? OPENINGS IN COMPOSITE FLOOR DECKS Introduction Structural considerations for openings in composite floor decks • General information on the design of composite floor decks • Design of the steel deck as a form for construction loads • Design of the composite deck for superimposed loads • Openings in composite floor deck Non-structural considerations for openings (fire stopping) Creating the openings in composite floor decks Hilti CFS-CID MD System, an innovative solution for penetrations Appendix A Re
? INTRODUCTION Section 1 Composite floor deck construction has become very popular, because it combines structural efficiency with speed of construction to offer an economic solution for a wide range of building types including commercial, industrial, health, or residential building sectors. Figure 2 — Penetrations in composite floor decks Figure 1 — Composite floor deck construction Composite slabs consist of profiled steel decking with an in-situ reinforced concrete topping.
? STRUCTURAL CONSIDERATIONS FOR OPENINGS IN COMPOSITE FLOOR DECKS2 2.1 GENERAL INFORMATION ON THE DESIGN OF COMPOSITE FLOOR DECKS Composite floor consists of a concrete topping cast onto metal decking (Figure 3). Concrete is usually light weight or normal weight concrete, and the steel deck is a cold formed corrugated steel sheet spanning between steel joists or beams. Concrete slab Section 2 Based on the steel deck profile and loading on the deck, the deck can span 4’ up to 16’ between beams.
Structural considerations for openings in composite floor decks Note that the design of the steel deck to accommodate as a form is usually more critical than the design of the composite floor for superimposed loads since the steel deck profile and thickness shall be chosen such that the un-shored span of the steel deck can support the construction loads.
Structural considerations for openings in composite floor decks perimeter beams act as the beam flanges. Detailed design guide can be found in the Steel Deck Institute Diaphragm Design Manual, SDI-DDM. 2.2 O PENINGS IN COMPOSITE FLOOR DECK Openings and penetrations in composite slab decks are an unavoidable part of any structure to accommodate the installation of various mechanical and electrical application systems.
Structural considerations for openings in composite floor decks deck to support construction loads. Also, cutting the web of the steel deck before concrete is poured can reduce the steel deck vertical shear capacity locally around the opening and may result in deck web crippling under concentrated loads such as the weight of people or equipment on the deck during construction. Therefore, steel plates or frames may be needed to strengthen the edges of the opening and redistribute the load around the opening.
? NON-STRUCTURAL CONSIDERATIONS FOR OPENINGS (FIRE STOPPING) Section 3 Today’s building code’s primary focus is to safeguard the public health, safety and general welfare of the occupants. As part of this focus building codes require passive fire protection to minimize the spread of fire and smoke during a fire event. As a part of the overall passive fire protection scheme, the building is divided into compartments in order to contain the hot gases and smoke from spreading throughout the building.
Non-structural considerations for openings (fire stopping) The prescriptive code recognizes the critical function of the firestopping thus requiring both review and approval of plans prior to installation, and inspection of installed systems from the authority having jurisdiction or in some cases a third-party inspection firm. The inspector may ask the installer for the tested and listed system utilized to help avoid issues during the installation.
? CREATING THE OPENINGS IN COMPOSITE FLOOR DECKS There are two main methods to create small and medium size openings in composite floor decks: core-drilling the opening after concreting, and sleeving or boxing-out the opening before concrete poured. Each of these methods has its advantages and disadvantages as described below. Note that creating large size opening methods are out of the scope of this section.
Creating the openings in composite floor decks SLEEVING OR BOXING-OUT BEFORE CONCRETE POURED: Figure 14 — Configuration of sleeving and boxing-out openings Another approach to create the opening is to form an opening by setting sheet metal sleeves on the deck and then cut it prior or after concrete pouring. Depending on whether the steel deck is cut before or after concreting, the following are some examples of the typical installation process.
? HILTI CFS-CID MD SYSTEM, AN INNOVATIVE SOLUTION FOR PENETRATIONS Hilti has developed a new innovative solution, Hilti CFS-CID MD system, to overcome the above-mentioned problems. Hilti CFS-CID MD system is a cast-in firestop system to be used in composite floor decks for a variety of pipe materials and diameters. Section 5 Hilti CFS-CID MD system is composed of a firestop cast-in sleeve, a platform, a metal guide sleeve and a hole saw as shown in figure 16.
Hilti CFS-CID MD System, an innovative solution for penetrations THE INSTALLATION PROCESS INVOLVES 2 STEPS: Step one: Prior to concreting Platforms are set in the deck as shown in Figures 17a and 17b. After determining where CFS-CID MD sleeve must be located, platforms are attached to the deck with screws as shown in the diagram. Then the CFS-CID MD sleeves will be set on the platform.
? APPENDIX A Opening Reinforcement considerations for Superimposed Service Loads As mentioned in Section 2.2 (page 5) of this paper, there is no independent need to strengthen the steel deck as a form during construction using Hilti CFS-CID MD system since the deck is not cut prior to concrete poured and hardened.
Appendix A a) M ultiple inline platforms, placed in one deck flute: a) Multiple inline platforms, placed in one deck flute: ( ii ) (i) DECK OPENING ( iii ),(iv) 1'-0" Max (iv) (i) ( iii ) 2'-6" Max ( ii ) Direction of deck ( ii ) 1'-0" Max Direction of deck 1'-0" Max (i) PLAN DETAIL FOR SLEEVE PENETRATION (I) R ebar @ ¾” clear from bottom of the deck flute (size and length of rebar tbd by EOR.) (Ii) Two layers of rebar (size and length of rebar tbd by EOR.
Appendix A b)a) MMultiple ultiple platforms, platforms,placed placedinintwo twoor orthree threeadjacent adjacentdeck deckflutes: flutes: (i) (iv) ( iii ) DECK OPENING ( ii ) ( iii ) ( iv ) ( ii ) 3'-6" Max Direction of deck 2'-6" Max ( iii ) (i) PLAN DETAIL FOR SLEEVE PENETRATION (I) Rebar at ¾” clear from bottom of the deck flute (size and length of rebar tbd by EOR.) (Ii) Rebar at ¾” clear from top of deck (size and length of rebar tbd by EOR.) (Iii) Rebar dowels between sleeves.
? REFERENCES Standard for Composite Steel Floor Deck-Slabs, American National standards institute/ steel deck institute C1.0-2011 (ANSI/SDI C-2011) North American Specification for the Design of Cold-Formed Steel Structural members, American Iron and Steel Institute (AISI) Building Code Requirement for Structural Concrete, (ACI318-14) Luttrell, L. D., Diaphragm Design Manual, Third Edition (DDM03), Steel Deck Institute, 2004. Heagler, R. B., Deck Damage and Penetrations, Steel Deck Institute, 2000.
Hilti, Inc. (U.S.) 1-800-879-8000 en español 1-800-879-5000 www.hilti.com DBS • 06/19 ? Hilti (Canada) Corporation 1-800-363-4458 www.hilti.
