Week 11 Challenge

Aim: To apply the temperature load on staad model of the bridge and analyze.

Given Data:

• The Span of the bridge is 9 m.
• The Box girder dimension is 1500 x 1500 with a web thickness of 300mm.
• The diameter of the circular pier is 2.5m
• The width of the Deck slab is 7m and the width of the pier cap is 6m.
• The Thickness of the Deck slab is 550mm.
• Section of pier cap-1100 x 1100 mm.
• Material of bridge-M40 concrete.(Fck =40)
• Location of the bridge - Delhi

Solution:

As per IRC 6, Annexure F, the Maximum and minimum temperatures at Delhi are 48.4 & -2.2 degrees celcius.

As the difference between maximum & minimum temperature is more than 20 degree celcius,

Effective temperature differnece = (48.4-(-2.2))/2 + 10=25.3 + 10 =35.3 degree celcius

Thermal expansion coefficient for concrete= 11.27 x 10^(-6)

Modulus of Elasticity of Concrete = 5000 x sqrt(40)

Stress due to Temprature = α x △T x E = 11.27 x 10^(-6) x 35.3 x 5000 x sqrt(40) =12.58 kN/m2

Maximum Permissible stress = (2/3) x Modulus of rupture of concrete =(2/3)* 0.7 * sqrt(40) =2.95 kN/m2

So it will be ensured that the stress to be encountered in the bridge deck shall not exceed 2.95 kN/m2.

Temperature to be applied in Staad pro as a load case:

The temperature at the Top =48.4 degree

The temperature at the Bottom =(2.1/17.8)*48.4 =5.71 degree (The ratio is taken from IRC 6,Figure 16A)

Temperature difference from top to bottom = 48.4 -5.71 =42.69 degree.

Modeling & Analysis in Staad Pro.

As per the given data, Staad model is prepared as shown below.

Properties were assigned as per the given data.

The temperature load has been assigned to the deck as shown below.

Analysis Results:

Piers:

The maximum Bending moment observed is 741.139 kN.m.

Pier CAP:

The maximum Bending moment observed is 871.964 kN.m

Box Girder:

The maximum Bending moment observed is 429.456 kN.m

Deck slab:

The maximum Bending moment observed is 260 kN.m