SE calculations

[Nathan110]

Q: Is it normal for a SE engineer to specify Spans of beams and not lengths? Are these normally for a builder to measure and order accordingly..

 

[Nathan110]

Asking as there for some beams (3 of there is a 0.7m descrepancy between the order based on spans and the length of steel beams needed...

 

[sxturbo]

Span is the distance between the walls, the length is the span plus the width of the platform the beam is to sit upon.

 

[^woody^]

An engineer only specifies the bearings, but will calculate the beam based on the spans. If you add the two together, you get the length.

Who actually designed or measured the requirement on site?

 

[Nathan110]

It seems the construction company has ordered the following beams based on spans and all were delivered. Unfortunately 2 openings need longer length beams and others will have to be cut. Just wanted to clarify where the error has happened. Should the builders be measuring up and ordering lengths and not spans or should the SE be providing lengths as well as spans.

 

[Nathan110]

Of the 8 beams, 3 beams will have to be re-ordered. Beam 2 resting on the external wall of the house and beam 3 which is the exterior wall of the extension. God knows how long that will take to come. Also cutting other beams to size...

All it needed was a measuring tape to prevent this but just perplexed how this happened. Is it duty of the SE or builder to check or provide lengths

 

[^woody^]

The builder or installer is always responsible for confirming the spans and measurements on site before ordering. No-one should order from a plan or document alone.

 

[Dereekoo]

Depends on the SE and his terminology/remit.i.e. design me a beam to span that 4m opening which is going to rest on walls made out of butter or concrete, the length of the butter one would be more than the concrete one cos of the different bearing capacities of the wall. Part and parcel of this are the padstone sizing , possibly non on concrete wall but largish ones on the butter walls. So its a question of what you or the builder asked of the SE. Ask the SE what he is playing at and ask for a copy of his calcs which will reveal all. Having said all that I would expect the given length to be the total required which will include the span unless he is supporting it with sky hooks fixed at the very ends of the span/beam

 

[Nathan110]

I have a 20 page document with all the calculations. In my correspondence with him he has said those are spans and not lengths. A builder with 'basic experience' should not know they are not the same thing is his response. Is this normal? The engineer for the construction project was away when these beams were ordered.. Says its normally only about a few cms but not as much as 0.7m-1m.

 

[Nathan110]

This is the email reply

 

[Nathan110]

Is it only a requirement of a SE to produce beam spans and not lengths as well as part of structural calcs? If so, why not?

 

[^woody^]

Depends on the SE and his terminology/remit.i.e. design me a beam to span that 4m opening which is going to rest on walls made out of butter or concrete, the length of the butter one would be more than the concrete one cos of the different bearing capacities of the wall. Part and parcel of this are the padstone sizing , possibly non on concrete wall but largish ones on the butter walls. So its a question of what you or the builder asked of the SE. Ask the SE what he is playing at and ask for a copy of his calcs which will reveal all. Having said all that I would expect the given length to be the total required which will include the span unless he is supporting it with sky hooks fixed at the very ends of the span/beam

What if the plans given to the engineer to work off are wrong or the brickie has built the wall one brick bigger?

 

[Nathan110]

Please see SE drawing and reference to the beam lengths. Seems very obvious the beams 2 and 3 need to be larger than the span opening but why not just provide that length if its very obvious how much needs to be added on. If It's not the SE's fault, I just want to establish if an SE not providing lengths is normal practice...

 

[Dereekoo]

What if the plans given to the engineer to work off are wrong or the brickie has built the wall one brick bigger?

Litigation

 

[Nathan110]

I wanted a 4m opening to the extension. Hence the beam is to be sitting on walls approx 900mm on one side and 600mm on the other. Clearly with a 5.5m full width needed a beam larger than 4m 'length' so as to accomodate the width of the padstone centres