05-13-2009, 04:47 AM
@ Column Design
As far as I'm experienced in using ETABS, it is true that ETABS only gives column steel reinforcement if option of reinforcement to be design was selected. How it calculates steel area without having arrangement of steel ? I had implement a program which is similar to PCACOL and the way it design the reinforcement is quite different than PCACOL whereas the PCACOL use steel area arrangement in design. The way it design is using a lot of steel area arrangement (i.e 100 steel bars, So it is more like a steel strip in the concrete), but the diameter of bars is a variable needs to be found according to the axial and moment load. After the diameter is found then the area of steel reinforcement could be found by multiplying the area with sum of the total bar (100) and it only says that it requires xxxx mm2 of reinforcement not the number of steel reinforcement with its area (i.e 4-D25). I think the ETABS had done the same way, it could be using a lot of reinforcement or using a steel strip.
Since ETABS didn't show any value in interaction curve so it will be more difficult in seeing whether the load is satisfied or there could be error in the interaction curve (Based on experience) I would prefer PCACOL or CSICOL in designing concrete columns as a cross check in ETABS design.
@ Beam Design
How do we know which the distance required ? By checking the inflection point of the moment. For example the simple ways is if the moments in the support is negative we should check the location where the moments is began to change into positive it is the point where the steel area requirement in the support should stop theoritically, but since the steel reinforcement in the support and midspan should connect each other, the location of the inflection point should be extended according to the development length required (Usually 40 db is satisfied). By this way the continuity of steel reinforcement in beams is satisfied.
@ Composite Beam and Column
I had never design this type of element in ETABS, I think using manual calculation or other RC design component such as CSICOL will be more wise. For this case ETABS just for analysis.
CMIIW,
regards
piscesa
As far as I'm experienced in using ETABS, it is true that ETABS only gives column steel reinforcement if option of reinforcement to be design was selected. How it calculates steel area without having arrangement of steel ? I had implement a program which is similar to PCACOL and the way it design the reinforcement is quite different than PCACOL whereas the PCACOL use steel area arrangement in design. The way it design is using a lot of steel area arrangement (i.e 100 steel bars, So it is more like a steel strip in the concrete), but the diameter of bars is a variable needs to be found according to the axial and moment load. After the diameter is found then the area of steel reinforcement could be found by multiplying the area with sum of the total bar (100) and it only says that it requires xxxx mm2 of reinforcement not the number of steel reinforcement with its area (i.e 4-D25). I think the ETABS had done the same way, it could be using a lot of reinforcement or using a steel strip.
Since ETABS didn't show any value in interaction curve so it will be more difficult in seeing whether the load is satisfied or there could be error in the interaction curve (Based on experience) I would prefer PCACOL or CSICOL in designing concrete columns as a cross check in ETABS design.
@ Beam Design
How do we know which the distance required ? By checking the inflection point of the moment. For example the simple ways is if the moments in the support is negative we should check the location where the moments is began to change into positive it is the point where the steel area requirement in the support should stop theoritically, but since the steel reinforcement in the support and midspan should connect each other, the location of the inflection point should be extended according to the development length required (Usually 40 db is satisfied). By this way the continuity of steel reinforcement in beams is satisfied.
@ Composite Beam and Column
I had never design this type of element in ETABS, I think using manual calculation or other RC design component such as CSICOL will be more wise. For this case ETABS just for analysis.
CMIIW,
regards
piscesa