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BivekSigdel SEFI Member
Joined: 12 Jul 2016 Posts: 8

Posted: Thu Aug 15, 2019 2:21 am Post subject: P and V values to be taken while defining auto hinge for pushover analysis in etabs, sap2000 


Dear all,
I've searched a lot, but still couldn't get an idea what is the appropriate loading case or combination to get the values of P and V while defining auto hinge for pushover analysis in etabs or sap2000. P and V values are required as per the table 107, 108 of ASCE 4113, table 67, 68 of FEMA 356 and table 113, 114 of ATC 40.
For each column the P value can be maximum due to different load combinations. So does it mean that I have to know which combination gives max. P in each column and assign different auto hinge for each column? Also the case/combination for maximum value of V can be different from P. In this case how can we assign only one load case/combination for both P and V values.
For beams, maximum V values result from the ductility requirements due to sway and hinge formation in beams and not from load cases/combinations.
I would really be grateful if somebody could give me an insight to which load case/combination is appropriate of P and V values while defining auto hinge for pushover analysis in etabs or sap2000.
Please see the picture attached.
Thankyou,
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rojanmathewtsy General Sponsor
Joined: 21 Apr 2013 Posts: 26

Posted: Fri Aug 16, 2019 6:50 am Post subject: Re: P and V values to be taken while defining auto hinge for pushover analysis in etabs, sap2000 


BivekSigdel wrote:  Dear all,
I've searched a lot, but still couldn't get an idea what is the appropriate loading case or combination to get the values of P and V while defining auto hinge for pushover analysis in etabs or sap2000. P and V values are required as per the table 107, 108 of ASCE 4113, table 67, 68 of FEMA 356 and table 113, 114 of ATC 40.
For each column the P value can be maximum due to different load combinations. So does it mean that I have to know which combination gives max. P in each column and assign different auto hinge for each column? Also the case/combination for maximum value of V can be different from P. In this case how can we assign only one load case/combination for both P and V values.
For beams, maximum V values result from the ductility requirements due to sway and hinge formation in beams and not from load cases/combinations.
I would really be grateful if somebody could give me an insight to which load case/combination is appropriate of P and V values while defining auto hinge for pushover analysis in etabs or sap2000.
Please see the picture attached.
Thankyou, 
Regarding your query on the P value,
M3 hinge(Momentcurveture relationship) will be varying depending on the axiall load acting on the cross section. Since the axial load varies on different load case, your M3 curve will also vary depending on the load case.
So basically you will be doing pushover after the end of one specific load case that you will be mentioning while defining the pushover load case(in the initial stiffness condition box) . So here , you have to mention that load case that you used to define the pushover.
So if you are planning to check pushover with respect to different load cases, then you may have to make different models to check that.
Regarding V value also, you can follow the same load case. You can manually input the shear reinforcement ratio as your shear design is governed by ductile requirement.
Note Columns will be governed by PMM hinges as it will be having combined action of axial load and bi axial moments.
Rojan Mathew
mathew.rojan@gmail.com


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BivekSigdel SEFI Member
Joined: 12 Jul 2016 Posts: 8

Posted: Sun Aug 18, 2019 3:15 am Post subject: Re: P and V values to be taken while defining auto hinge for pushover analysis in etabs, sap2000 


[quote="rojanmathewtsy"]
"So here , you have to mention that load case that you used to define the pushover. "
Thankyou for your response,
Suppose for initial stiffness I create a load case i.e NLDEAD
Then following the NLDEAD load case I define Load cases PushX and PushY.
Now for P and V values do you mean I should take the values from NLDEAD or PushX and PushY ?


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rojanmathewtsy General Sponsor
Joined: 21 Apr 2013 Posts: 26

Posted: Tue Aug 20, 2019 4:25 am Post subject: Re: P and V values to be taken while defining auto hinge for pushover analysis in etabs, sap2000 


[quote="BivekSigdel"] rojanmathewtsy wrote: 
"So here , you have to mention that load case that you used to define the pushover. "
Thankyou for your response,
Suppose for initial stiffness I create a load case i.e NLDEAD
Then following the NLDEAD load case I define Load cases PushX and PushY.
Now for P and V values do you mean I should take the values from NLDEAD or PushX and PushY ? 
If you are doing push x and Push Y , then you have to consider two models, Model 1 for push X where P and V value will be of Push X and Model 2 with push Y.
But I will recommend you to go for manual hinges that you can define using section designer.
1.For Columns
Define PMM hinges  that will not be load case dependit will be constant for a section. So you dont have to make different Models.
Define Shear Hinges also Shear hinge will be also depend on your section property only.
2. For Beams
Define M2 or M3 hinges Here the Moment hinges will be constant with respect to the cross section as axial load P is Zero or negligible in beams.
Define Shear hinges also.
Rojan Mathew
mathew.rojan@gmail.com


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BivekSigdel SEFI Member
Joined: 12 Jul 2016 Posts: 8

Posted: Fri Aug 23, 2019 1:17 am Post subject: Re: P and V values to be taken while defining auto hinge for pushover analysis in etabs, sap2000 


[quote="rojanmathewtsy"] BivekSigdel wrote:  rojanmathewtsy wrote: 
"So here , you have to mention that load case that you used to define the pushover. "
Thankyou for your response,
Suppose for initial stiffness I create a load case i.e NLDEAD
Then following the NLDEAD load case I define Load cases PushX and PushY.
Now for P and V values do you mean I should take the values from NLDEAD or PushX and PushY ? 
If you are doing push x and Push Y , then you have to consider two models, Model 1 for push X where P and V value will be of Push X and Model 2 with push Y.
But I will recommend you to go for manual hinges that you can define using section designer.
1.For Columns
Define PMM hinges  that will not be load case dependit will be constant for a section. So you dont have to make different Models.
Define Shear Hinges also Shear hinge will be also depend on your section property only.
2. For Beams
Define M2 or M3 hinges Here the Moment hinges will be constant with respect to the cross section as axial load P is Zero or negligible in beams.
Define Shear hinges also.
Rojan Mathew
mathew.rojan@gmail.com 
Thankyou Mr. Rojan, however since Pushx and PushY are two seperate load cases, SAP or ETABS can seperately analyse both cases. So is it still necessary to work on two seperate models?


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