Why upper floor columns require more rebar than lower floor?
Top story columns have lesser axial force and moment from beams higher than bottom floors (as explained above). So they are subjected to higher tensile forces. An increase in moment demands more steel than an increase in compression. Hence Top story columns demand more steel than a bottom story.
Why sometimes upper floor column requires more reinforcement than bottom floor in FEM analysis?
Rebar requirement in the columns of topmost storey can be more than that required in the storey below. Generally column longitudinal reinforcement are design for the combined action of moment and axial load. At lower floors axial load will be maximum but moments may not maximum.
How do you reduce column reinforcement?
How do I reduce the size of a column in construction:-column with same axial capacity and strength of load bearing structure/vertical support, in construction civil engineering, i can reduce size/cross-section of column by implementation of 3 methods, 1) you should provide higher grade of concrete with higher …
Can we reduce column size for upper floors?
It is possible to reduce the column size in the upper floors. But it may be economical to have same column sizes every 4 floors. It is because, as though column loads reduce in the upper columns proportionately. Column moments will increase, resulting in more reinforcements if you reduce the column size.
How do you do column reduction?
Row Reduction
- Perform elementary row operations to yield a “1” in the first row, first column.
- Create zeros in all the rows of the first column except the first row by adding the first row times a constant to each other row.
- Perform elementary row operations to yield a “1” in the second row, second column.
What is the standard size of column for 2 storey house?
Column size for 2 storey (G+1) building:- For this general thumb rule, we will assume a structure of G+1 (2 storey) residential building, using standard 5″ walls, size of an RCC column should be 9”x 12” (230mm x 300mm) with 6 bars of 12mm Fe500 Steel with m20 grade of concrete and stirrups of T8@6″C/C.
What are the 3 types of columns?
The three major classical orders are Doric, Ionic, and Corinthian. The orders describe the form and decoration of Greek and later Roman columns, and continue to be widely used in architecture today.
What is FC column?
Floating Column or Hanging Columns. The floating column is a vertical member which rest on a beam but doesn’t transfer the load directly to the foundation. The floating column acts as a point load on the beam and this beam transfers the load to the columns below it.
Which mm bar is used in a column of a 3 story building?
According to general thumb rule, we will assume a structure of G+2/3 storey/three floor residential building, using standard 9″ thick walls, the best mm bar used for 3 storey/G+2 building, we should use steel bar of 12mm dia for footing, combination of 12mm & 16mm dia of steel bar used for column, 12mm dia of steel bar …
How to reduce the cost of construction with ETABS?
You should always check the design moments that ETABS uses for columns if you want to bring down the cost of construction. If your model has lateral loads, ETABS will give you design moments in column irrespective of its status as braced or un-braced as per ACI 318 criteria.
Does ETABS provide design moments for un-braced columns?
If your model has lateral loads, ETABS will give you design moments in column irrespective of its status as braced or un-braced as per ACI 318 criteria. You should investigate if the storey under consideration is braced, or un-braced (10.10.5.2), and decide appropriate design moments of columns.
What should one check when using ETABS?
One should always check the time period used by the software; ETABS can overestimate the seismic force by more than 2 times. Method A gives lower T and higher V, so FEMA 451 has advised not to use the value of time period less than this value even if rigorous analysis gives a lower value.
Can ETABS calculate seismic force from time period other than ta?
So, there is no need to use the value of time period that is lot less than Ta. One should always check the time period used by the software; ETABS can overestimate the seismic force by more than 2 times. More sharing options… ILYAS, even ETABS 9 had the similar options but that did not work.