Dear sir,
I designed a structure by using both method.in first method i deaigned it by composite beam method.and in second method i do it with composite deck.but by using composite beams giving lower utilization ratio than composite deck method.can you tell me the reason .As per my understading in in composite deck method it is not making the main beam as a composite beam.only secondary beams are composite in this case.Kindly advise what will be the best.should i change main beams only in composite beam in this case?both files are attached.2.
Thanking you,6557.STORE.std2 WITH DECK.std1715.STORE.std2.std
Gentle reminder
Yes the main reason is that the composite deck is assigning composite property to the beams in one direction. The direction in which the loads are distributed are shown using green arrows. You can also check which beams are being assigned composite properties by the program, using the Composite Deck tree structure. In your model without the deck, the composite properties have been defined for beams in both directions. Moreover the effective width for some of the beams like 286, 460 etc. has been considered as 2 m in your model 1715.STORE.std2.std whereas in the other one, the composite deck utility is considering half of that effective width for the slab. Also the density of concrete in your 1715.STORE.std2.std model has been specified as 24KN/m3 whereas it has been specified as 25KN/m3 in the other model.
Answer Verified By: waqar fazi
so which method you suggest?composite deck method is better if we define the main beams as a composite beams separately?i think stiffness also increased in this method.and if i change main beams as a composite in composite deck method then weight of the concrete slab also increased by effective width*span of primary beam .can we reduce this weight by putting the value of density 0 ?
so which method you suggest? composite deck method is better if we define the main beams as a composite beam separately? I think stiffness also increased in this method. and if I change main beams as a composite in composite deck method then the weight of the concrete slab also increased by effective width*span of primary beam .can we reduce this weight by putting the value of density 0?
The only purpose of using the Composite Deck is to let the software calculate the effective width of the slab. Depending on the deck direction (defined through the Create Direction button) beams in one direction will be defined as composite. If you need beams in both direction to be composite or have a complex shape of deck it is better to go with the explicit definition (manual). Stiffness due to the concrete slab is accounted for in both methods.