Week 12 Challenge

Aim: To calculate the barge impact load of the Panamax vessel to be applied on the bridge as shown in the question and do the analysis in Staad pro.

Given data:

The Deadweight tonnage of the Panamax vessel (W) is 52500 DWT

The speed of the Barge (V) is 60Km/hr or 16.67 m/s

The span of the Bridge is 12m Width of the bridge is 7m. Supported by Piers of size 2.5 m x 2.5m. The Rise of the bridge is 5m. The Deck slab is 500mm thick. The cross Girders are 0.75 m x 1.8 m in dimensions.

Hydrodynamic coefficient (Ch) as 1.25

Assumed data:

Section considered for Main Girder = 0.75 m x 1.8 m

Section considered for Verticals= 0.5 m x 0.5 m

Other Members of the truss =0.4 m x0.4 m

C/c distance between the cross girders = 3 m

Solution:

Barge Collision Energy = KE = 500 x Ch x W x V^2

= 500 x 1.25 x 52500 x 16.67 ^2 =8899392022.5 N .m

Barge Impact Depth,

aB= 3100 x ( [1 + 1.3 x 10(-7) x KE]^0.5 - 1)

=102387 mm

Which is more than 100 mm,

So Barge Collision Impact Force (PB) = 6.0 x 10^6 + 1600 x (aB) = 169819200 N =169819 kN

Modeling In Staad Pro.

By considering the assumed and given data, staad model is prepared.

The properties of the different members are assigned accordingly.

The calculated barge load is then applied horizontally,

Results & Discussion:

Deck:

Maximum Bending Moment observed = 935 kN.m

Pier:

Maximum Bending moment = 29268 kN.m