USTCA Building Technology 3 Handout PDF

University of Santo Tomas College of Architecture Building Technology 3 REINFORCED CONCRETE, béton armé, Concrete is not good in carrying tension and ferroconcrete...

University of Santo Tomas College of Architecture Building Technology 3 REINFORCED CONCRETE, béton armé, Concrete is not good in carrying tension and ferroconcrete only the steel bars are carrying all the stresses Concrete in which steel reinforcement is embedded due to bending which is tension in such a manner that the two materials act There must be no slippage between concrete together in resisting forces and steel bars historical note: In 1867, Joseph Monier (France) Plain concrete used the concept of iron reinforcing bars when he Concrete having no reinforcement, or reinforced reinforced William Ward’s (US) flower pots using only for drying shrinkage or thermal stresses wire. Ferrocement BEAM Constructed of cement mortar over wire mesh that A rigid structural member designed to carry and has been pre-shaped over a mold transfer transverse loads across space supporting elements Cast-in-place concrete, cast in-situ, in-situ concrete Concrete which is deposited in the place where it is Simple beam required to harden as part of the structure, as A beam having a single span supported at its end opposed to pre-cast concrete without a restraint at the support Reinforcement Semi-continuous beam A system of steel bars, strands or wires for A beam with two spans with or without restraint at absorbing tensile, shearing and sometimes the two extreme ends compressive stresses in a concrete member or structure Cantilever beam A beam supported on one end and the other end Deformed bar projecting beyond the support, beam or wall A reinforcing bar hot-rolled with surface deformations to develop a greater bond with Continuous beam concrete A beam that rests on more than two supports Tension reinforcement T-beam Reinforcement designed to absorb tensile stresses Part of the floor and beam unit when poured (tensile stress, normal stress, tension: resistance of simultaneously thereby producing a monolithic an object to a force tending to tear it apart) structure where the portion of the slab at both sides of the beam serves as flanges of such beam Compression reinforcement Reinforcement designed to absorb compressive Reinforced concrete beam stresses (compressive strength is the maximum A concrete beam designed to act together with compressive stress that, under a gradually applied longitudinal and web reinforcement in resisting load, a given solid material can sustain without applied forces, formed and placed along with the fracture) slab it supports Balanced section Beam Nomenclature: A concrete section in which the tension reinforcement theoretically reaches its specified Effective Depth of Section yield strength as the concrete in compression The depth of a concrete section measured from the reaches its assumed ultimate strain. A design so compression face to the centroid of the tension proportional such that the maximum stresses in reinforcement. the concrete and steel are reached simultaneously so that they fail together. Bar Spacing The center-to-center spacing of parallel bars, the Over-reinforced section resulting clear distance between the bars being A concrete section in which the concrete in regulated by bar diameter, maximum size of coarse compression reaches its assumed ultimate strain aggregate, and thickness of the concrete section. before the tension reinforcement reaches its specified yield strength. This is a dangerous Span of Supports condition since failure of the section could occur Refers to the distances between posts, columns or instantaneously without warning. This type of supporting walls. design is not advisable because concrete fails abruptly in compression. Concrete Layer, Concrete Cover The amount of concrete required to protect steel Under-reinforced section reinforcement from fire and corrosion, measured A concrete section in which the tension from the surface of the reinforcement to the outer reinforcement reaches its specified yield strength surface of the concrete section. before the concrete in compression reaches its assumed ultimate strain. This is a desirable Bond condition since failure of the section would be The adhesion between two substances, as concrete preceded by large deformations, giving prior and reinforcing bar warning of impending collapse. In this particular type of design, the steel fails first while the Bond Stress concrete has not yet reached its allowable values The adhesive force per unit area of contact but the failure is gradual with steel yielding. between a reinforcing bar and the surrounding concrete developed at any section of a flexural Assumptions in Elastic Theory in Concrete member. Plane section remains plane before and after bending occurs Developmental Length Concrete is elastic; that is the stress of concrete The length of the embedded reinforcement varies from zero at the neutral axis to a required to develop the design strength of maximum at the extreme fibers reinforcement at a critical section Acknowledgement: Arch. Raffy Cueva Alli 1 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Specifications for Blended Hydraulic Cements Embedment Length (ASTM C 595), excluding Types S and SA which Length of embedded reinforcement provide are not intended as principal constituents of beyond a critical section structural concrete End Anchorage Admixtures Length of reinforcement or mechanical anchor or Admixtures to be used in concrete shall be hook or combination thereof beyond point of zero subject to prior approval by the Engineer stress in reinforcement An admixture shall be shown capable of maintaining essentially the same composition Hook and performance throughout the work as the A bend or curve given to the end of a tension bar to product used in establishing concrete develop an equivalent embedment length, used proportions where there is sufficient room to develop an Admixtures containing chloride ions shall not embedment length be used in pre-stressed concrete containing aluminum embedments if their use will Longitudinal Reinforcement produce deleterious concentration of chloride Reinforcement essentially parallel to the horizontal in the mixing water surface of a slab or to the long axis of a concrete beam or column Concrete aggregates shall conform to one of the following specifications: Percentage Reinforcement Specifications for Concrete Aggregates (ASTM C The ratio of effective area of reinforcement to 33) effective area of concrete at any section of a Specifications for Lightweight Aggregates for reinforced concrete member, expressed as a Structural Concrete (ASTM C 330) percentage Nominal maximum size of aggregates shall not be Top Bar larger than: Any of the longitudinal bars serving as tension 1/5 the narrowest dimension between sides of reinforcement in the section of a concrete beam or forms, nor slab subject to a negative moment 1/3 the depth of slabs, nor 3/4 the maximum clear spacing between Bottom Bar individual reinforcing bars, or pre-stressing Any of the longitudinal bars serving as tension tendons or ducts reinforcement in the section of a concrete beam or slab subject to a positive moment Water Water used in mixing concrete shall be clean Web Reinforcement and free from injurious amounts of oils, acids, Reinforcement consisting of bent bars or stirrups, alkalis, salts, organic materials, or other places in a concrete beam to resist diagonal tension substances that may be deleterious to concrete or reinforcement. Bent Bar Mixing water for pre-stressed concrete or A longitudinal bar bent to an angle of 30* or more concrete that will contain aluminum with the axis of the concrete beam, perpendicular embedments, including that portion of mixing to and intersecting the cracking that could occur water contributed in the form of free moisture from diagonal tension on aggregates shall not contain deleterious amounts of chloride ions. Bend Reinforcing Bars Reinforcing bars that are bent up on or near the Metal Reinforcement inflection point are extended at the top of the beam across the support towards the adjacent span Reinforcement shall be deformed reinforcement, except that consisting of structural steel, steel pipe, steel tubing may be No Bent Bars used. Bars that are not bent, an additional straight reinforcing bar place on the top of the beam across Reinforcement to be welded shall be indicated the supports to the required length and other in the drawings and welding procedure to be straight additional bars are also placed at the used shall be specified. bottom center of the beam span where positive moment develops Reinforcement Details Truss Bar A longitudinal bar bent up or down at points of Standard Hook moment reversal in a reinforced concrete beam A 90°, 135° or 180° bend made at the end of a reinforcing bar according to industry standards Stirrup with radius based on the bar diameter. Any of the U-shaped or closed-loop bars placed perpendicular to the longitudinal reinforcement of Standard Hooks (NSCP, 4th ed. 1992) a concrete beam to resist the vertical component of 180° bend plus 4db extension, but not less than diagonal tension 65 mm at free end of bar. 90° bend plus 12db extension, at free end of bar. BUILDING CODE REQUIREMENTS FOR For Stirrups and Tie Hooks REINFORCED CONCRETE (ACI 318-77) 16 mm bar and smaller, 90° bend plus 6db Standard for Tests and Materials: extension at free end of bar. 20 mm bar and 25 mm, 90° plus 12db Cement shall conform to one of the following extension at free end of bar. specifications for Portland Cement: 25 mm bar and smaller, 135° bend plus 6db Specifications for Portland Cement (ASTM 150) extension at free end of bar. Acknowledgement: Arch. Raffy Cueva Alli 2 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 o Bar larger than 32 mm shall not be bundled Minimum Bend Diameters in beams. Diameter of bend measured on the inside of the o Individual bars within a bundle terminated bar other than for stirrups and tie4s in sizes within the span of flexural members shall 10mm through 15mm diameter, shall not be terminate at different points with at least less than indicated on the table below. 40db, stagger. Inside diameter of bend for stirrups and ties o Where spacing limitations and minimum shall not be less than 4db for 16 mm and concrete cover are based on bar diameter smaller. db, a unit of bundled bars shall be treated as Inside diameter of bend in welded wire fabric a single bar of diameter derived from the (plain or deformed) for stirrups and ties shall equivalent total area. not be less than 4db for deformed wire larger than D6 and 2db for all other wires. Bends with Concrete Protection for Reinforcement inside diameter of less than 8db shall not be Cast in place Concrete Minimum less than 4db from nearest welded intersection. (Non-prestressed) Cover (mm) Concrete cast against and permanently 75 Minimum Diameters of Bend exposed to earth Bar Size Minimum Diameter Concrete exposed to earth or weather: 10 mm to 25 mm 6db 20 mm through 36mm bars 28 mm to 32 mm 8db 16 mm bar, W31 or D31 wire and smaller 50 36 mm 10db 40 Concrete not exposed to weather or in Bending contact with ground: All reinforcement shall be bent cold, unless Slabs, Walls, Joists, 32 mm bar and 20 otherwise permitted by the Engineer. smaller Reinforcement partially embedded in concrete Beams, Columns: shall not be field bent, except as shown on the Primary reinforcement, ties, stirrups, 40 drawings or permitted by the Engineer. spirals Shell, Folded Plate members: Surface Conditions of Reinforcement 20 mm bar and larger 20 At time concrete is placed, metal reinforcement 16 mm bar, W31 or D31 Wire and smaller 15 shall be free from mud, oil or other nonmetallic coatings that adversely affect bonding capacity. Precast Concrete (Manufactured Under Minimum Metal reinforcement, except pre-stressing Plant Control Conditions) Cover (mm) tendons, with rust, mill scale, or a combination of both shall be considered satisfactory, Concrete exposed to earth or weather: provided minimum dimensions and weight of a Wall panels: hand-wire-brushed test specimen are not less 32 mm bar and smaller than applicable ASTM specifications 20 requirements. Other members: 20 mm through 32mm bar 40 Placing Reinforcements 16 mm bar, W31 or D31 wire and smaller 30 Reinforcement, pre-stressing tendons and Concrete not exposed to weather or in ducts shall be accurately placed and adequately contact with ground: supported before concrete is placed, and shall Slabs, Walls, Joists: be secured against displacement within 32 mm bar and smaller 15 tolerable limits. Beams, Columns: db but not Welding of cross bars shall not be permitted for Primary Reinforcement less than 15 assembly of reinforcement unless otherwise and need not authorized by the Engineer. exceed 40 Ties, Stirrups, Spirals 10 Spacing Limits for Reinforcements Shell, Folded Plate members: 1. The minimum clear spacing between parallel 20 mm bar and larger 15 bars in a layer shall be db, but not less than 25 16 mm bar, W31 or D31 Wire and smaller 10 mm. 2. Where parallel reinforcement is placed in two or more layers, bars in the upper layer shall be Prestressed Concrete Minimum placed directly above bars in the bottom layer Cover (mm) with clear distance between layers not less than Concrete cast against and permanently 75 25 mm. exposed to earth 3. In spirally reinforced or tied reinforced Concrete exposed to earth or weather: compression members, clear distance between Wall Panels, Slabs, Joists longitudinal bars shall not be less than 1.5db Other Members 25 nor more than 40 mm. 40 4. Clear distance limitation between bars shall Concrete not exposed to weather or in apply also to the clear distance between a contact with ground: contact tap splice and adjacent splices or bars. Slabs, Walls, Joists 20 5. In walls and slabs other than concrete joist Beams, Columns: construction, primary flexural reinforcement Primary Reinforcement 40 shall be spaced not farther than three times the Ties, Stirrups, Spirals 25 wall or slab thickness nor more than 450 mm. Shell, Folded Plate members: 6. Bundled bars shall be done in the following 16 mm bar, W31 or D31 Wire and smaller 10 manner: Other Reinforcement o Groups of parallel reinforcing bars bundled db but not in contact to act as a unit shall be limited to less than 20 four in any one bundle. Source: National Structural Code of the Philippine (NSCP) o Bundled bars shall be enclosed within stirrups or ties. Acknowledgement: Arch. Raffy Cueva Alli 3 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 than 75 mm below lowest reinforcement in REINFORCED CONCRETE COLUMN shallowest of such beams or brackets. A concrete designed to act together with vertical and lateral reinforcement in resisting applied ACI Specification for Axially Loaded Tied Columns forces. Reinforced concrete column constituting the Particulars Remarks principal supports for a floor or roof should have a Min. Cross sectional area of 60,000mm2 minimum diameter of 10 in (254 mm) or if column Ag rectangular in section, a minimum thickness of 8 in Minimum thickness of 200mm (203 mm) and a minimum gross area of 96 sq. in column (61935 sq. mm). Minimum covering of ties 1. Not less than 40 mm 2. Not less than 1.5 times Short Column the max. size of A column having an unsupported height not coarse aggregate greater than 10 times the shortest lateral Minimum diameter of lateral 10mm diameter dimension of the cross section ties Lateral ties spacing 1. Not more than 16 bar Long Column diameter When the unsupported height is more than 10 2. Not more than 48 tie times the shortest lateral dimension of the cross diameter section 3. Not more than the least dimension of Tied Column column A concrete column reinforced with vertical bars Clear distance between Not less than 1.5 times the and individual lateral ties. Lateral ties should have horizontal bars bar diameter nor less than a diameter of at least 10 mm (3/8 in.) spaced apart 1.5 times the max. size of not more than 48 tie diameters, 16 bar diameters aggregates or the least dimension of the column section Minimum number of bars 4-16 mm diameter Pg (ratio of glass reinf. area 0.01 – 0.04 Vertical Reinforcement to cross sectional area) Longitudinal reinforcement placed in concrete Source: American Concrete Institute (ACI) column to absorb compressive stresses, resist bending stresses and reduce the effects of creep Spiral Column and shrinkage in the column. A concrete column with spiral reinforcement enclosing a circular core reinforced with vertical Lateral Reinforcement bars. Spiral reinforcement or lateral ties placed in a concrete column to laterally restrain the vertical Lateral Reinforcement for Compression Members - reinforcement and prevent buckling. Spiral Reinforcement 1. Spirals shall consist of evenly spaced Spiral Reinforcement continuous bar or wire of such size and so Lateral reinforcement consisting of an evenly assembled to permit handling and placing spaced continuous spiral held firmly in place by without distortion from designed dimensions. vertical spacers. 2. For cast-in-place construction, size of spirals shall not be less than 10 mm diameter. Bundled Reinforcement 3. Clear spacing between spirals shall not exceed Reinforcement employed consisting of two to four 75 mm nor less than 25 mm bars tied in direct contact with each other to serve 4. Anchorage of spiral reinforcement shall be or act as one unit reinforcement placed at the provided by 1 ½ extra turns of spiral bar or corner of lateral ties. wire at each end of a spiral unit. 5. Splices in spiral reinforcement shall be lap splices of 48db but not less than 300 mm of Lateral Reinforcement for Compression Members - welded. Lateral Ties 6. Spirals shall extend from top of footing or slab 1. All non-pre-stressed bars shall be enclosed by in any story to level of lowest horizontal lateral ties, at least 10 mm in size for reinforcement in members supported above. longitudinal bars 32 mm or smaller, and at least 7. Where beams or brackets do not frame into all 12mm in size for 36 mm and bundled sides of a column, ties shall extend above longitudinal bars. Deformed ire or welded wire termination of spiral to bottom of slab or drop fabric of equivalent area is allowed. panel. 2. Vertical spacing of ties shall not exceed 16 8. In columns with capital, spirals shall extend to a longitudinal bar diameter, 48 tie diameters, or level at which the diameter or width of capital least dimension of the compression member. is two times that of the columns. 3. Ties shall be arranged such that every corner 9. Spirals shall be held firmly in place and true to and alternate longitudinal bar have lateral line. support provided by the corner of a tie with an included angle of not more than 135 degrees ACI Specification for Axially loaded Spiral Column and no bar shall be farther than 150 mm clear Particulars Remarks on each side along the tie from such a laterally Minimum diameter 250mm supported bar. Where longitudinal bars are Minimum diameter of spiral 10mm diameter located around the perimeter of a circle, a ties complete circular tie is allowed. Spacing of spiral ties 1. Not more than 75mm 4. Ties shall be located vertically not more than 2. Not less than 25mm 1/2 a tie spacing above the top of footing or 3. Not less than 1.5 times slab in any story, and shall be spaced as the size of course provided herein to not more than 1/2 a tie aggregates spacing below the lowest horizontal 4. 1/6 core diameter reinforcement in slab or drop panel above. Minimum number of bars 6-16 mm diameter 5. Where beams or brackets frame four directions Clear distance between 1. Not less than 1.5 times into a column, ties may be terminated not more longitudinal bars bar diameter Acknowledgement: Arch. Raffy Cueva Alli 4 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 2. Not less than 1.5 times distance between the two positions is not more max. size of coarse than 75mm (3 inches). In crimping or offsetting aggregate the bars, the angle of bend shall not be more Pg (ratio of gross reinf. area 0.01-0.08 than one horizontal to six vertical (1:6). Extra to gross cross sectional lateral tiles shall be provided at the lower end area of column) of the bend to carry at least 1.25 of the outside Source: American Concrete Institute (ACI) thrust caused by the inclined position of the bar, and this may be satisfied by providing at Composite Column least two extra hoops to hold the bent bars at A type of column where structural steel is the beginning of the bend, these hoops spaced embedded into the concrete core of a spiral column close together. 5. Lateral ties and spirals shall be provided for the Combined Column vertical bars of the column within the depth of A column with a structural steel encased in a the beams and/or girders at the intersection concrete of at least 7cm thick reinforced with wire with the column and spaced not more than 0.10 mesh surrounding the column at a distance of 3 cm meters on centers. inside the outer surface of the concrete covering. Minimum Thickness of Non-pre-stressed Beams Lally Column A fabricated post made of steel provided with a Notes on Concrete Beams plain flat steel bar or plate, which holds girder, girt 1. The clear distance from the bar to the farther or beam. The steel pipe is sometimes filled with face of the wall shall not be less than 4 bar concrete for additional strength and protection diameters (4db) if reinforcing bars end in a from rust or corrosion wall. 2. Bars may be bundled in twos, threes, fours, as Special Reinforcement Details for Columns indicated on drawings, such bundled bars shall be securely wired together to prevent them Offset Bars from separating. 1. The slope of an inclined portion of an offset bar 3. Use 25mm separator at 1m apart for two or with axis of column shall not exceed 1 in 6. more layers of reinforcing bars, with the bars 2. Portions of bar above and below an offset shall not bundled. be parallel to axis of column. 4. Beam reinforcing bars supporting slab 3. Horizontal support at offset bends shall be reinforcement shall be 25mm clear from the provided by lateral ties, spirals or parts of floor bottom of the finish. The clear concrete construction. Horizontal support provided shall covering between the face of the beam at the be designed to resist 1 ½ times the horizontal bottom of the sides shall be 350mm. component of the computed force in the 5. When the beam crosses a girder, rest beam bars inclined portion of an offset bar. Lateral ties or on top of girder bars. spirals, if used shall be placed not more than 6. Beam reinforcing bars shall be symmetrical 150mm from points of bend. about the vertical axis whenever possible, and 4. Offset bars shall be bent before placement of about the center line at mid-span except for end forms. spans and where otherwise shown. 5. When a column is offset 75 mm or greater, 7. Stirrups for rectangular beams without flanges longitudinal bars shall not be offset bent. shall be closed stirrups. Stirrups for tee beams Separate dowels, lap splices with the with flanges on one side only shall likewise be longitudinal bars adjacent to the offset column closed stirrup. Stirrups for tee beams with faces shall be provided. flanges on both sides may be U stirrups. U stirrups may be placed alternating inverted and Notes on Concrete Columns upright position. 1. Columns shall be of the sizes indicated in the schedule or as detailed in drawings and reinforced as shown, with deformed bars only. Vertical bars of columns shall have 90° bend FLOOR SYSTEM and anchored at the supporting footing or other The horizontal planes that supports both live loads supporting member. and dead loads and transfer their loads 2. Concrete protective covering from the face to horizontally across to a beam, column or to load- the reinforcing steel shall be 40 mm. Splices of bearing walls. verticals bars shall be staggered as much as possible, located preferably at the middle half Live load of the column height. Not more than alternate Refers to those movable loads imposed on the floor bars shall be spliced at any one level bar splices such as people, furniture and the like. may be lapped splices, or electrically butt- welded that can develop the full capacity of the Dead load bar. Refers to the static load such as the weight of the 3. The spacing of lateral ties shown in the construction materials, which generally carry the schedule are maximum spacing which shall be live load. used only outside the heights and away for joints, where a reduced spacing of not more Environmental load than 0.10 meter on center is required. The Consists of wind pressure and suction, earthquake distance which is measured upward from top of load, rainwater on flat roof and forces caused by footing or floor lines, and downward from temperature changes or differentials. bottom and deepest beam or girder, shall be the largest of the following: (a) maximum column; Reinforced Concrete Slab (b) one-sixth (1/6) of the clear of the column; A rigid planar structure of concrete designed to act and (c) 457mm (18 inches) together with principal and secondary 4. If the column is reduced in size at an upper reinforcements in resisting applied forces. floor, the vertical bars of the column from the lower floor may be crimped of offset to the new Slab Nomenclature: position at the upper column if the horizontal Acknowledgement: Arch. Raffy Cueva Alli 5 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Principal Reinforcement S/L > 0.5, it is two-way slab Reinforcement designed to absorb the stress from Min. thickness t = Perimeter/180 applied loads and moments. Max. spacing of main bars = 3t not > 450mm Spacing of bars within column strip is 3/2 Shrinkage Reinforcement, Temperature times the spacing at the center reinforcement Reinforcement placed perpendicular to the Beam-and-Girder Slab principal reinforcement in a one-way slab to A one-way slab supported by secondary beams absorb the stresses resulting from shrinkage or which turn are supported by primary beams of changes in temperature. girders. Concrete Topping Continuous Slab A thin layer of high-quality concrete placed over a A reinforced concrete slab extending as structural concrete to form a floor surface. unit over three or more supports in a given direction. A continuous slab is subject to lower Bonding Layer bending moments than a series of discrete, simply A thin layer of mortar spread on a moistened and supported slabs. prepared existing concrete surface prior to laying a new concrete slab. Flat Plate A concrete slab of uniform thickness reinforced in Expansion Joint two or more directions and supported directly by A joint or gap between adjacent parts of a building columns without beams or girders. Flat plates are or structure or concrete work which permits their suitable for short to medium spans with relatively relative movement due to temperature changes (or light live loads. Since there no column capitals or other conditions) without rupture or damage. (Also drop panels, shear governs the thickness of a flat called contraction joint) plate. Construction Joint Flat Slab A joint where two successive placements of A flat plate thickened at its column supports with concrete meet column moment-resisting capacity. Flat slabs are suitable for heavy loaded spans. Isolation Joint Often called Expansion joint, it allows movement Waffle Slab between concrete slab and adjoining columns and A two-way concrete slab reinforced by ribs in two walls of a building. directions. Waffle slabs are able to carry heavier loads and spans longer distances than flat slabs. Control Joint Supporting beams and drop panels can be formed Joint that creates lines of weakness so that cracking by omitting the dome form in selected areas. that may result from tensile stress occurs along predetermined lines. Type of Recommended Floor System Load One-way slab Light to One-Way Slab A concrete slab of uniform thickness reinforced in medium (6-8’) 1830-5490 mm one direction and cast integrally with parallel Light to One-Way Joist Slab supporting beams. One-way slabs are suitable only medium (15’ – 36’) 4000 – 10 000 mm for relatively short spans. The reinforcement in the Medium Two-Way Slab & Beam slab runs in one direction only, from beam to beam. to heavy (15’ – 40’) 4.5 – 12 meters Maximum spacing of the main reinforcing bars Heavy Two-Way Waffle Slab should not exceed 3 times the thickness of slab nor (24’ – 54’) 7 – 16 meters 450 mm while the maximum spacing of Light Two-Way Flat Slab temperature bars is five times the slab thickness (20’ – 40’) 6 – 12 meters not more than 450 mm. Light to Two-Way Flat Plate Min. main reinforcing bars = 12 mm Ø medium (12’ – 24’) 3.6 – 7 meters Min. Temperature bars = 10 mm Ø Max. spacing of main bars not > than 3 times thickness of slab or 450 mm Precast Concrete Slabs Max. spacing of temperature bars not < 5 times A concrete slab member or product that is cast and thickness of slab or 450 mm cured in a place other than where it is to be Steel Covering = 20 mm installed in a structure. Clear distance from center of reinforcing bars to the bottom of slab = 25 mm Solid Flat Slab Temperature bars: A precast, pre-stressed concrete plank suitable for As = 0.002 bt for Grade 300 (fy = 300 MPa) short spans and uniformly distributed floor and As = 0.0018 bt for Grade 400 (fy = 400 MPa) roof loads. Minimum Thickness of One Way Slab Simply Supported = L/20 Hollow-core Slab One end continuous = L/24 A precast, pre-stressed concrete plank internally Both ends continuous = L/28 cored to reduce dead weight. Hollow-core slabs are Cantilevered = L/10 suitable for medium to long spans and uniformly When S/L < 0.5, it is one way slab, where: S – distributed floor and roof loads. shorter span Single Tee Two-way Slab A precast, pre-stressed concrete slab having a A concrete slab of uniform thickness reinforced in broad, T-shaped section two directions and cast integrally with supporting edge beams or bearing walls on four sides. Two- Double Tee way slabs are economical for medium spans with A precast, pre-stressed concrete slab having two intermediate to heavy loads. stems and a broad cross section resembling the capital letters TT Acknowledgement: Arch. Raffy Cueva Alli 6 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Inverted Tee Foundation Engineering applies the knowledge of A precast, pre-stressed ledger beam having a cross soil mechanics, rock mechanics, geology and section resembling an inverted capital T structural engineering to the design and construction of foundation for buildings and other L-beam structures. A precast, pre-stressed ledger beam having a cross section resembling the capital letter L Shallow Foundation A foundation system type, which is employed when Ledger Beam stable soil of adequate bearing capacity occurs A reinforced concrete beam having projecting relatively near to the ground surface, they are ledges for receiving the ends of joists or slabs placed directly below the lowest part of the substructure and transfer building loads directly to Notes on Concrete Slabs the supporting soil by vertical pressure. 1. All slab reinforcement shall be 0.02 m clear from the bottom and 0.015 clear from the top of Deep Foundation slab, unless otherwise indicated or stated in A foundation system type employed when the soil code. underlying a foundation is unstable to transfer 2. In two-way slabs, the bars along the short span building loads. To a more appropriate bearing shall be at the lower layer for bottom bars, and stratum of rock or dense sand and gravel well at upper layer for top bars so that the bars below the superstructure. along the shorter span shall have the bigger effective depth, unless otherwise detailed or Footing noted due to the continuity of bars adjoining That part of the foundation bearing directly upon spans. the supporting soil, set below the natural grade line 3. In two-slabs, if the top reinforcement over a and enlarged to distribute its load over a greater common support of two adjacent spans are area. different, the smaller spacing shall be followed at that common support. Tie Beam, Footing Tie Beam, Grade Beam 4. Slab reinforcement shall rest on the A reinforced concrete beam distributing the reinforcement of the supporting beams. horizontal forces from an eccentrically loaded pile 5. Bars shall be spliced only where indicated on cap or spread footing to other pile caps or footings; details. Straight continuous bars in slabs may a reinforced concrete beam supporting a be spliced (lapped or welded) at supports for superstructure at a near a ground level and bottom bars and at mid-span for top bars. transferring the load to isolated footings, piers, or piles. Notes on Concrete Walls 1. All walls to be reinforced according to the Superstructure schedule provided in the working That part of a building or structure, which is above drawing shall be observed unless the level of the adjoining ground or the level of the otherwise specified or indicated on foundation drawings. 2. Reinforcing bars shall be 0.03 m. clear Substructure from the face of the wall except in 0.10 m The underlying structure forming the foundation of wall where they shall be at the center, a building or other construction. unless otherwise detailed. Substratum Something that underlies or serves as a base or Schedule or Wall Reinforcement foundation Wall Vertical Horizontal Remarks Thickness Soil Pressure, Contact Pressure 0.10 m. 10 mm at 10 mm at At center, hor. The actual pressure developed between the footing 0.30 m. 0.30 m. Staggered and the supporting soil mass, equal to the quotient 0.15 m. 10 mm at 10 mm at Both faces, vert. of the magnitude of the forces and the area of 0.30 m. 0.30 m. Outside contact. 0.20 m. 10 mm at 10 mm at Both faces, vert. 0.30 m. 0.25 m. Outside Passive Soil Pressure 0.25m 12 mm at 10 mm at Both faces, hor. The horizontal component of resistance developed 0.30 m. 0.25 m. Outside by a soil mass against the horizontal movement of a 0.30 12 mm at 12 mm at Both faces, hor. vertical structure through the soil. It occurs usually 0.30 m. 0.30 m. Outside at the side of retaining walls between the walls and 0.35 12 mm at 12 mm at Both faces, hor. the surrounding soil. 0.30 m. 0.30 m. Outside 0.40 12 mm at 12 mm at Both faces, hor. Active Soil Pressure 0.30 m. 0.25 m. Outside The horizontal component of pressure that a soil 0.45 16 mm at 12 mm at Both faces, hor. mass exerts on a vertical retaining wall. 0.30 m. 0.25 m. Outside 0.50 16 mm at 16 mm at Both faces, hor. Allowable Bearing Pressure, Allowable Bearing 0.30 m. 0.30 m. Outside Capacity, Allowable Soil Pressure The maximum unit pressure of a foundation is permitted to impose vertically or laterally on a FOUNDATION supporting soil mass. The lowest division of a building, its substructure, or other construction partly or wholly below the Base Course surface of the ground; designed to support and A layer of course granular materials placed and anchor the superstructure above and directly to compacted on undisturbed soil prepared fill to the earth; That part of the structure that supports prevent the capillary rise of moisture to a concrete the weight of the structure and transmits the load ground slab. to underlying soil or rock. Acknowledgement: Arch. Raffy Cueva Alli 7 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Consolidation underground water pump where the pipe is The gradual reduction in the volume of a soil mass cleaned by wash pipe and water. resulting from the application of a sustained load and an increase in compressive stress Hollow Stem Auger Boring Method A truck mounted driving rig turns the auger to a Primary Consolidation depth of more than 60 meters using continuous A reduction volume of a soil mass under the action flights of auger with a hollow stem where samples of a sustained load, due chiefly to a squeezing out of soil can be retrieved. It has an auger with sizes of water from the voids within the mass and a ranging from 60 mm to 80 mm diameter. transfer of the load from the soil water to the soil solids. Also called Primary Compression. Rotary Drilling Employed as one of the most efficient and Secondary Consolidation convenient method of soil sample retrieval method A reduction in volume of a soil mass under the and used for soil structure characterized by high action of a sustained load, due chiefly to the resistant materials such as rocks, clay as well as adjustment of the internal structure of the soil sand. Rotary boring diameter ranges from 50 mm mass after most of the load has been transferred to 200 mm. from the soil water to soil solids. Percussion Drilling Method Settlement Sometimes called Cable Tool Drilling Method, used The gradual subsiding of the structure as the soil when boring or auger method is not possible due to beneath its foundation consolidates under loading. difficulty in penetration of soil especially hard soil strata Differential Settlement The relative movement of parts of a structure Penetrometer caused by uneven settlement underlying soil or This is a device used to investigate the consistency failure of its foundation of cohesive deposit or relative density of cohesion less strata without the necessity of drilling and obtaining samples. Static penetration is Allowable Bearing Capacity of Various Solids characterized by consistent and uniform force or Soil Pounds Kgs. per Kilo- Tons pressure application and Dynamic penetration Classification per sq.ft. sqm. pascal per when driven into the soil. (psf) (Kpa) sq.ft. Standard penetration test is done by dropping a 60 Alluvial soil 1,000 4,891 54 0.5 kg. hammer into a drill hole from a height of 700 Soft clay 2,000 9,782 107 1 mm, the number of blows to make a penetration of Firm clay 4,000 19,564 215 2 300 mm is regarded as the penetration resistance. Wet sand 4,000 19,564 215 2 Sand & clay 4,000 19,564 215 2 Dutch Cone Penetration Method mixed A 60 degree cone with a base area of 100 sq. mm is Firm dry sand 6,000 29,345 322 3 used in this method. This is attached to the tip of a Coarse dry 8,000 39,128 430 4 rod and protected by a casing. The cone is pushed sand by the rod into the ground; the cone is slightly Gravel 12,000 58,690 644 6 larger than the pipe in order to minimize friction Gravel & sand 16,000 78,256 860 8 between the tool and the surrounding soil. well cemented Hardpan or 20,000 97,818 1,073 10 Vane Shear Test hard shale The vane device for shear testing of clay soil in Medium rock 40,000 195,636 2,681 25 place consists of four vertical rectangular blades at Rock under 50,000 244,545 2,681 25 right angles to vertical shaft. The vane is then caissons pushed into the soil and twisted until the soil is Hard rock 160,000 782,545 8,580 80 ruptured in a cylindrical form; shear strength is computed from the maximum moment needed to Soil Test rupture the soil and thereby obtaining soil sample. Foundation design is primarily based on the result of subsurface investigation. The technical Standard Load Test personnel have to make a reasonably accurate The following is an outline of the load test conception of the physical properties and procedure as follows; arrangement of this underlying soil. 1. Dug to the depth of the soil to be tested usually at the proposed footing level. Types of Soil Testing and Investigation Methods 2. The pit width should be at least five times the load plate width. Auger Boring Method 3. The square load plate with a general dimension An auger is used for this purpose where a hole is of 300 mm x 600 mm is set on a leveled bottom bored on the ground. Two types of auger may be of the pit. used, the Helical or Post Hole Auger. Portable 4. Load on top of the plate must be placed on the helical augers are available from 80 to 300 mm. In pit bed and a platform loaded with concrete diameter and used for making deeper holes blocks or bags of cement on top must be provided. Wash Boring Method This method employs the use of a piece of metal General Guidelines in Foundation Systems Design tube 50 mm to 100 mm in diameter, used to bore 1. Depth must be adequate to avoid lateral hole with depths ranging from 1.50 m to 3.0 m. The expulsion of material from beneath the tube or casing is cleared of the soil sample by foundation, particularly footings and mats. chopping bit to the lower portion of the wash pipe 2. Depth must be below temperature volume by means of a high velocity pump to rinse the changes or within the zone of active organic fragments of the soil through the annular space materials. between the tube and the wash pipe. This method 3. System must be safe against overturning, is similar to the process of installing an rotation, sliding or soil rupture (shear strength failure). Acknowledgement: Arch. Raffy Cueva Alli 8 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 4. System must be safe against corrosion or A reinforced concrete footing connected by a tie deterioration due to harmful materials present beam to another footing in order to balance an in the soil. asymmetrically imposed load, as at the perimeter 5. System should adequate to sustain some of a building site. changes in later site or construction geometry or be easily modified should later changes be Mat Foundation major in scope. A thick, slab-like heavily reinforced concrete 6. The foundation should be economical in terms footing supporting a number of columns or an of the methods of installation or construction. entire building. 7. Total earth movements (generally settlements) and differential movements should he tolerable Ribbed Mat for the foundation element and / or any A mat foundation reinforced by a grid of ribs above superstructure elements. or below the slab. Cellular Mat Types of Footing and Foundation Systems A composite structure of reinforced concrete slabs and basement walls serving as a mat foundation. Isolated Footing A single spread footing supporting a freestanding Raft Foundation column or pier. A mat providing a footing on yielding soil, usually for an entire building, placed so that the weight of Spread Footing the displaced soil exceeds the weight of the A concrete footing extended laterally to distribute construction. the foundation load over a wide enough area that the allowable bearing capacity of supporting soil is Grillage/Grid Foundation not exceeded. A framework of crossing beam for spreading heavy loads over large areas Square Block Footing Mid-Footing Floating Foundation Corner Footing A foundation used in yielding soil, having for its Edge Footing footing a raft placed deep enough that the weight of excavated soil is equal to or greater than the weight Square Sloped Footing of the construction supported. A type of isolated footing having inclined top, sloping towards the edges. Pile Foundation A system of piles, pile caps, and tie beams for Stepped Footing transferring building loads down to a suitable A type of footing that changes levels in stages to bearing stratum, used especially when the soul accommodate a sloping grade and maintain the mass directly below the construction is not suitable required depth at all points around a building with for the direct bearing of footings. the center having the thickest part of the building. Pile Cap Rectangular Footing A footing-like member, which joins the head of a A footing, rectangular in plan, and supporting load cluster of piles in order to distribute the load from of unequal magnitudes in both axes a column or grade beam equally among the piles Combined Footing Precast Socket Foundation A reinforced concrete footing for a perimeter A type of precast footing provided with a socket to column or foundation wall extended to support an receive a precast column. interior column load. Wall Footing Rectangular Combined Footing A continuous type of footing intended to support as A type of combined footing rectangular in plan and well as transmit the load imposed by the wall supporting two columns. Column loads are directly to the ground. assumed to be of the same magnitude. Trapezoidal Combined Footing PILE FOUNDATION Column loads on this type of footing are assumed A type of foundation system used when foundation to be of unequal magnitude. bed is too weak to support the raft or mat or any other type of footing; used to transfer excess load Footing Tie Beam to a greater depth and stratum having suitable A type of beam-like footing placed underneath the foundation ground in order to transmit and provide additional rigidity to two or more columns. Pile A long slender column of wood, steel, or reinforced Grade Beam concrete, driven or hammered vertically into the Reinforced concrete beam supporting a bearing earth to form a part of a foundation system. wall at or near the ground level; and transferring the load to isolated footings, piers or piles. End bearing Pile A pile depending principally on the bearing Continuous Footing resistance of soil or rock beneath its foot for A reinforced concrete footing extended to support support. The surrounding soil mass provides a a row of columns. degree of lateral stability for the long compression member. Also called Point-bearing Pile. Strip Footing The continuous spread footing of a foundation wall. Friction Pile A pile that depends principally in the frictional Strap/Cantilever/Connected Footing resistance of surrounding earth for support Acknowledgement: Arch. Raffy Cueva Alli 9 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Kinds of Piles Composite Pile Wood Pile Timber Piles H-Section Pile Log driven usually as a friction pile, often filled with a steel shoe and a drive band to prevent their Pile Driver shafts from splitting or shattering. A machine for driving piles, composed of a tall framework supporting machinery for line in H-Pile position before driving, a hammer and vertical rails A steel H-section, sometimes encased in concrete to for guiding the hammer. a point below the water table to prevent corrosion. Pipe Pile Types of Pile Drivers Heavy steel pipe driven with the lower end either open or closed by a heavy steel plate or point and Drop Hammer filled with concrete. A type of pile driver which is raised by means of a rope and then allowed to be dropped. Any drop Precast Concrete Pile hammer permitted shall weigh not less than one- Has a round, square or polygonal cross section and half of the pile to be driven. Gravity hammer should sometimes an open core; often pre-stressed. weigh not less than 200 pounds. Heights of all hammers shall not be more than 6 meters. Cased Pile Pile constructed by driving a steel pipe or casing Steam Pile Hammer into the ground until it meets the required A type of pile driver that is automatically raised resistance and then filling it with concrete. and dropped a short distance by the action of the steam cylinder and the piston supported in a frame, Uncased Pile which follows the pile. Pile constructed by driving a concrete plug into the ground along with a steel casing until it meets the required resistance, and then ramming concrete Types of Steam Hammer into the place as the casing is withdrawn. 1. Single Acting Steam Hammer The steam is applied to raise the striking part of Classification of Piles According to Use the hammer, then allowed to fall by gravity. The force of the blow depends on the length of the Bearing Pile stroke and the movable weight. The number of Used in foundation construction and carries blows per minute depends on the steam superimposed loads. pressure. 2. Double Acting Steam Hammer Batter Pile The steam pressure raises the hammer and also Driven at an indication to resist forces that are not reinforces the action of gravity during descent. vertical. Double acting hammers are more compact, lighter and operates with rapidity. Guide Pile Used in cofferdam construction to support the Measures to be taken in driving piles horizontal wall that in turn supports vertical sheet 1. The butt of the pile is cut off square so that the piling impact of the hammer may be distributed uniformly over the surface. Fender Pile 2. Use rings or pile caps to protect the head of a Driven at wharves or in front of a large masonry timber pile from brooming and splitting. structure to protect them from sudden blows. 3. To facilitate driving the pile true to line or position, the foot should always be cut off Sheet Pile perpendicular to its axis. Used to resist lateral pressure of the earth and to 4. The timber should be protected by using a form a wall that is intended to be watertight; it metal shoe to prevent the pile from splitting consists of timber, steel or precast concrete planks upon striking an obstruction. driven vertically side-by-side to retain earth and 5. Use steam hammer as much as possible instead prevent water from seeping into an excavation. of a drop hammer to reduce loss of energy, brooming, and splitting. Soldier Pile 6. Use a water jet whenever applicable and make A H-section sheet pile driven vertically into the an adequate soil exploration of the ground to be ground to support horizontal lagging penetrated before actual driving. Lagging refers to the heavy timber planks joined Pier together side-by-side to retain the face of an A cast-in-place concrete foundation formed by excavation. boring with a large auger or excavating by hand a shaft in the earth to a suitable bearing stratum and Pile Eccentricity is the deviation of the pile from its filling the shaft with concrete. It also refers to a plan location or from the vertical, which may result large cross-sectional dimension, each capable of in a reduction of its allowable load. transmitting the entire load as single column down to a stable stratum. Types of Piles Cast-in-Place Pile Caisson Tapered Pile – Standard (Raymond) A pier, especially when the boring is 610mm (2ft) Taper Fluted Pile (Union) or larger in diameter to permit inspection of the Button Bottom Pile (Western) bottom. Cased Concrete Pile (McArthur) Uncased Straight Shaft (McArthur and Socketed Caisson Western) A caisson that is drilled into a stratum of solid rock Simplex Pile rather than belled Precast Pile Acknowledgement: Arch. Raffy Cueva Alli 10 Ar. Joey F. Saguindan Reference: A Visual Dictionary of Architecture 2nd Edition (Francis D.K. Ching, 2012) Building Construction Illustrated 5th Edition (Francis D.K. Ching, 2014) rev_cmlorenzo17 0305  University of Santo Tomas College of Architecture Building Technology 3 Rock Caisson Caisson Larger column Poor surface and near A socketed caisson having a steel H-section core (shafts loads than for surface soils; soils of high within a concrete-filled pipe casing piles but bearing capacity (point- eliminate pile bearing on) is 8-50 meters Types of Caisson cap by using below ground surface 1. Box Caisson caissons as A watertight box made of timber and concrete, column having a bottom, but no top. extension. 2. Open Caisson A self-contained box structure made of timber, Retaining Permanent Any type of soil, but a metal and concrete. walls, bridge retaining specified zone in back of 3. Pneumatic Caisson abutments structure wall usually of controlled A type of caisson having an opening at the backfill. bottom and closed at the top or it may be an Sheet-pile Temporary Any soil: waterfront inverted box into which compressed air is Structures retaining structures require special introduced to keep the water and mud from structures as alloy or corrosion protection. coming into the box enclosure and which forms excavations, Cofferdams require control part of the integral part of the foundation. waterfront of fill material. structures, Cofferdam cofferdams. A temporary enclosure in a river, lake, etc., to keep water from the enclosed area prior to the construction of a permanent structure/s EXCAVATION Common Types of Cofferdams: The digging and removal of earth from its natural 1. Cantilever Sheet Piles position, or the cavity resulting from such removal. 2. Braced Cofferdam 3. Earth Embankment Minor Excavation 4. Double Wall Cofferdam Excavation characterized as having independent 5. Cellular Cofferdam and hollow block wall footing were the digging of Diaphragm Type the soil for the footing extend to depth from.0 to Cloverleaf Type 5.0 meters and about 0.5 meter for wall footing. Modified Type Major Excavation Foundation System Selection An excavation, which requires wide or total Foundation Use or Applicable Soil Condition extraction of the soil System Application Type Spread, Individual Any condition where bearing Shoring Footing, columns, capacity is adequate for The process of providing temporary supports to Wall walls, bridge applied load. May be used the structure or ground during excavation Footings piers on single stratum: firm layer over soft layer or soft layer Underpinning over firm layer. Check The process of rebuilding, strengthening or immediate differential and stabilizing the foundation of an existing building construction consolidation settlements. Tieback These consist of steel cables or tendons that re Mat Same as Generally soil bearing value inserted into holes pre-drilled through the sheet Foundation spread and is less than for spread piling and into the rock or a suitable stratum of soil, wall footings. footings; over one-half area grouted under pressure to anchor them to the rock Very heavy of building covered by column loads. individual footings. Check soil, and post-tensioned with a hydraulic jack. Usually settlements. reduces Foundation Wall differential Part of the foundation system, which provides settlements support for the superstructure above and enclose a and total basement or crawl space partly or wholly below settlements grade; it must be designed and constructed to resist active earth pressure and anchor the Pile superstructure against the wind and seismic forces. Foundation Slurry Wall A concrete wall cast in a trench to serve as sheeting Floating in groups (at Poor surfaces and near and often used as a permanent foundation wall. least 2) to surface soils. Soils of high carry heavy bearing capacity 20-50 Damp-proofing column, wall meters below basement or A method of foundation system protection applied loads; requires ground surface, but by to a foundation wall when a subsoil conditions pile cap distributing load along pile indicate that hydrostatic pressure from the shaft soil strength is groundwater table will not occur. adequate. Corrosive soils may require use of timber or concrete pile. FORMWORKS Bearing in groups (at Poor surface and near A system of temporary boarding, sheathing or pans least 2) to surface soils; soils of high used to produce the desired shape and size of carry heavy bearing capacity (point- concrete mass. Forms are generally used in column, wall bearing on) is 8-50 meters concrete construction since concrete is formable loads; requires below ground surface and assumes the shape of the enclosing material. pile cap Forms should be watertight, rigid and strong enough to sustain weight and pressure of concrete Acknowledgement: Arch. Raffy Cueva Alli 11 Ar. Joey F. Saguindan Reference: A Visual