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[yashrai]

Dear all,

as per IRC 6, clause 211.5.1.1, horizontal force at bearing level is given as max. of Fh - μ (Rg +Rq) or Fh/2 + μ (Rg +Rq), where Rg and Rq are dead load and live load reactions at free end.
I have the case that on pier on which two simply supported  spans rests one with fixed with free bearing and other with fixed bearing. I have calculated the live and dead load reaction on both of bearing.
Now my consfusion is as per the code do i have to use the reaction that comes on the free bearing only when calculating the horizontal force on fixed bearing?


Regards

[vikram.jeet]

First of all let us think of one span
S S span
Deck Expanding -
Traffic moving from fixed to free bearing ,, Deck expanding
Fixed bearing force = B - T
Free Bearing Force = T

Deck Contracting
Traffic again moving from Fixed to free Bearing side
Fixed Bearing Force = B/2 +T
Free bearing = B/2 - T  ( But not greater than T).

Now Two spans on pier having one span Fixed bearing (left on pier) and other span free bearing (Rt on pier) :
Traffic moving from left span to right span : Decks  expanding
Left span Fixed bearng F = B/2 +T  ( in direction of traffic)
Rt span free bearing force = B'/2 - T' ( in fir of traffic)
Hence force on pier additive of two

Traffic moving from Left to Rt,  Dech Contracting :-
Left span fixed bearing force = B-T ( in traffic dur)
Rt span free bearing force = T'  ( in traffic dir)
Both additives

B= Braking or other Horizontal force of Wind/ Eq
T = Temp movement,, frictional force  ( = u(DL+Ll) )

B' T' for other deck

Just a view for thought on design