INTERNATIONAL JOURNAL OF CIVIL AND STRUCTURAL ENGINEERING Volume 1, No 3, 2010
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Loads on the top of slab
Total load for bending moment and shear force is considered from IRS code rules specifying the loads for designing the superstructure and substructure of bridges and for assessing the strength of existing bridges. For span of 8m total load for bending moment
981kN and total load for shear force is 1154kN is considered. Dead load of earth fill over the box = Area x depth x density
Total vertical pressure on top slab = Imposed load + Dead load + Live load
2.2 Loads on sidewalls
The coefficient of active earth pressure of the soil is given by the equation
1 c o s
c o s
c o s
γ = Density of soil, ф = Angle of internal friction, = angle of friction between wall and earth fill Where value of is not determined by actual tests, the following values may be assumed.
for concrete structures. for masonry structures.
i = Angle which the earth surface makes with the horizontal behind the earth retaining structure ( i =00 for embedded structure). Since this concrete structure is embedded in soil, the value of is considered as 1/3 (for concrete structures) considered for calculation of coefficient of active earth pressure
of the soil.
Earth pressure acting on the sidewalls:
a) Earth pressure due to backfill
Earth pressure center of top slab = Earth pressure center of bottom slab = Ka H Ka H
2.3. b) Earth pressure due to dead load surcharge
Earth pressure acting on sidewalls: At Top = Imposed load of track + Earth pressure on the top of slab + Live load
AT Bottom = Horizontal effect of surcharge + Earth pressure center of bottom slab 1.7