## continuous beam

## continuous beam

(OP)

Is this correct?

A continuous beam is equivalent to a beam segmented which is momently joined.

How do we prove that? This has to do with finite element modeling. When we model a building in which a girder is divided into several girders where there are beams sitting in the perpendicular direction, can we assume that the girder is equivalent to a girder segmented with spacings of the beams without putting support below the segmented girder? In reverse, can we model a segmented girder without modeling it with a continuous girder without placing support below the segmented girder?

This is very basic but I just want to make sure. Thank you.

A continuous beam is equivalent to a beam segmented which is momently joined.

How do we prove that? This has to do with finite element modeling. When we model a building in which a girder is divided into several girders where there are beams sitting in the perpendicular direction, can we assume that the girder is equivalent to a girder segmented with spacings of the beams without putting support below the segmented girder? In reverse, can we model a segmented girder without modeling it with a continuous girder without placing support below the segmented girder?

This is very basic but I just want to make sure. Thank you.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

## RE: continuous beam

Mike McCann, PE, SE (WA, HI)

## RE: continuous beam

But do you mean there must be a support at the continuous girder or support at each of the segmented girder in building modeling? The segmented girder is actually a continuous beam but in building modeling, it is shown as segmented but momently connected.

I am afraid some steel detailing guys might interpret the segmented girders as segmented girders but not a continuous girder because, in modeling, I use segmented girders to replace a continuous girder were actually in steel detailing, the segmented girders are meant to be a continuous girder. How should it be drawn out on the modeling plan, construction plan, and steel detailing plan? I am using Midas Gen 2013. In Midas Gen, all the nodes are considered as momently connected. But there are beam-ends releases. You cannot place support in Midas Gen under the beam because the beam can only be simply supported through the means of beam ends release. I cannot put a boundary condition support there. Is this okay?

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

## RE: continuous beam

Mike McCann, PE, SE (WA, HI)

## RE: continuous beam

On the other hand, if I had 2 supports with a 30' simple span steel beam spanning between them, it would be the same as three 10' beams that were connected to transfer all forces between their joints. Is that what you are calling a continuous beam, mronlinetutor?

The 2nd one I describe would be analyze the same for forces, reactions and deflections but may not analyze the same for allowable loads if you do not correctly modify the lengths of the members for purposes of the steel checks. For example calling the length of the member as 10' would not yield the same allowables as 30'.

## RE: continuous beam

So is it okay to place a note on the girder and beam on the overall building modeling? The building is momently connected.

How else would you place the girders and beams with a 40'x40' grid columns?

Thank you.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

## RE: continuous beam

Looks like each girder has three point loads from the joists, with two more joists going directly to the columns, hence reducing the load to the girders.

Mike McCann, PE, SE (WA, HI)

## RE: continuous beam

A segmented beam/girder in FE program is a integral piece (continuously joined), provides that the internal forces and moments are passed through the interfaces (or joints) without discontinuity. I don't know whether "momently joined" is the correct description or not. If you have any doubt on the modeling technics prescribed by the program, why not go through an example problem in the user's manual, or try to model two beams in orthogonal directions, and verify the result by hand.

Label the beam and girder on plan, then cut an elevation view on beam-girder joint to show the details.

## RE: continuous beam

I may be color blind, but to me, the members on the perimeter are blue; the typical members running on column lines both N/S and E/W are olive green; most of the members running N/S on the page are red and there are a few that are yellow. In the central bay, there are orange members running in both directions, making a two way grid.

The columns are shown as round, but this may be merely a convenience to show column locations.

A continuous beam is a beam running continuously from end to end. It is not practical to provide beams 200' long, so full continuity is not possible.

"Momently joined"is undefined. Beam segments joined together by full strength welds would tend to render the girder fully continuous, but the reality is that full continuity is unlikely to be achieved in practice. This means that the deformation of the joint must be considered.BA

## RE: continuous beam

BA

## RE: continuous beam

## RE: continuous beam

does "The building is momently connected." have some special meaning to yous guys ?

another day in paradise, or is paradise one day closer ?

## RE: continuous beam

The interior vertical members are "puce" in the red family while the interior horizontal members are "Air Force Blue."

TTFN (ta ta for now)

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## RE: continuous beam

An old friend of mine, a mechanical engineer, used to kid me with "A wall is a concrete slab turns 90°, what difficult about it?" Yah, sort of ;)

## RE: continuous beam

Similar, to an extent, to the plate on plate problem you have commented on.