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Sandeepk SEFI Member
Joined: 03 Dec 2017 Posts: 1

Posted: Sun Dec 03, 2017 10:26 am Post subject: How to apply Vertical earthquake load in etabs 


How to apply vertical earthquake load in etabs as i am modeling building in zone IV and need to apply vertical earthquake load 

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sagar_shinde SEFI Member
Joined: 16 May 2013 Posts: 1

Posted: Mon Dec 04, 2017 5:28 am Post subject: Re: How to apply Vertical earthquake load in etabs 


Sandeepk wrote:  How to apply vertical earthquake load in etabs as i am modeling building in zone IV and need to apply vertical earthquake load 
You can apply static earthquake by defining EqZ. For dynamic analysis there is no such provision in ETABS. All you can do is Define Spec Z and give scale factor value maximum of Spec X and Spec Y. Although I would like to get expert opinion about this solution till ETABS is updated. 

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aditya ...
Joined: 05 Apr 2008 Posts: 158

Posted: Tue Jun 18, 2019 5:10 pm Post subject: 


Dear Sefians,
Shall we distribute the vertical seismic base shear V_{by}=A_{v}*W in each storey following the same formula as used for horizontal base shear as given in clause 7.6.3 (a) of IS 1893 Part 1: 2016? Please clarify since the code seems to be silent on this matter.
For example, vertical seismic force in storey i will be given by the following formula or not?
Q_{yi}=A_{v}*W_{i}*h_{i}^{2}/sum(W_{i}*h_{i}^{2}) where XZ is the horizontal plane and Y is the vertical direction, A_{v}=design vertical seismic coefficient=(2/3)*A_{h}
with regards,
Aditya 

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aditya ...
Joined: 05 Apr 2008 Posts: 158

Posted: Wed Jun 26, 2019 1:28 pm Post subject: 


Dear Er. S. Arun Kumar,
It seems nobody is interested or not using this clause. Can you help me on this topic related to how to apply vertical earthquake force at different floors in a multistoreyed RC Building? Thanks in advance.
with best regards,
Aditya 

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rahul.leslie General Sponsor
Joined: 01 Apr 2008 Posts: 492 Location: Trivandrum

Posted: Fri Jun 28, 2019 5:16 am Post subject: 


Find Av (6.4.6, IS:18932016) from
Av = (2/3)*(Z*I)/(2*R)*(2.5)
and define vertical earthquake EQv
EQv = Av*(DL+reduced.LL)
... use this EQv in place of 'ELz' in the combinations described in 6.3.4.1, IS:18932016 

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hemal ...
Joined: 01 Apr 2008 Posts: 129

Posted: Sun Jun 30, 2019 6:30 am Post subject: How to apply Vertical earthquake load in etabs 


(1) Vz = Av*W'
Av = 2/3 * Ahmax = 2/3 * Z/2 * I/R' *2.5
R'=R as per indian code. However other codes have specified between 1 to 1.5 in absence of exact value.
W''=W as per indian code. However according to other codes it includes only dead load or it is less than that for horizontal load.
Distribution of Vz along height of structure is similar to that for horizontal loads.
This approach requires to apply vertical seismic loads globally.
(2) Some other codes allows to consider its effect on partial model (or elements) which can get significal forces due to such actions. For higher seismic zones (IV & V), vertical seismic effects may be considered globally. Otherwise its effects shall be limited to large cantilevers (>5m), large span beams (>20m), prestressed elements, elemens (beam, columns, walls) supporting vertical elements having inplane or out of plane offset etc. When effects are considered on partial model or on element, Av shall be multiplied with seismic weight of element and shall be applied on element as vertical seismic load as separate load case and shall be combined with other loads as per codal requirement.
Some other codes likes ASCE have simplied procedure to consider vertical seismic effects. It requires to amplify dead load effects (BM, SF etc) by certain factor. Such factor as per indian code may be 0.3ZI. Load factor for dead load in all seismic load combinations shall be amplified by factor (1+0.3*Z*I) or (10.3*Z*I) to account for vertical seismic load effects.
Chinese code requires to consider verical seismic effect globally in higher seismic zones, and for lower and moderate seismic zones it requires to consider vertical seismic effect as 10% of representative gravity load (75% of total gravity load) for cantilever elements and 20% for large span elements.
Also, when vertical seismic loads are combined with horizontal seismic loads, no of load combinations can be reduced drastically to reduce design time by using the sign of verical seismic load action wisely.
e.g. 1.5D+1.5EQh+0.3(1.5EQv)
1.2D+1.2L+1.2EQh+0.3(1.2EQv)
0.9D+1.5EQh0.3(1.5EQv)
Hope this helps.
Hemal Mistry
Sent from Yahoo Mail on Android
Posted via Email 

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hemalmistry ...
Joined: 01 Jul 2009 Posts: 59

Posted: Thu Jul 04, 2019 7:30 am Post subject: How to apply Vertical earthquake load in etabs 


(1) Vz = Av*W'
Av = 2/3 * Ahmax = 2/3 * Z/2 * I/R' *2.5
R'=R as per indian code. However other codes have specified between 1 to 1.5 in absence of exact value.
W''=W as per indian code. However according to other codes it includes only dead load or it is less than that for horizontal load.
Distribution of Vz along height of structure is similar to that for horizontal loads.
This approach requires to apply vertical seismic loads globally.
(2) Some other codes allows to consider its effect on partial model (or elements) which can get significal forces due to such actions. For higher seismic zones (IV & V), vertical seismic effects may be considered globally. Otherwise its effects shall be limited to large cantilevers (>5m), large span beams (>20m), prestressed elements, elemens (beam, columns, walls) supporting vertical elements having inplane or out of plane offset etc. When effects are considered on partial model or on element, Av shall be multiplied with seismic weight of element and shall be applied on element as vertical seismic load as separate load case and shall be combined with other loads as per codal requirement.
Some other codes likes ASCE have simplied procedure to consider vertical seismic effects. It requires to amplify dead load effects (BM, SF etc) by certain factor. Such factor as per indian code may be 0.3ZI. Load factor for dead load in all seismic load combinations shall be amplified by factor (1+0.3*Z*I) or (10.3*Z*I) to account for vertical seismic load effects.
Chinese code requires to consider verical seismic effect globally in higher seismic zones, and for lower and moderate seismic zones it requires to consider vertical seismic effect as 10% of representative gravity load (75% of total gravity load) for cantilever elements and 20% for large span elements.
Also, when vertical seismic loads are combined with horizontal seismic loads, no of load combinations can be reduced drastically to reduce design time by using the sign of verical seismic load action wisely.
e.g. 1.5D+1.5EQh+0.3(1.5EQv)
1.2D+1.2L+1.2EQh+0.3(1.2EQv)
0.9D+1.5EQh0.3(1.5EQv)
Hope this helps.
Hemal Mistry
Posted via Email 

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