Review Notes: Structural Notes

NOMINAL MAXIMUM SIZE OF COARSE AGGREGATE SHALL NOT BE LARGER THAN:

- 1/5 the narrowest dimension between side forms
- 1/3 the depth of slabs
- ¾ the minimum clear spacing between individual reinforcing bars or wires, bundles of bars, or prestressing tendons or ducts


DEFORMED REINFORCEMENTS

- ASTM A 184 – Fabricated Deformed Steel Bar Mats
- ASTM A 185 – Steel Welded Wire Fabric, Plain
- ASTM A 496 – Steel Wire, Deformed
- ASTM A 497 – Steel Welded Wire Fabric, Deformed
- ASTM A 615M – Deformed and Plain-Billet Steel Bars
- ASTM A 616M – Rail-Steel Deformed and Plain Bars
- ASTM A 617M – Axle-Steel Deformed and Plain Bars
- ASTM A 706M – Low-Alloy Steel Deformed Bars
- ASTM A 767M – Zinc-Coated (Galvanized) Steel Bars
- ASTM A 775M – Epoxy-Coated Reinforcing Steel Bars
- ASTM A 884M – Epoxy-Coated Steel Wire and Welded Wire Fabric
- ASTM A 934M – Epoxy-Coated Prefabricated Steel Reinforcing Bars


PRESTRESSING TENDONS

- ASTM A 416M – Steel Strand, Uncoated Seven-Wire
- ASTM A 421 – Uncoated Stress-Relieved Steel Wire
- ASTM A 722 – Uncoated High-Strength Steel Bar


CURING

- concrete (other than high-early strength) shall be maintained above 10°C and in a moist condition for at least the first 7 days after placement
- high-early strength concrete shall be maintained above 10°C and in a moist condition for at least the first 3 days


CONDUITS AND PIPES EMBEDDED IN CONCRETE

- they (including their fittings) shall not displace more than 4% of the area of cross section when embedded within a column
- they shall not be larger in outside dimension than 1/3 the overall thickness of slab, wall or beam in which they are embedded
- they shall be spaced not closer than 3 diameters or widths on center
- conduits, pipes and sleeves may be considered as replacing structurally in compression the displaced concrete, provided:
o they are of uncoated or galvanized iron or steel not thinner than standard Schedule 40 steel pipe
o they have a nominal inside diameter not over 50mm and are spaced not less than 3 diameters on centers
- concrete cover shall not be less than 40mm for concrete exposed to earth or weather, or less than 20mm for concrete not exposed to weather or in contact with ground
- reinforcement with an area not less than 0.002 times the area of concrete section shall be provided normal to the piping


CONSTRUCTION JOINTS

- construction joints in floors shall be located within the middle third of spans of slabs, beams and girders
- joints in girders shall be offset a minimum distance of 2 times the width of intersecting beams


STANDARD HOOKS

- 180-degree bend plus 4db extension, but not less than 60mm at free end of bar
- 90-degree bend plus 12db extension at free end of bar
- for stirrup and tie hooks:
o 16mm diameter bar and smaller – 90-degree bend plus 6db extension at free end of bar, or
o 20 and 25mm diameter bar – 90-degree bend plus 12db extension at free end of bar, or
o 25mm diameter bar and smaller – 135-degree bend plus 6db extension at free end of bar


MINIMUM BEND DIAMETERS

- bar size of 16mm and smaller (for stirrups and ties) – 4db (inside diameter)
- bar size of 10mm through 25mm – 6db
- bar size of 28, 32 and 36mm – 8db


SPACING LIMITS FOR REINFORCEMENT

- the minimum clear spacing between parallel bars in a layer shall be db but not less than 25mm
- the minimum clear spacing between parallel bars in 2 or more layers shall not be less than 25mm between layers
- in spirally reinforced or tied reinforced compression members, clear distance between longitudinal bars shall not be less than 1.5db or less than 40mm
- in walls and slabs other than concrete joist construction, primary flexural reinforcement shall not be spaced farther apart than 3 times the wall or slab thickness, nor farther than 450mm


BUNDLED BARS

- shall be limited to 4 bars in 1 bundle
- shall be enclosed within stirrups or ties
- bars larger than 36mm diameter shall not be bundled in beams
- individual bars within a bundle terminated within the span of flexural members shall terminate at different points with at least 40db stagger
- where spacing limitations and minimum concrete cover are based on bar diameter db, a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area
- minimum concrete cover shall be equal to the equivalent diameter of the bundle, but need not be greater than 50mm


PRESTRESSING TENDONS AND DUCTS

- center-to-center spacing of pretensioning tendons at each end of a member shall not be less than 5db for wire, nor 4db for strands


MINIMUM CONCRETE COVER FOR CAST-IN-PLACE CONCRETE (NONPRESTRESSED)

- concrete cast against and permanently exposed to earth – 75mm

- concrete exposed to earth or weather:
o 20mm through 36mm diameter bar – 50mm
o 16mm diameter bar and smaller – 40mm

- concrete not exposed to weather or in contact with ground:
o slabs, walls, joists:
 45 to 60mm diameter bars – 40mm
 36mm diameter bar and smaller – 20mm
o beams, columns:
 primary reinforcement, ties, stirrups, spirals – 40mm
o shells, folded plate members:
 20mm diameter bar and larger – 20mm
 16mm diameter bar and smaller – 12mm


MINIMUM CONCRETE COVER FOR PRECAST CONCRETE

- concrete exposed to earth or weather:
o wall panels:
 45mm and 60mm diameter bars – 40mm
 36mm diameter bar and smaller – 20mm
o other members:
 45mm and 60mm diameter bars – 50mm
 20mm through 36mm diameter bar – 40mm
 16mm diameter bar and smaller – 30mm

- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists:
 45mm and 60mm diameter bars – 30mm
 36mm diameter bar and smaller – 15mm
o beams, columns:
 primary reinforcement – db but not less than 15mm and need not exceed 40mm
 ties, stirrups, spirals – 10mm
o shells, folded plate members:
 20mm diameter bar and larger – 15mm
 16mm diameter bar and smaller – 10mm

MINIMUM CONCRETE COVER FOR PRESTRESSED CONCRETE

- concrete cast against and permanently exposed to earth – 75mm

- concrete exposed to earth or weather:
o wall panels, slabs, joists – 25mm
o other members – 40mm

- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists – 20mm
o beams, columns:
 primary reinforcement – 40mm
 ties, stirrups, spirals – 25mm
o shells, folded plate members:
 16mm diameter bar and smaller – 10mm
 other reinforcement – db but not less than 20mm


OFFSET BARS

- slope of inclined portion of an offset bar with axis of column shall not exceed 1 in 6
- portions of bar above and below an offset shall be parallel to axis of column
- lateral ties or spirals, if used, shall be placed not more than 150mm from points of bend
- offset bars shall be bent before placement in the forms
- where a column face is offset 75mm or greater, longitudinal bars shall not be offset bent.  Separate dowels, lap sliced with the longitudinal bars adjacent to the offset column faces, shall be provided


SPIRALS

- for cast-in-place construction, size of spirals shall not be less than 10mm diameter
- clear spacing between spirals shall not exceed 75mm or be less than 25mm
- anchorage of spiral reinforcement shall be provided by 1½ extra turns of spiral bar or wire at each end of a spiral unit
- spiral reinforcement shall be lap spliced by 48db but not less than 300mm or welded
- in columns with capitals, spirals shall extend to a level at which the diameter or width of capital is 2 times that of the column
- plain bars shall conform to one of the following specifications:
o ASTM A 615M
o ASTM A 616M
o ASTM A 617M
- plain wire shall conform to:
o ASTM A 82 – Steel Wire, Plain


TIES

- 10mm diameter lateral ties for longitudinal bars 32mm diameter or smaller
- 12mm diameter lateral ties for longitudinal bars 36 diameter and bundled bars
- vertical spacing of ties shall not exceed:
o 16db of longitudinal bars
o 48db of tie bars
o least dimension of compression member
- ties shall be arranged that no bar shall be farther than 150mm clear on each side along the tie
- ties shall be located vertically not more than ½ a tie spacing above the top of footing or slab in any story
- where beams or brackets frame from 4 directions into a column, termination of ties not more than 75mm below reinforcement in shallowest of such beams or brackets shall be permitted


SHRINKAGE AND TEMPERATURE REINFORCEMENT

- shrinkage and temperature reinforcement shall be spaced not farther apart than 5 times the slab thickness, or 450mm
- spacing of prestressed tendons shall not exceed 1.80m


T-BEAM CONSTRUCTION

- the flange and web shall be built integrally or otherwise effectively bonded together
- width of slab effective as a T-beam flange on each side of the web shall not exceed:
o ¼ the span length of the beam,
o 8 times the slab thickness, or
o ½ the clear distance to the next web
- for beams with a slab on one side only, the effective overhanging flange width shall not exceed:
o 1/12 the span length of the beam,
o 6 times the slab thickness, or
o ½ the clear distance to the next web
- transverse reinforcement shall be spaced not farther apart than 5 times the slab thickness, nor 450mm


JOIST CONSTRUCTION

- ribs shall not be less than 100mm in width and shall have a depth of not more than 3½ times the minimum width of rib
- clear spacing between ribs shall not exceed 750mm
- slab thickness over permanent fillers shall not be less than 1/12 the clear distance between ribs nor less than 40mm
- when removable forms or fillers are used, slab thickness shall not be les than 1/12 the clear distance between ribs, or less than 50mm
- where conduits or pipes are embedded within the slab, slab thickness shall be at least 25mm greater than the total overall depth of the conduits or pipes at any point


REQUIRED STRENGTH

- dead load and live load
o U = 1.4D + 1.7L
- dead load, live load and wind load
o U = 0.75 (1.4D + 1.7L + 1.7W)
o U = 0.9D + 1.3W
- dead load, live load and earthquake load
o U = 1.3D + 1.1L + 1.1E
o U = 0.99D + 1.1E
STRENGTH-REDUCTION FACTOR

- flexure without axial load, 0.90
- axial tension and axial tension with flexure, 0.90
- axial compression and axial compression with flexure:
o spiral reinforced, 0.75
o tie reinforce, 0.70
- shear and torsion, 0.85
- bearing on concrete, 0.70
- post-tensioned anchorage zones, 0.85


MINIMUM THICKNESS OF NONPRESTRESSED BEAMS OR ONE-WAY SLABS UNLESS DEFLECTIONS ARE COMPUTED (members are not supporting or attached to partitions or other construction likely to be damaged by large deflections)

- solid one-way slabs:
o simply supported, L/20
o one end continuous, L/24
o both ends continuous, L/28
o cantilever, L/10

- beams or ribbed one-way slabs:
o simply supported, L/16
o one end continuous, L/18.5
o both ends continuous, L/21
o cantilever, L/8

- for Fy other than 415Mpa, the values shall be multiplied by (0.4 + Fy/700)


DISTANCE BETWEEN LATERAL SUPPORTS OF FLEXURAL MEMBERS

- spacing of lateral supports for a beam shall not exceed 50 times the least width b of compression flange or face


LIMITS FOR REINFORCEMENT OF COMPRESSION MEMBERS

- minimum number of longitudinal bars in compression members shall be 3 for bars within triangular ties, 4 for bars within rectangular or circular ties, and 6 for bars enclosed by spirals


SPACING LIMITS FOR SHEAR REINFORCEMENT

- shall not exceed d/2 in non-prestressed members and 3/4h in prestressed members or 600mm

SPLICES

- lap splices shall not be used for bars larger than 36mm diameter
- lap splices of bars in a bundle shall be based on the lap splice length required for individual bars within the bundle
- individual bar splices within a bundle shall not overlap
- entire bundles shall not be lap spliced
- bars spliced by non-contact lap splices in flexural members shall not be spaced transversely farther apart than 1/5 the required lap splice length, or 150mm
- splices shall be staggered at least 600mm


WALLS

- minimum ratio of vertical reinforcement area to gross concrete area shall be:
o 0.0012 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420Mpa, or
o 0.0015 – for other deformed bars, or
o 0.0012 – for welded wire fabric (plain or deformed)



- minimum ratio of horizontal reinforcement area to gross concrete area shall be:
o 0.0020 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420 Mpa, or
o 0.0025 – for other deformed bars, or
o 0.0020 – for welded wire fabric (palin or deformed)

- in addition to the minimum reinforcement required, not less than 2-16mm diameter bars shall be provided around all window and door openings.  Such bars shall be extended to develop the bar beyond the corners of the openings but not less than 600mm


NON-BEARING WALLS

- thickness shall not be less than 100mm, or not less than 1/30 the least distance between members that provide lateral support


MINIMUM FOOTING DEPTH

- depth of footing above bottom reinforcement shall not be less than 150mm for footings on soil, or not less than 300mm for footings on piles


TRANSVERSE REINFORCEMENT (HOOPS)

- the first hoop shall be located not more than 50mm from the face of a supporting member
- maximum spacing of the hoops shall not exceed:
o d/4
o 8 times the diameter of the smallest longitudinal bar
o 24 times the diameter of the hoop bars
o 300mm
- where hoops are not required, stirrups shall be placed at no more than d/2 throughout the length of the member



STRUCTURAL STEEL


LIMITING SLENDERNESS RATIOS

- for members whose design is based on compressive force, the slenderness ratio preferably should not exceed 200
- for members whose designed is based on tensile force, the slenderness ratio preferably should not exceed 300


ALLOWABLE STRESSES

- for tension in structural steel in terms of gross area, 0.60Fy
- for tension in structural steel based on effective net area, 0.50Fu
- for tension on pin-connected members based on net area, 0.45Fy
- for tension on eyebars on the body area, 0.60Fy
- for flexural members with compact sections, Fb = 0.66Fy
- for flexural members with non-compact sections, Fb = 0.60Fy


PIN-CONNECTED MEMBERS

- minimum net area beyond the pinhole, parallel to the axis of the member, shall not be less than 2/3 of the net area across the pinhole
- width of the body of an eyebar shall not exceed 8 times its thickness
- pin diameter shall not be less than 7/8 times the eyebar width
- pinhole diameter shall be no more than 0.8mm greater than the pin diameter


SHEAR CONNECTORS

- shear connectors shall have at least 25mm of lateral concrete cover
- diameter of studs shall not be greater than 2½ times the thickness of the flange to which they are welded
- minimum center-to-center spacing of stud connectors shall be 6 diameters along the longitudinal axis and 4 diameters transverse to the longitudinal axis maximum center-to-center spacing of stud connectors shall not exceed 8 times the total slab thickness


WELDS

- weld access holes shall have a length from the toe of the weld preparation not less than 1½ times the thickness of the material in which the hole is made

- groove welds:
o effective area = effective length of the weld  x  effective throat thickness
o effective length = width of the part joined
o effective throat thickness of a complete-penetration groove weld = thickness of the thinner part joined
o minimum effective throat thickness of partial-penetration groove welds =
 3mm (thicker part joined to 6mm inclusive)
 5mm (thicker part joined over 6 to 12mm)
 6mm (thicker part joined over 12 to 20mm)
 8mm (thicker part joined over 20 to 38mm)
 10mm (thicker part joined over 38 to 57mm)
 12mm (thicker part joined over 57 to 150mm)
 16mm (thicker part joined over 150mm)
o effective throat thickness of a flare groove weld =
 flare bevel groove, 5/16R
 flare V-groove, ½R

- fillet welds:
o effective area of fillet welds = effective length x effective throat thickness
o effective throat thickness of a fillet weld = shortest distance from the root of the joint to the face of the diagrammatic weld
o minimum size of fillet welds =
 3mm (thicker part joined to 6mm inclusive)
 5mm (thicker part joined over 6 to 12mm)
 6mm (thicker part joined over 12 to 20mm)
 8mm (thicker part joined over 20mm)
o maximum size of fillet welds along edges =
 not greater than the thickness of the material (material less than 6mm thick)
 not greater than the thickness of the material minus 1.6mm (material 6mm or more in thickness)
o minimum effective length of a fillet weld designed on the basis of strength shall not be less than 4 times its nominal size
o if greater than 4 times its nominal size, the size of the weld should not exceed ¼ its effective length
o effective length of any segment of intermittent fillet welding shall not be less than 4 times the weld size, with a minimum of 38mm
o in lap joints, minimum lap shall be 5 times the thickness of the thinner part joined, but not less than 25mm
o slide or end fillet welds terminating at ends or sides, respectively, of parts or members shall, wherever practicable, be returned continuously around the corners for a distance not less than 2 times the nominal size of the weld

- plug and slot welds:
o diameter of the hole for a plug weld shall not be less than the thickness of the part containing it plus 8mm, nor greater than the minimum diameter plus 3mm or 2¼ times the thickness of the weld
o minimum spacing of lines of slot welds in a direction transverse to their length shall be 4 times the width of the slot
o minimum center-to-center spacing in a longitudinal direction shall be 2 times the length of the slot
o length of the slot shall not exceed 10 times the thickness of the weld
o width of the slot shall not be less than the thickness of the part containing it plus 8mm, nor shall it be larger than 2¼ times the thickness of the weld
o thickness of plug or slot welds in material 16mm or less thick = thickness of the material
o thickness of plug or slot welds in material over 16mm thick = ½ the thickness of the material but not less than 16mm


FASTENERS

- distance between centers of standard, oversized or slotted fastener holes shall not be less than 2 2/3 times the nominal diameter of the fastener
- maximum distance from the center of any rivet or bolt to the nearest edge of parts in contact shall be 12 times the thickness of the connected part, but shall not exceed 150mm


CAMBER

- trusses of 24.4m or greater span generally shall be cambered for approximately the dead-load deflection
- crane girders of 22.9m or greater span generally shall be cambered for approximately

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