Design of Construction Loads in Concrete / Steel Structures

[Whodapookie]

I am trying to understand why the steel guys use 20psf for construction load while the concrete guys use 50psf.

The IBC2006 references the ACI which ACI 6.1.5 references ACI R347 where it states in 2.2.1 "The formwork should be designed for a live load of not less than 50psf of horizontal projection" while the AISC just references ASCE 7 for design loads which does not mention construction loads at all.

The ASCE 37-02 breaks construction loads down to 4 groups:
Very Light Duty (20psf), Light Duty (25psf), Medium Duty (50psf), & Heavy Duty (75psf). The VLD is for roofs, LD for Concrete placement with hose, MD Concrete placement with bucket, HD Concrete placement with buggy.

The Steel Deck Institue (SDI) uses 20psf for construction load for their products (50psf before concrete placement and then concrete weight + 20psf during/after placement.

I don't consider the steel "Formwork", but if you are comparing buildings side by side, the concrete guys designed their building with a 30psf premium over the steel guys during the construction phase.

What is the code specified requirements for Steel members supporting concrete?

 

[RARWOOD]

I don't know what the codes require, however when I worked for a firm that did a lot of steel systems with composite deck with concrete topping the firm's standard was to use 60 p.s.f. construction load. Although this appears to be on the high side the firm I worked for found that by using 60 p.s.f. they reduce the number of construction related problems.

 

[Whodapookie]

Wow, 60 sounds pretty large for construction. I did go through the SDI MOC2 and believe they use the larger of 50psf construction or weight of concrete + 20psf. This actually makes sense to me.

RARMBJ, what do you mean by "construction related problems"? BTW, Thanks for responding!