Week 4 Challenge
Aim and Introduction:-
- The aim of this challenge is to determine the types of loads and forces acting on the abutment structure and to design with determining the detail reinforcement drawing for the abutment structure.
- So first of all the details components, levels with sizes specified from the given GAD.
- For designing IRC 6 & IRC 112 has been reffered.
Design
- Basic Design Data
- Partial Safety Factor
- Load data
- Load Calculation from Super Structure
- Earth Pressure Co-ifficient
- Live Load Calculation
- Foces Due to earth Pressure
- Forces on abutmentr and foundation
- Check for over turning
- Check for sliding
- Check for Base Pressure
- Design of Open Foundation for both the combination and different load cases
- Moment Of resistance
- Design
- Considering Combination 1
- Design of Heel Slab
- Design of toe slab
- SLS (Comb 2)
-
1 Max pressure at toe (Corner 1) and corresponding pressure at heel 2 Min pressure at heel (Corner3 ) and corresponding pressure at toe Corner Gross Pressure Corner Gross Pressure t/m2 t/m2 1 23.1 1 22.9 2 15.7 2 16.1 3 10.2 3 9.9 4 17.6 4 16.8
| SERVICIBILITY LIMIT STATE, ULS (COMB 2) | ||||||||||||
| Using interpolation of triangles, the pressure at face of the support & at 'd' distance from the support is determined. | ||||||||||||
| Heel End | 15.8+10.2/2 | 13.0 | t/m2 | |||||||||
| Gross | Toe End | (23.2+17.6)/2 | 20.3 | t/m2 | ||||||||
| A-A | 13+(4.8/7.5)*(20.4-13) | 17.7 | t/m2 | |||||||||
| B-B | 13+((7.5-1.7)/7.5)*(20.4-13) | 18.7 | t/m2 | |||||||||
| At deff from A-A | 17.7-912.5/1000/4.8*(17.7-13) | 16.8 | t/m2 | |||||||||
| At deff from B-B | 20.4-912.5/1000/1.7*(20.4-18.7) | 19.4 | t/m2 | |||||||||
| Heel End | 13-(2*(7.71-0.3)-2.5*0.3)*1.35 | -6.0 | t/m2 | |||||||||
| Toe End | 20.4-(2.5*0.3+2*(226.58-224.58))*1.35 | 13.9 | t/m2 | |||||||||
| Net | A-A | 17.7-(2*(7.71-1)-2.5*1)*1.35 | 2.9 | t/m2 | ||||||||
| B-B | 18.7-(2.5*1)*1.35 | 15.3 | t/m2 | |||||||||
| At deff from A-A | 16.78-(2*(7.71-866.9/1000)-2.5*866.9/1000)*1.35 | 1.2 | t/m2 | |||||||||
| At deff from B-B | 19.5-(2.5*624.3/1000)*1.35 | 17.3 | t/m2 | |||||||||
| Similarly for case 2, the gross & net pressure values are calculated. | ||||||||||||
| Pressure (t/m2) | Section | |||||||||||
| Heel End | A-A | Toe End | B-B | At deff from A-A | At deff from B-B | |||||||
| Gross Pressure (Case 1) |
13.0 | 17.7 | 20.3 | 18.7 | 16.8 | 19.4 | ||||||
| Gross Pressure (Case 2) |
13.0 | 17.4 | 19.8 | 18.3 | 16.6 | 19.0 | ||||||
| Net Pressure (Case 1) | -6.0 | 2.9 | 13.9 | 15.3 | 1.2 | 17.3 | ||||||
| Net Pressure (Case 2) | -5.9 | 2.7 | 13.4 | 14.9 | 1.0 | 16.9 | ||||||
| Modular Ratio | m | = | 6.25 | |||||||||
| Permissible stress in concrete | = | 0.48*fck | = | 16.8 | Mpa | |||||||
| = | 0.8*fyk | = | 400 | Mpa | ||||||||
| Side | Face | Moment | deff | Ast.provided | Neutral axis depth | Stress in concrete |
Stress in steel | Check | ||||
| t-m | mm | mm2/m | mm | MPa | MPa | |||||||
| Heel | Top | -117.2 | 912.5 | 4908.7 | 207.92 | 13.37 | 283.17 | OK | ||||
| Bottom | -117.84 | 912.5 | 4908.7 | 207.92 | 13.44 | 284.70 | OK | |||||
| Toe | Bottom | 51.6 | 912.5 | 4908.7 | 207.92 | 5.88 | 124.58 | OK | ||||
Detailing
- The detailing for the abutment drawing has been generated in autocad.
- The detail of the drawing has been shown separatedly as below.
SECTION A-A
3.The diffrerence between flyover and river bridge is, a flyover is a structure in which the road is crossing an obstruction other than stream, river or any water bodies and ion case of river bridge the road is passing over a stream.
- In case of river over bridge there will be additional effect of water current, if the river is used as navigational channel then impact load of water vehicles need to be considered.
- But in in flyover there is no water forces on the structure.
- There is difficult in constructing structure in side a river because generally due to presence of water in the stream through out the year. And generally in the river bridge deep foundation need to be provided. So there will be constructinal difficulty due to water. First of all the flow/stream needs to be controlled before constructing. but there is no such cases in flyover. Rather for flyover open foundation may be provided.
- In case of river bridge there will be effect of scouring in structure which is need to be taken in designing and in flyover there is no such case also will occur as there is no flow of water.