Railway
Design of bridges
Syllabus
• IRC Code • Types of bridges and their components • Basic concepts of bridge design • Design of slab bridge • Design of T-beam bridge (Courbon’s method)
IRC Code
• IRC – Indian Roads Congress • Three categories of Live loads • Types of vehicles • Placement of vehicles • Description of three category loadings • Permissible stresses and design coeff.
Categories of Live loads as per IRC
a.
IRC Class AA loading
i. For bridges subjected to very heavy loading ii. Used only in certain specified areas and municipal limits iii.Bridges designed for classAA loading should be checked for class A loading also
b.
IRC Class A loading
i. For permanent bridges and culverts
c.
IRC Class B loading
i. For temporary structures ii. Used only in specific areas
Types of vehicles
a. b.
c.
Tracked vehicles Wheeled vehicles Trains of vehicles
Placement of vehicles
a. b.
c.
d.
e.
f.
Extent: Within the kerb to kerb width of the roadway. NOT on the footpath, etc Orientation: travelling along the bridge. NOT across the bridge Multiple vehicles: with minimum clearance between vehicles. NOT touching each other Position: Any possible position which produces max. stresses. Standard vehicle: All the axles shall be acting simultaneously and at the prescribed distances No other live load shall be assumed on the carriage way besides the IRC loading
Class AA loading
Class AA loading (contd.)
a.
b.
c.
The nose to tail spacing between two successive vehicles shall not be less than 90 m. fig For multilane bridges and culverts, only ONE train of Class AA (tracked or wheeled vehicles) shall be considered for every two traffic lane widths. No other live load on the 2-lane width The maximum loads of the wheeled vehicles shall be 20 tonnes for a single axle, or 40 tonnes for a bogie of two axles spaced not more than 1.2 m centres.
Minimum clearance between the road face of the kerb and the outer edge
Syllabus
• IRC Code • Types of bridges and their components • Basic concepts of bridge design • Design of slab bridge • Design of T-beam bridge (Courbon’s method)
IRC Code
• IRC – Indian Roads Congress • Three categories of Live loads • Types of vehicles • Placement of vehicles • Description of three category loadings • Permissible stresses and design coeff.
Categories of Live loads as per IRC
a.
IRC Class AA loading
i. For bridges subjected to very heavy loading ii. Used only in certain specified areas and municipal limits iii.Bridges designed for classAA loading should be checked for class A loading also
b.
IRC Class A loading
i. For permanent bridges and culverts
c.
IRC Class B loading
i. For temporary structures ii. Used only in specific areas
Types of vehicles
a. b.
c.
Tracked vehicles Wheeled vehicles Trains of vehicles
Placement of vehicles
a. b.
c.
d.
e.
f.
Extent: Within the kerb to kerb width of the roadway. NOT on the footpath, etc Orientation: travelling along the bridge. NOT across the bridge Multiple vehicles: with minimum clearance between vehicles. NOT touching each other Position: Any possible position which produces max. stresses. Standard vehicle: All the axles shall be acting simultaneously and at the prescribed distances No other live load shall be assumed on the carriage way besides the IRC loading
Class AA loading
Class AA loading (contd.)
a.
b.
c.
The nose to tail spacing between two successive vehicles shall not be less than 90 m. fig For multilane bridges and culverts, only ONE train of Class AA (tracked or wheeled vehicles) shall be considered for every two traffic lane widths. No other live load on the 2-lane width The maximum loads of the wheeled vehicles shall be 20 tonnes for a single axle, or 40 tonnes for a bogie of two axles spaced not more than 1.2 m centres.
Minimum clearance between the road face of the kerb and the outer edge