CHAPTER 6: STRUCTURAL ANAYLSIS
6.1 MODELLING
6.1.6 DESIGN FORCES
Figure 49 Shear force Diagram for Beams.
The figure 49 exhibits the shear forces attained after analysing the structure. A similar observation is made in beams shear force. The edge beams have lesser shear force values in comparison to middle beams. The analysis of the slabs was overlooked as observed the statistical analysis that the deterioration is less in slabs compared to beams and columns.
Table 57: Design forces Corner Column C1
243.2459 484.974 728.7652 969.935 1216.5134 1484.1618 1731.5744 1969.7505
244.6368 487.2569 731.7748 974.1618 1221.01 1488.5031 1735.4853 1974.0196
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
CONER COLUMN AXIAL FORCE COMPARISION
Deteriorated Model Non Deteriorated Model
Figure 50 Corner Column Axial Forces Comparison
Figure 51 Corner Column Moment Comparison
The Table 57 exhibits the design forces for the two models made for the corner column. It has been observed from the figure 50 that there is not much significant difference in the axial forces.
Whereas from the figure 51 its can be observed that there is a significant difference in the moments acquired. in most cases the deteriorated model has lower moment in comparison to the non-deteriorated model.
5.4469 3.1889 3.9911 4.1449 0.06 3.948 1.6546 1.3785
5.0002 3.7073 4.0779 4.1704 0.3826 3.2186 2.0052 2.33
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
CORNER COLUMN MOMENT COMPARISION
Deteriorated Model Non deteriorated Model
Table 58 Design forces Intermediate Column C69
The table 58 exhibits the design forces for the two models made for the intermediate column.
It has been observed that there is a difference in the design force values. On calculating the difference, it was observed that it is lesser than 1% in axial forces and no difference in the shear force values thereby considered insignificant. For design purposes the value higher amongst the two have been considered for evaluation of columns in the intermediate location.
Figure 52 Intermediate Column Axial Forces Comparison
Figure 53 Intermediate Column Moment Comparison
The figure 52 shows the comparative axial forces for the deteriorated and non-deteriorated model. It can be observed that there is no significant difference in the axial forces of both the models. Although figure 53 helps to understand that there is a difference in moment where
268.2827 569.7427 871.5109 1172.5166 1474.3394 1777.0379 2063.8121 2323.1049
267.9784 568.0482 868.6101 1169.1231 1469.9688 1771.6794 2057.811 2315.4503
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
INTERMEDIATE COLUMNS AXIAL FORCE COMPARISION
Deteriorated Model Non Deteriorated Model
34.6255 18.2626 29.9143 23.2289 28.0016 6.2454 4.4649 2.6902
29.9594 22.1645 26.5261 22.6153 28.1569 5.5047 3.3257 2.2391
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
INTERMEDIATE COLUMNS MOMENT COMPARISION
Deteriorated Model Non Deteriorated Model
in which the moments in the deteriorated model are more with respect to non-deteriorated model.
Table 59 Design forces Middle Column C82
The Table 59 exhibits the design forces for the two models made for the middle column. It has been observed that there is a difference in the design force values, although very minor and can
be considered negligible for axial forces. For design purposes the value higher amongst the two have been considered for evaluation of columns in the intermediate location.
Figure 54 Middle Column Axial Forces Comparison
Figure 55 Middle Column Moment Comparison
228.9642 454.5762 680.3534 905.6692 1130.2144 1352.4348 1635.3114 1931.0928
229.6625 455.609 680.8136 905.9574 1130.8479 1353.3518 1633.8579 1927.0046
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
MIDDLE COLUMN AXIAL COMPARISION
Deteriorated Model Non Deteriorated Model
9.3291 4.886 11.1001 8.8606 10.0281 20.8544 50.8097 13.1485
7.8276 6.39 10.7755 9.4083 10.6623 20.7194 48.8051 11.5726
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
MIDDLE COLUMN MOMENT COMPARISION
Deteriorated Model Non Deteriorated Model
The figure 54 exhibits the axial forces for the two models made for the middle column. It has been observed that there is a difference in the design force values, although very minor and can be considered negligible for axial forces. Similarly, there is a very minor difference in the design moment values which is exhibited in the figure 55. As there is a very minor difference it can be neglected as it does not have a major impact on the design.
6.1.6.2 BEAMS
This part of the study exhibits the design forces acquired from the two Etabs model for deteriorated and non-deteriorated structure. The study focussed on comparing the design forces for the two different categories of beam namely the edge beam and the middle beam for the highest design force values.
Table 60 Design forces Edge Beam 343
The table 60 exhibits the design forces for edge beam. It is observed that there is very little difference in the design forces amongst the two models.
Figure 56 Shear force Comparison Edge Beam
The figure 56 exhibits the design shear forces for edge beam. It is observed that there is a minor difference between the two models. The percentage of difference in with 1% and hence can be neglected.
Figure 57 Positive Moment Comparison Edge Beam
30.0158 30.702 29.0368 35.3051 29.3826 28.6295 24.9074 24.347930.325 31.596 29.8696 35.6358 30.6119 30.0604 26.0456 24.9417
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
SHEAR FORCE EDGE BEAM COMPARISION
Deteriorated Model Non Deteriorated Model
17.5303 17.6253 16.6037 21.8447 16.5397 16.036 12.7451 12.2517.1381 17.3364 16.0845 21.0142 16.565 16.2582 12.1311 11.5835
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
+VE MOMENT COMPARISON EDGE BEAM (BOT STEEL)
Deteriorated Model Non Deteriorated Model
Figure 58 Negative Moment Comparison Edge Beam
The figure 57 & 58 exhibits the design moment values used to design the beam for bottom and top reinforcement respectively. It is observed that there is a marginal difference in between the two models generated. The difference is so small that it can be neglected. Although it is observed that the non-deteriorated model has a higher moment values whereas the deteriorated model has a slightly higher shear force design values.
Table 61: Design forces Middle Beam 169
20.0505 20.9552 19.6683 26.8294 18.7551 18.5716 15.8364 16.561919.5371 21.4096 19.7914 25.793 19.3667 20.6501 16.7151 14.925
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
-VE MOMENT COMPARISION EDGE BEAM (TOP STEEL)
Deteriorated Model Non Deteriorated Model
The table 61 exhibits the design forces for middle beam. It is observed that there is very little difference in the design forces amongst the two models. Although in comparison to the edge beams the variations in the middle beams are more.
Figure 59 Shear force Comparison Middle Beam
The figure 59 exhibits the design shear forces for middle beam. it is observed that the shear force values for the non-deteriorated model is more in comparison to the deteriorated model, although the difference is very small and can be deemed insignificant.
Figure 60 Positive Moment Comparison Middle Beam
73.7245 71.8842 67.9312 68.1101 67.1708 65.6175 53.626 68.669
74.2711 73.2743 71.7451 71.1307 69.4145 68.5736 56.03 72.8765
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
SHEAR FORCE MIDDLE BEAM COMPARISION
Deteriorated Model Non Deteriorated Model
26.4952 26.9548 25.9718 26.3847 26.2484 25.6993 25.0361 27.3798
26.7238 27.8915 27.6624 27.5935 27.4325 27.2035 27.1617 29.4843
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
+VE MOMENT COMPARISON MIDDLE BEAM (BOT STEEL)
Deteriorated Model Non Deteriorated Model
Figure 61 Negative Moment Comparison Middle Beam
The figure 60 & 61 exhibits the design moment values used to design the beam for bottom and top reinforcement respectively. Figure 65 shows slight variations of a difference of 2 Kn/m2. This difference is not much significant in terms of having a major impact in design changes.
Further for the negative moment seen in figure 66 the difference is quite marginal and can be considered insignificant to have an impact on design. In this study we can understand that with the change in material properties there is a small difference in the design forces, although the difference is very small and has no significant impact in the design of the structural elements and thus the difference found in the forces can be considered negligible.
40.7286 37.0237 32.0013 31.6167 27.1891 26.4655 19.8964 21.7361
40.9464 37.6644 33.5805 32.6135 27.9409 27.0347 21.8378 23.5979
S I X T H F I F T H F O U R T H T H I R D S E C O N D F I R S T M E Z Z G R O U N D
-VE MOMENT COMPARISION MIDDLE BEAM (TOP STEEL)
Deteriorated Model Non Deteriorated Model
(A.) Max. Story Displacement Deteriorated Model (B.) Max Story Displacement Normal Model
Figure 62 Maximum Story Displacement Comparison
The figure 62 exhibits the comparative view of story displacement for the deteriorated model and non-deteriorated model. The max story displacement has no significant difference due to the change in property parameters. Although the figure 67 exhibits that the drift for non- deteriorated model is lesser than the deteriorated model. Thus exhibiting a small difference in drift values due to change in property parameters while modelling. A smaller drift indicates a better rigidity for the structure.
(A.) Max. Story Drift for Deteriorated Model (B.) Max Story Drift for Normal Model Figure 63 Maximum Story Drift Comparison