CONCRETE STRUCTURES
CONCRETE STRUCTURES 
Rebar: ===== Bar Splice avoid welding wedged sleeve bar splice Bundling: up to 4 #11 Bending & Welding Limitations bent without heating max. heat 1,500 F bars partly embedded in concrete may not be bend no welding of crossing bars no tack welding creates metallurgical notch exceptions: engineer's permission Shipping Limitations: max. width 8'-0" max. length 60'-0" max. height 7'-4" Hooks: standard sizes according to ACI 318 Ties for square columns 4 bar 6 bar 8 bar 10 bar 12 bar 16 bar bundled bars ( 2 bar bundle) each corner 20 bars (3 bar bundle) 24 bars (4 bar bundle) Spiral Reinforcement No 3 9" min. diameter No 4 12" min. diameter Strength Requirements: Columns 3,000-7,000 psi Strength Variations due to: Batching Mixing Handling Compacting Curing Environmental Factors Loads on Formwork: pressure of concrete on vertical forms p = 150 + 9000 R/T p = lateral pressure psf R = rate of filling, ft/h T = temperature of concrete F Column Clamps steel strapping light-gauge econ-o-clamps symons column clamps recommended spacing of clamps see chart column width in 2" increments 12 x 12 14,16,18,20,22,24 14 x 14 14... 16 x 16 18 x 18 20 x 20 22 x 22 24 x 24
Sheet-Metal Columns with Capital form diameter 12 - 48 inches
Drilled Pier foundations look up allowable service load from chart based on shaft diameter bell diametr soil bearing pressure strength of concrete shaft height < = 30 x column diameter bell diameter < = 3 x column diameter 60 degree minimum slope
Maximum permissible w/c ratios: Concrete attacked by Substances: Durability of Concrete: resistance to wear abrasion scratching scrubbing scuffing weathering freeze-thaw ozone fading chemical fumes bactericidal UV ultraviolet radiation adhesion of coating delamination blistering dimensional stability shrinkage expansion volume change mechanical properties resistance to splitting bursting tearing fatigue Construction Joint: are formed when fresh concrete is placed against hardened concrete v - key u - key Expansion Joints are provided in long components to relieve compressive stresses that would otherwise result from temperature rise. Types: open joint allows moisture to evaporate sealed joint sealant primer applied to concrete joint filler controls depth of the sealant joints should be tooled min 1/4" full contact Contraction Joints = Control Joints are provided to permit concrete to contract during a drop in temperature and to permit d rying shrinkage without resulting uncontrolled random cracking width = h/4 to h/3
