PRODUCT LOAD TABLES - Coreslab Structures

1 PRODUCT LOAD TABLES 1 Under service loads, the bottom of the beam will develop hairline cracks. Ordinary concrete Beam Even without a load, the ordinary concrete beam must carry its own considerable weight. This leaves only a portion of its strength available to resist added loads. The internal upward force along the length of the beam counteracts the external service loads applied to the member. WHAT IS precast /PRESTRESSED concrete ? WHY USE precast /PRESTRESSED concrete ? Prestressed concrete Beam Prestressed or pretensioned before it leaves the plant, a slight arch or camber is noticeable.

2 Energy is stored in the unit by the action of the highly tensioned steel which places a high compression in the lower portion of the member. An internal upward force is thereby created which in effect relieves the beam of having to carry its own weight. precast /PRESTRESSED concrete is an architectural and structural material possessing great strength. Specifically, PRESTRESSED concrete has unique characteristics that allow pre-determined, engineered stresses to be placed in members to counteract stresses that occur when the unit is subjected to service loads.

3 This is accomplished by combining the best properties of two quality materials: high strength concrete for compression and high tensile strength steel strands for tension. Actually, prestressing is quite simple. High tensile strands are stretched between abutments at each end of long casting beds. concrete is then poured into the forms encasing the strands. As the concrete sets, it bonds to the tensioned steel. When the concrete reaches a specified strength, the strands are released from the abutments.

4 This compresses the concrete , arches the members, and creates a built-in resistance to service loads. Rapid Construction Conserves EnergyVersatility of DesignPrecast/Prestressed concreteconstruction gets the job donesooner. The manufacturing ofprecast/prestressed membersand site preparation can proceedsimultaneously. Early occupancyprovides obvious benefits to theclient. precast /Prestressed concretecomponents can improve thethermal storage potential of abuilding. If effectively conservesenergy required for heating andcooling.

5 precast /Prestressed concrete buildings are not only functional but beautiful as well. Numerous panel configuration design possibilities are available. Resists Fire Column-Free Long SpansMaintenance FreeDurability and fire resistancemean low insurance premiumsand greater personnel who investigate life cyclecosting will appreciateprestressed concrete s excellentfire resistance characteristics. With fewer columns and moreusable floor space, prestressedconcrete provides greaterfreedom for space utilization.

6 precast /Prestressed concrete does not require painting and is free from corrosion. Its durability extends building life. 2 TOTAL Structures Desert Ridge Corporate Center Parking Phoenix, Arizona Integrated Medical Services Avondale, Arizona North Mountain Integrated Medical Services Phoenix, Arizona Granite Street Parking Structure Prescott, Arizona Harrah s Entertainment Corporate Office Las Vegas, Nevada 3 The following pages contain load TABLES for the standard products available from Coreslab Structures (ARIZ) Inc.

7 Load capacities are in conformance with the American concrete Institute "Building Code Requirements for Structural concrete (ACI 318-05)". However, values given in the TABLES are intended for preliminary member selections, not final designs. These values assume that the safe superimposed load is composed of 60% dead load and 40% live load. In some cases, loads in excess of those shown can be accommodated by modifying the general parameters such as concrete strength and/or reinforcing patterns.

8 MATERIAL PROPERTIES concrete : Compressive Strength Final (28-day) = 5000 psi ( precast ) = 3000 psi (Topping) At Prestress Release = 3500 to 4000 psi when maximum load is used. Otherwise a lower strength may be Weight = 150 pcf Modulus of Elasticity = W 33 FLEXURAL MEMBERS In general, maximum spans shown for the various prestressing conditions will result in an upward camber under dead load, after loss of prestress has occurred. Roof deflection, however, should always be checked. It is recommended that a positive slope always be provided for roofs.

9 Whenever span-to-depth ratio exceeds 30 for double tees a positive roof slope is essential to preclude ponding. Also, see the 2006 Edition International Building Code IBC. Topping Slab Design by Others For composite members, reinforcement ( , welded wire fabric or reinforcing bar) is generally required for the structural design of the topping slab. The Engineer of Record should furnish this design. Steel: Prestressing Strand: Sizes: 1/2" Diameter Ultimate Strength = 270,000 psi Initial Tension = 70 to 75% of Ult. Strength Modulus of Elasticity = 28,000,000 psi Reinforcing Steel: Bar Sizes: 4, 5 and 6 are A706, Grade 60 Bar Sizes: 7 and larger are A615, Grade 60 The required depth of a beam or slab is influenced by the ratio of live load to total load.

10 When this ratio is high, deeper sections may be needed. PREFACE TO PRODUCT LOAD TABLES DESIGN RECOMMENDATIONS Maximum Bottom Range of Maximum precast Tension Stress Span-To-Depth Ratio Double Tee Floor Slabs 12cf' 25 to 30 Double Tee Roof Slabs 12cf' 35 to 40 Inverted Tee or ELL Beams