specified the actual reinforcement ( the ones in structural drawings) to the program, these results are useless.
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UmarMakhzumi got a reaction from Muhammad Hashmi in Long term deflection
W/Salaam,
Yes, I think so.
Thanks.
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UmarMakhzumi reacted to Badar (BAZ) in Modelling Steel Truss with Overhang on ETABS
Check your supports. What type of supports have you assigned? Have you assigned any end releases?
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UmarMakhzumi got a reaction from Kamranullah in Flexural cracks in beams
You can measure the deflection by using a thread and putting it across the floor and then seeing if floor is lower than the thread. Anyway, if the reinforcement works, that's fine. If it doesn't you should retrofit the beam.
Thanks.