02-07-2010, 04:08 PM
To answer refer to Post: #1: Shabas as follows:
I am familiar with designs relating with box culverts or underpass bridge, especially for highway and railway track.
Generally I did simple calculations with 2 dimensional frame and I assume spring as soil bearing at bottom of the box. The value of spring see table 9-1 "Range of values of Modulus of Subgrade Reaction ks" in Foundation Analysis and Design, Bowles, page 409.
About distribution width for live load: There are many books or design specification explaining about equivalent width for example in AASHTO LRFD Bridge for one lane of highway with 3600mm width, the equilvalent width may be determinded as E=2440+0.12 S. S=Clear Span.
The distribution reinforcement placed in the bottom of all slabs transverse to the main reinforcement and this amount of distributin may be determided by percentage of main reinf = 55/sqrt(L), L is clear span.
Other minor reinforcement is determined based on the allowable width of crack.
About earthquake loading is neglected, especially for box culvert.
I used to use SAP software to design the box frame. And I think all the structure softwares are as good as SAP. Now depends on the designer how to determine the soil spring parameter dimension, reinforcement arrangement and allowable deflection based on the code used in your country.
I am familiar with designs relating with box culverts or underpass bridge, especially for highway and railway track.
Generally I did simple calculations with 2 dimensional frame and I assume spring as soil bearing at bottom of the box. The value of spring see table 9-1 "Range of values of Modulus of Subgrade Reaction ks" in Foundation Analysis and Design, Bowles, page 409.
About distribution width for live load: There are many books or design specification explaining about equivalent width for example in AASHTO LRFD Bridge for one lane of highway with 3600mm width, the equilvalent width may be determinded as E=2440+0.12 S. S=Clear Span.
The distribution reinforcement placed in the bottom of all slabs transverse to the main reinforcement and this amount of distributin may be determided by percentage of main reinf = 55/sqrt(L), L is clear span.
Other minor reinforcement is determined based on the allowable width of crack.
About earthquake loading is neglected, especially for box culvert.
I used to use SAP software to design the box frame. And I think all the structure softwares are as good as SAP. Now depends on the designer how to determine the soil spring parameter dimension, reinforcement arrangement and allowable deflection based on the code used in your country.