In RC Pier, is it possible to apply a load factor to the self weight of concrete (for cap self weight in particular)?
Hi ,
Yes, It is possible to apply a load factor to the self weight of concrete.
Self weight is generally a dead load case and the program considers DC load case to apply load factors to Self weight.
To Assign a different load factors to self weight .
1) Select DC load case and DO NOT generate the loads .This Load case will be assigned as DC1.
2) Select DC load case again and then generate requisite dead loads . This Load case will be assigned as DC2.
3) Generate other load case related to the project.
4) Now select the Load group , For example : Strength group 1 .
5) Click on Combinations button and in the new window click on Default Combination button.
6) Select Combinations which has DC1 load case and then click on EDIT button and you in the new window you should be able to change the load factors.
7) One more solution is to click on LIBRARIES option and Select "Load Groups/Limit State " option from the drop down menu.
8) In the new window you can click on ADD button and Customize the load group itself.
9) The drawback is that if you customize the load factor for DC load then same load factor will be applied to Self weight and other DC Dead loads.
It is not possible to change the load factors for pier cap alone as the load factors will be applied to entire self weight of the structure.
I have attached a Microsoft word file with the graphical representation of the procedure that needs to followed to assign customized load factors to Self weight.
Please let me know if you need any additional information.
Thanks & Regards,
Vinay
Answer Verified By: Vinay mysore
Thank you for your response.
This is a follow-up. I am trying to use RC-Pier to design a grade beam (2' ht x 3' width) between 30" dia drilled shaft piles. The piles are spaced 8' c-c with the grade beam spanning between. There is a 1.67' thick, 14 ft high wall on top of the grade beam. Design is to be done using LFD. No LL on wall, grade beam, or piles. Wall is a couple of hundred feet long so I'm only designing a portion of it for worst case.
I selected the "Cap Shape" of Inverted T but progam states that Inverted T cap is not supported by LFD code. Is there a way to model and design this grade beam?
I am looking to design the reinforcing in the grade beam. Reinforcing in the wall is done separately.
Thanks.
You are welcome.
There is no direction solution to your problem but I can suggest you a workaround solution for your issue.
If you don't have to design the wall and the drill shaft then please follow the below mentioned procedure.
"Just to let you know that it is not possible to model a drill shaft without assigning columns "
Please follow the suggestions mentioned below.
1) Open a new RCpier file . Select the code as LFD.
2) Select Abutment design --> Pile Cap Design --> Cap on continuous beam (now the pile cap will act like a continuous beam on piles).
3) In the Geometry TAB select the Abutment configuration option. input the WB and WD value as 0.01 and input SD and SW as per your requirement.
4) Go to Super structure button and input all the superstructure information.
5) Then click on footing option and in the new window change the diameter of the piles to 30" and change the pile/shaft length and then click on EDIT PILE option.
6) In the new window assign only required number of piles.
7) Input the bearings at the center of the beam.
8) Then go to Loads TAB and apply all the requisite loads and select the appropriate load groups.
9) Go to CAP TAB design the beam.
10) Go to Pile reaction TAB and get the pile reaction ( Program does not design the piles )
11) Click on the MODEL button and you should be able to see the moment diagram.
I have attached a word file which explains the procedure graphically.