| Structural Engineers' eBook Seismic Analysis+Design of RC Buildings |
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RCC slabs, beams and columns of a multi-storeyed building are analyzed and designed for gravity and seismic loads by the stiffness method. Reinforcement in slabs, beams and columns is calculated per various codes of practice. User input is greatly simplified as there is no need to number elements and nodes or to specify member connectivity and section properties. Uniform loads on slabs are automatically converted to trapezoidal or triangular loads on beams. To begin with, a blank form named NEW is shown. You have the option to select any other input file from the drop-down list at the top of the page. After filling out the forms as described below, or even after filling part of relatively large input, you may save the data in a file of your choice. Entire input is entered in one web page consisting of three forms shown below. The first form captures number of storeys and their heights, material properties and seismic data. High yield strength deformed bars are used by default. OMRF stands for Ordinary Moment Resisting Frame and SMRF stands for Special Moment Resisting Frame. SMRF's are detailed for ductile behaviour whereas OMRF's are not. Most frequently used values are preassigned to second and third
columns of this form for your convenience. You may change them as
required. Effective concrete cover is to be entered in the
second column.
Details of various element types viz. column, beam and slab are entered in the next form shown below.
An element mark has at least two characters : the first character represents element type C, B or S followed by an alpha or numeric element identifier. Thus CA, B11 and Sa are all valid examples of element marks. Entries in the form are more or less self-explanatory. Cx and Cy are the dimensions of column parallel to x (horizontal) and y (vertical) axes, bw and D are beam width and overall depth respectively and t is overall slab thickness. Enter unfactored uniform loads on beams and slabs exclusive of self weight. Note that the framing plan accepts a single slab/beam mark which applies to typical level. It is likely that loading and size of slabs and beams at ground and roof levels will be different from those on typical level. Such elements can be specified in the form above by appending G or R to the slab/beam mark on typical floor. Orientation of columns is important. Thus, a column with dimensions 300 mm and 500 mm along x and y axis is of different type as compared to a column with dimensions 500 mm and 300 mm along x and y axis respectively. The last form defines floor layout. Far left column and bottom row are used for entering distances between grid-lines in millimeters. Cells marked C, B and S represent columns, beams and slabs respectively. Choose appropriate identifier in each cell from those entered in the next form partially shown below: Depending on the floor layout, some cells may not have any column, beam or slab. Leave such cells as they are. It is possible to cater for variation of column types along height. Let us say that, for a six storeyed building, lower four columns at a grid location are of type C1 and the upper three columns are of type C2 (Note that pedestal from foundation to plinth level and one in each of the six storeys make up 7 columns). The entry for this situation would be 4C1/3C2. Alternatively, this could also be entered as 4C1/C2. The software assigns column type C2 to the uppermost three storeys. If there is no variation of column types along height, then you may just enter that single column type designation, say C5. In practice, pedestals from footing to ground level are slightly larger in size as compared to the ground storey column due to increased concrete cover. As the increased cover is ineffective in resisting moments, it is safer to specify pedestal of same type as the ground strorey column. Let us take an example of a two storeyed single bay building, in seismic zone 3 shown below.
The data for this example is entered as follows: And here is the resulting output:
Moments (kN-m/m) Steel (sq.mm/m)
Slab Type Mx1 Mxm Mx2 My1 Mym My2 Asx1 Asxm Asx2 Asy1 Asym Asy2
-------------------------------------------------------------------------------------------
A1B2 S1 -ve 0.0 0.0 0.0 0.0 Top <180 <180 <180 <180
+ve 21.0 21.0 Bot 494 494
A1B2 S1R -ve 0.0 0.0 0.0 0.0 Top <180 <180 <180 <180
+ve 16.8 16.8 Bot 388 388
Beam Type Shear Moment Stirrups Longitudinal Steel
Ends kN kN-m sv/asv(/mm) (sq. mm)
1 2 End1 End2 End1 Middle End2 End1 End2 End1 Middle End2
--------------------------------------------------------------------------------------------
A1 A2 B1 84.37 84.38 -36.81 88.19 -36.81 >3.46 >3.46 Top <277 <277
Bot 553
B1 B2 B1 84.38 84.37 -36.81 88.19 -36.81 >3.46 >3.46 Top <277 <277
Bot 553
A1 B1 B1 84.37 84.38 -36.81 88.19 -36.81 >3.46 >3.46 Top <277 <277
Bot 553
A2 B2 B1 84.38 84.37 -36.81 88.19 -36.81 >3.46 >3.46 Top <277 <277
Bot 553
A1 A2 B1G 34.69 34.69 -23.37 19.99 -23.37 >3.46 >3.46 Top <215 <215
Bot <215
B1 B2 B1G 34.69 34.69 -23.37 19.99 -23.37 >3.46 >3.46 Top <215 <215
Bot <215
A1 B1 B1G 34.69 34.69 -23.37 19.99 -23.37 >3.46 >3.46 Top <215 <215
Bot <215
A2 B2 B1G 34.69 34.69 -23.37 19.99 -23.37 >3.46 >3.46 Top <215 <215
Bot <215
A1 A2 B1R 60.00 60.00 -17.25 73.37 -17.25 >3.46 >3.46 Top <277 <277
Bot 459
B1 B2 B1R 60.00 60.00 -17.25 73.37 -17.25 >3.46 >3.46 Top <277 <277
Bot 459
A1 B1 B1R 60.00 60.00 -17.25 73.37 -17.25 >3.46 >3.46 Top <277 <277
Bot 459
A2 B2 B1R 60.00 60.00 -17.25 73.37 -17.25 >3.46 >3.46 Top <277 <277
Bot 459
Column Type Case Axial Mx My Vx Vy As svx/Asvx svy/Asvy
kN kN-m kN-m kN kN sq.mm per mm per mm
-----------------------------------------------------------------------------------------
3A1 C1 DL 130.12 17.25 17.25 5.75 5.75 <720
DL+Ex 109.94 13.80 28.40 13.67 4.60 <720 >3.46
DL+Ey 109.94 28.40 13.80 4.60 13.67 <720 >3.46
2A1 C1 DL 309.00 18.40 18.40 12.27 12.27 <720
DL+Ex 270.13 14.72 44.85 28.37 9.82 1080 >3.46
DL+Ey 270.13 44.85 14.72 9.82 28.37 1080 >3.46
1A1 C1 DL 383.44 23.37 23.37 15.58 15.58 <720
DL+Ex 342.69 18.69 40.94 31.96 12.46 962 >3.46
DL+Ey 342.69 40.94 18.69 12.46 31.96 962 >3.46
3A2 C1 DL 130.13 17.25 17.25 5.75 5.75 <720
DL+Ex 109.94 13.80 28.40 13.67 4.60 <720 >3.46
DL+Ey 109.94 28.40 13.80 4.60 13.67 <720 >3.46
2A2 C1 DL 309.00 18.40 18.40 12.27 12.27 <720
DL+Ex 270.13 14.72 44.85 28.37 9.82 1080 >3.46
DL+Ey 270.13 44.85 14.72 9.82 28.37 1080 >3.46
1A2 C1 DL 383.44 23.37 23.37 15.58 15.58 <720
DL+Ex 342.69 18.69 40.94 31.96 12.46 962 >3.46
DL+Ey 342.69 40.94 18.69 12.46 31.96 962 >3.46
3B1 C1 DL 130.13 17.25 17.25 5.75 5.75 <720
DL+Ex 109.94 13.80 28.40 13.67 4.60 <720 >3.46
DL+Ey 109.94 28.40 13.80 4.60 13.67 <720 >3.46
2B1 C1 DL 309.00 18.40 18.40 12.27 12.27 <720
DL+Ex 270.13 14.72 44.85 28.37 9.82 1080 >3.46
DL+Ey 270.13 44.85 14.72 9.82 28.37 1080 >3.46
1B1 C1 DL 383.44 23.37 23.37 15.58 15.58 <720
DL+Ex 342.69 18.69 40.94 31.96 12.46 962 >3.46
DL+Ey 342.69 40.94 18.69 12.46 31.96 962 >3.46
3B2 C1 DL 130.12 17.25 17.25 5.75 5.75 <720
DL+Ex 109.94 13.80 28.40 13.67 4.60 <720 >3.46
DL+Ey 109.94 28.40 13.80 4.60 13.67 <720 >3.46
2B2 C1 DL 309.00 18.40 18.40 12.27 12.27 <720
DL+Ex 270.13 14.72 44.85 28.37 9.82 1080 >3.46
DL+Ey 270.13 44.85 14.72 9.82 28.37 1080 >3.46
1B2 C1 DL 383.44 23.37 23.37 15.58 15.58 <720
DL+Ex 342.69 18.69 40.94 31.96 12.46 962 >3.46
DL+Ey 342.69 40.94 18.69 12.46 31.96 962 >3.46
Actions Reinforcement
Column Case X-Frames Y-Frames X-Frames Y-Frames
Left Right Left Right Left Right Left Right
------------------------------------------------------------------------------------------
3A1 M(DL+E) kN-m 0.00 -28.40 0.00 -28.40 Top sq.mm <277 <277
Bot sq.mm
M(DL-E) kN-m 0.00 0.80 0.00 0.80 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m 0.00 -34.05 0.00 -34.05 Top sq.mm <277 <277
Bot sq.mm
M(D-E) kN-m 0.00 8.77 0.00 8.77 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 0.00 53.84 0.00 53.84 End /mm >3.46 >3.46
V(E) kN 0.00 7.30 0.00 7.30 Mid /mm >3.46 >3.46
2A1 M(DL+E) kN-m 0.00 -72.18 0.00 -72.18 Top sq.mm 465 465
Bot sq.mm
M(DL-E) kN-m 0.00 13.28 0.00 13.28 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m 0.00 -79.00 0.00 -79.00 Top sq.mm 513 513
Bot sq.mm
M(D-E) kN-m 0.00 38.06 0.00 38.06 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 0.00 84.59 0.00 84.59 End /mm >3.46 >3.46
V(E) kN 0.00 21.37 0.00 21.37 Mid /mm >3.46 >3.46
3A2 M(DL+E) kN-m -28.40 0.00 0.00 -28.40 Top sq.mm <277 <277
Bot sq.mm
M(DL-E) kN-m 0.80 0.00 0.00 0.80 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m -34.05 0.00 0.00 -34.05 Top sq.mm <277 <277
Bot sq.mm
M(D-E) kN-m 8.77 0.00 0.00 8.77 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 73.34 0.00 0.00 53.84 End /mm >3.46 >3.46
V(E) kN 7.30 0.00 0.00 7.30 Mid /mm >3.46 >3.46
2A2 M(DL+E) kN-m -72.18 0.00 0.00 -72.18 Top sq.mm 465 465
Bot sq.mm
M(DL-E) kN-m 13.28 0.00 0.00 13.28 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m -79.00 0.00 0.00 -79.00 Top sq.mm 513 513
Bot sq.mm
M(D-E) kN-m 38.06 0.00 0.00 38.06 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 84.59 0.00 0.00 84.59 End /mm >3.46 >3.46
V(E) kN 21.37 0.00 0.00 21.37 Mid /mm >3.46 >3.46
3B1 M(DL+E) kN-m 0.00 -28.40 -28.40 0.00 Top sq.mm <277 <277
Bot sq.mm
M(DL-E) kN-m 0.00 0.80 0.80 0.00 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m 0.00 -34.05 -34.05 0.00 Top sq.mm <277 <277
Bot sq.mm
M(D-E) kN-m 0.00 8.77 8.77 0.00 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 0.00 53.84 53.84 0.00 End /mm >3.46 >3.46
Actions Reinforcement
Column Case X-Frames Y-Frames X-Frames Y-Frames
Left Right Left Right Left Right Left Right
------------------------------------------------------------------------------------------
V(E) kN 0.00 7.30 7.30 0.00 Mid /mm >3.46 >3.46
2B1 M(DL+E) kN-m 0.00 -72.18 -72.18 0.00 Top sq.mm 465 465
Bot sq.mm
M(DL-E) kN-m 0.00 13.28 13.28 0.00 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m 0.00 -79.00 -79.00 0.00 Top sq.mm 513 513
Bot sq.mm
M(D-E) kN-m 0.00 38.06 38.06 0.00 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 0.00 84.59 84.59 0.00 End /mm >3.46 >3.46
V(E) kN 0.00 21.37 21.37 0.00 Mid /mm >3.46 >3.46
3B2 M(DL+E) kN-m -28.40 0.00 -28.40 0.00 Top sq.mm <277 <277
Bot sq.mm
M(DL-E) kN-m 0.80 0.00 0.80 0.00 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m -34.05 0.00 -34.05 0.00 Top sq.mm <277 <277
Bot sq.mm
M(D-E) kN-m 8.77 0.00 8.77 0.00 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 73.34 0.00 53.84 0.00 End /mm >3.46 >3.46
V(E) kN 7.30 0.00 7.30 0.00 Mid /mm >3.46 >3.46
2B2 M(DL+E) kN-m -72.18 0.00 -72.18 0.00 Top sq.mm 465 465
Bot sq.mm
M(DL-E) kN-m 13.28 0.00 13.28 0.00 Top sq.mm
Bot sq.mm <277 <277
M(D+E) kN-m -79.00 0.00 -79.00 0.00 Top sq.mm 513 513
Bot sq.mm
M(D-E) kN-m 38.06 0.00 38.06 0.00 Top sq.mm
Bot sq.mm <277 <277
V(DL+E) kN 84.59 0.00 84.59 0.00 End /mm >3.46 >3.46
V(E) kN 21.37 0.00 21.37 0.00 Mid /mm >3.46 >3.46
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