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i have some questions and i am hoping to find some answers from you kind people.
1) when we use doubly reinforced beams how can be obtain economy be controlling ceiling height ?
2) where do we use bar curtailment and bent up bars in beams because there are not ACI provisions related to bar curtailment (as far as i know)
3)i have seen examples in books they calculate steel area for beams and they provide combination of different dia bars to satisfy that area why they do it because they can satisfy same area using same dia bars ?
4)which design method Etabs uses. LRFD or ASD?
5) how do we design the hanger bars. what is ACI provision for it?
6)where do we use inclined stirrups in beams ?
7) how the longitudinal reinforcing can be used as shear reinforcement ?
Thank you all in advance. Looking forward to your responses.
My assignment was to construct a design response spectrum using Newmark and Hall method for 5% damping for a given peak acceleration 0.25g.The question stated that the peak velocity of 122 cm/sec,peak displacement of 91 cm are consistent with a peak acceleration of 1g. Related to that I had to plot the design response spectrum for 0.25 g.Can you explain,what is meant by consistent?we have been given a formula to to find out peak velocity and displacement in relation to the consistency with 1g but what is it actually?
I solved the tripartite graph from the formula given and I plotted the pseudovelocity design spectrum from which at different time instance where after amplification and at time instance 1/33,1/8,10 and 33 sec ,I was able to plot acceleration vs time graph by equation as (A=xTy where,A=acceleration,T=time,x and y comes from solving two equation as example when T=0.02,A=1g,T=0.5,A=5g,from which x and y values were determined).I wonder why are we using this empirical formula.
The Spectrum obtained by Newmark and Hall method was then compared with IS 1893 -2000 fig .2 (for hard rock) and was compared.When we plotted the above mentioned acceleration ie 0.25g we didnot know the site condition so maybe ,the plot was different to IS 1893-2002? Noted that the IS 1893 -2000 was for 1g ,we scaled it to 0.25g and was compared.(Please refer to Clause.6.4.2 from IS 1893-2002 and the excel sheet attached herewith )
During this whole process,I don't know why we used a consistent acceleration(as mentioned above) to get a plot for 0.25g? and when we compared it with IS 1893-2000 .Does this means that the consistent acceleration we compared were the available data from previous earthquakes?or is it just empirical assumption?
I would be very glad to have insights on the doubt I am actually having.Thankyou
I have a phase/wall/column issue. Existing architectural columns (column wraps) that are intersected by New Construction walls appear....
In the New construction drawings I have a wall that merges with the column wrap.......
That might have caused some inconsistencies in the calculations (very small/large values) and could have caused this error. There is not much diff in behaviour if you change from 0.01 to 0.0001 so keep the previous value.
That would not solve the problem i reckon.
The biggest problem would be to control the excessive sway. The question you need to ask is if there would be any human occupancy in there/visiting deck etc? 99% chances are NO. There will be no human occupancy so limiting the sway & acceleration is out of the equation now. That leaves you with a sway limit of as high as 1/100 instead of usual 1/400 for buildings under service winds. You might need to pay attention to non structural components design for the drifts they gonna accommodate.