06-09-2010, 04:09 PM
iceman84 wrote:-
...You can provide beams with dimensions greater than that of the columns if you have shear walls which provide the necessary lateral strength....
Comment:-
I do not think that this provision was made with respect to provision of lateral stability as such, the case of shear wall does not come in. If you are contrary to this please give me a reference to this provision.
,,,,you can increase the reinforcement (and the dimensions) of the column until it's ok,...
Comment:-
This is a verge statement. Please indicate on how you will know when it is ok (what calculations do you have to accomplish)
,,,,But, you must take into consideration the fact that the building will not fail if a plastic hinge forms in a column, rather than in a beam (it is necessary to have plastic hinges in all the columns). Further more the plastic hinges must form in all the columns both at the top part and at the bottom part,,...
Comment:-
I beg to disagree with that statement. If not, why is it that the code (EUROCODE) requires that the hinges be formed in the beams rather than in the column, This will amount to suicide if the hinges are to be formed in the columns rather than in the beams (like you are suggesting). This will result in brittle collapse which will be fatal as there will be no pre-failure warning
.....So, in my opinion the best solution is to provide an adequate amount of reinforcement in the column and detail it accordingly, but keeping in mind the fact that a plastic hinge is very likely to form there (the rest of the columns must be detailed according to capacity design rules).....
Comment:- how much is adequate as to comply with this requirement?
tamboon wrote:-
.....in design you can take beam stiffness 50% of its full stiffness while still maintaining column stiffness to 100% of its full stiffness or :
Beam, I design = 50% I gross beam
Column, I design = 100% I gross beam
ACI uses :
Beam, I design = 35% I gross beam
Column, I design = 70% I gross column.....
Comment:-
Like was pointed out by Grunf, colud you please cite these clause or how you arrived at the figures that you quoted?
Regards
Teddy
...You can provide beams with dimensions greater than that of the columns if you have shear walls which provide the necessary lateral strength....
Comment:-
I do not think that this provision was made with respect to provision of lateral stability as such, the case of shear wall does not come in. If you are contrary to this please give me a reference to this provision.
,,,,you can increase the reinforcement (and the dimensions) of the column until it's ok,...
Comment:-
This is a verge statement. Please indicate on how you will know when it is ok (what calculations do you have to accomplish)
,,,,But, you must take into consideration the fact that the building will not fail if a plastic hinge forms in a column, rather than in a beam (it is necessary to have plastic hinges in all the columns). Further more the plastic hinges must form in all the columns both at the top part and at the bottom part,,...
Comment:-
I beg to disagree with that statement. If not, why is it that the code (EUROCODE) requires that the hinges be formed in the beams rather than in the column, This will amount to suicide if the hinges are to be formed in the columns rather than in the beams (like you are suggesting). This will result in brittle collapse which will be fatal as there will be no pre-failure warning
.....So, in my opinion the best solution is to provide an adequate amount of reinforcement in the column and detail it accordingly, but keeping in mind the fact that a plastic hinge is very likely to form there (the rest of the columns must be detailed according to capacity design rules).....
Comment:- how much is adequate as to comply with this requirement?
tamboon wrote:-
.....in design you can take beam stiffness 50% of its full stiffness while still maintaining column stiffness to 100% of its full stiffness or :
Beam, I design = 50% I gross beam
Column, I design = 100% I gross beam
ACI uses :
Beam, I design = 35% I gross beam
Column, I design = 70% I gross column.....
Comment:-
Like was pointed out by Grunf, colud you please cite these clause or how you arrived at the figures that you quoted?
Regards
Teddy