CANTILEVER SLAB DESIGN EXAMPLE PDF



Cantilever Slab Design Example Pdf

CON4332 REINFORCED CONCRETE DESIGN VTC. Combined footing design, foundation design, corbel design, truss analysis and design examples can be found this site. Structural Engineering: Cantilever Slab Design skip to main skip to sidebar, ACI 318M-11 RC Bracket and Corbel Design_v0.03_2017-04-10.xlsx. Short Description: Submitted By: m_ali_abushady Submitted On: 16 Oct 2017 Downloads: 34 Rating: Total Votes:6. ACI 318M-11 Slab Punching stress using RamConcept & calculate of punching shear reinforcement. Short Description: Submitted By: m_ali_abushady Submitted On: 16 Oct 2017 Downloads: 39 Rating: Total Votes:2. ACI ….

This is a typical reinforced concrete cantilever slab

Reinforced Concrete Design to BS8110 Structural Design 1. Design of Slab (Examples and Tutorials) by Sharifah Maszura Syed Mohsin Example 2: Continuous one way slab Figure 1 shows a clear area of 12 m x 8.5 m for a hall construction in a school. The slab is supported on beams of size 225 x 500 mm spaced at 4.0 m centers. The slab thickness is to be designed as 150 mm. Given, 06/11/2009В В· This feature is not available right now. Please try again later..

Example Design a cantilever projecting out from a room slab extending 1.0m and to be used as balcony (LL = 300 kg/m2). To design any structure, and not just a cantilever slab, here is the general procedure: 1. Identify the geometry of the structure - such as span, support constraints, material properties of which the structure is made, cross section shape and size...

Example 2: Design the roof slab, beam and column of house given in figure 1. Concrete compressive strength (f c ′) = 3 ksi. Steel yield strength (f y ) = 40 ksi. Of these walls, only the cantilever retaining walls and the bridge abutments are mostly used at present due to their great economics. 8.3 DESIGN CONSIDERATIONS 8.3.1 Definitions of Terms Definitions of retaining wall parts are shown in Fig.(8.2) as:- (i) the base slab constitutes the slab…

UNRESTRAINED BEAM DESIGN-II Table 3 Effective length for Cantilever Beams (Table 8.4 of New IS: 800, Effective Length, L lt, for Cantilever of Length L) (Section 8.3.3) Restraint condition Loading conditions At Support At tip Normal destabilizing a) Continuous, with lateral restraint to top flange 1) Free 2) Lateral restraint to top flange of the slab in the longitudinal direction. Since the step is not rectangular, an equivalent rectangular section can be used with an average height equals to cos 2 t R havg = + a Example (10.1): Design a straight flight staircase in a residential building that is supported on reinforced

Of these walls, only the cantilever retaining walls and the bridge abutments are mostly used at present due to their great economics. 8.3 DESIGN CONSIDERATIONS 8.3.1 Definitions of Terms Definitions of retaining wall parts are shown in Fig.(8.2) as:- (i) the base slab constitutes the slab… Full Beam Design Example CEE 3150 – Reinforced Concrete Design – Fall 2003 Design the flexural (including cutoffs) and shear reinforcement for a typical interior span of a six span continuous beam with center-to-center spacing of 20 ft. Assume the supports are 12 inches wide. Check that deflection (excessive deflections will cause

8 CHAPTER 8: DESIGN OF ONE-WAY SLABS 8.1 Introduction A slab is structural element whose thickness is small compared to its own length and width. Slabs are usually used in floor and roof construction. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types; one-way and two-way. One-way slabs: When the ratio of the longer to the … Engineering Books Excel Sheets Design of Cantilever Slab Spreadsheet. Design of Cantilever Slab Spreadsheet 10:24 PM Excel Sheets. Design of Cantilever Slab Spreadsheet . Cantilever slabs are a typical one way slabs. They are projections from wall face of lintel beams or floor slabs. Even while designing they are considered as one-slabs with cantilever fixed or continuous at supports. The

EXAMPLE 6 - DECK DESIGN, INCLUDING COLLISION ON A TYPE 7 & TYPE 10M BARRIER 6 2019 Where: Flexural cracking variability factor Оі1 = 1.60 (non-segmental brg.) Example Design a cantilever projecting out from a room slab extending 1.0m and to be used as balcony (LL = 300 kg/m2).

Tributary Areas University of Kentucky College of. Combined footing design, foundation design, corbel design, truss analysis and design examples can be found this site. Structural Engineering: Cantilever Slab Design skip to main skip to sidebar, Design and detailing of a cantilever slab is the same as that of a cantilever beam (Section 3.3) of unit width. Temperature and shrinkage reinforcement is provided along the direction perpendicular to the span. This is illustrated through the following example. Example 4.1. Design the cantilever slab of a bus stand shown in Figure 4.1..

Full Beam Design Example

cantilever slab design example pdf

Structural Engineering Cantilever Slab Design. DEFLECTION OF CONCRETE FLOOR SYSTEMS FOR SERVICEABILITY1 excess of 1/250, and for cantilevers in excess of 1/125. The out-of-level condition of a floor system can be controlled through camber at the time of construction, upon estimating the long-term deflection. Deflection Limits to Mitigate Damage to Non-structural Construction It is important to note that ACI [ACI 318, 2008] does …, UNRESTRAINED BEAM DESIGN-II Table 3 Effective length for Cantilever Beams (Table 8.4 of New IS: 800, Effective Length, L lt, for Cantilever of Length L) (Section 8.3.3) Restraint condition Loading conditions At Support At tip Normal destabilizing a) Continuous, with lateral restraint to top flange 1) Free 2) Lateral restraint to top flange.

Design of Cantilever Slab Spreadsheet Engineering Books

cantilever slab design example pdf

Design Aid 6 Beam Design Formulas with Shear and Moment. Nov 2, 2019- This is a typical reinforced concrete cantilever slab reinforcement detail with a constant slab width throught the extension and the adjucent slab. Cantilever slab supported on a reinf. concrete beam with top and bottom reinforcement as well as middle torsion reinforcement. Slab reinforced with top U-shaped 'hairpin' top https://en.m.wikipedia.org/wiki/Cantilever_bridge Full Beam Design Example CEE 3150 – Reinforced Concrete Design – Fall 2003 Design the flexural (including cutoffs) and shear reinforcement for a typical interior span of a six span continuous beam with center-to-center spacing of 20 ft. Assume the supports are 12 inches wide. Check that deflection (excessive deflections will cause.

cantilever slab design example pdf


Slabs and Flat Slabs Lecture 5 19 th October 2016 Contents –Lecture 5 • Designing for shear in slabs -including punching shear • Detailing –Solid slabs • Flat Slab Design –includes flexure worked example • Exercise -Punching shear of the slab in the longitudinal direction. Since the step is not rectangular, an equivalent rectangular section can be used with an average height equals to cos 2 t R havg = + a Example (10.1): Design a straight flight staircase in a residential building that is supported on reinforced

of the slab in the longitudinal direction. Since the step is not rectangular, an equivalent rectangular section can be used with an average height equals to cos 2 t R havg = + a Example (10.1): Design a straight flight staircase in a residential building that is supported on reinforced This Manual provides four design examples illustrating the application of the strut-and-tie method for a variety of structural configurations, including a simply-supported deep beam, a cantilever bent cap, an inverted-tee moment frame straddle bent cap, and a drilled shaft footing. Each design example is

8 CHAPTER 8: DESIGN OF ONE-WAY SLABS 8.1 Introduction A slab is structural element whose thickness is small compared to its own length and width. Slabs are usually used in floor and roof construction. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types; one-way and two-way. One-way slabs: When the ratio of the longer to the … cantilever one-way slabs: The landing may be modeled as a slab (one-way or two-way) with two continuous and two discontinuous sides. The thickness of the landing should be determined by the conditions of either one-way or two-slab with the given support conditions. The design bending moment of this one-way/two-way slab should be determined and reinforcements should be calculated (as we

Example 2: Design the roof slab, beam and column of house given in figure 1. Concrete compressive strength (f c ′) = 3 ksi. Steel yield strength (f y ) = 40 ksi. A square tied column supports a dead load of 400 kips and live load of 200 kips. Design the column assuming a steel ratio of 4%, f'c = 5 ksi, and fy = 60 ksi. Also, …

Design Envelopes for Cantilever Slabs to Resist Blast Loads . Conference Paper (PDF Available) · December 2011 with 1,064 Reads How we measure 'reads' … Design Envelopes for Cantilever Slabs to Resist Blast Loads . Conference Paper (PDF Available) · December 2011 with 1,064 Reads How we measure 'reads' …

pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever To design any structure, and not just a cantilever slab, here is the general procedure: 1. Identify the geometry of the structure - such as span, support constraints, material properties of which the structure is made, cross section shape and size...

Department of Mechanics, Materials and Structures English courses Reinforced Concrete Structures Code: BMEEPSTK601 Lecture no. 10: FLAT SLABS . Reinforced Concrete 2012 lecture 10/2 Content: 1. Introduction, definitions 2. The effective span 3. Methods of analysis 4. The method of substitutive strips 5. Moment steel distribution above columns 6. System of welded mesh reinforcement 7. Perimeter pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever

How can we design a cantilever slab? Quora

cantilever slab design example pdf

DEFLECTION OF CONCRETE FLOOR SYSTEMS FOR. Full Beam Design Example CEE 3150 – Reinforced Concrete Design – Fall 2003 Design the flexural (including cutoffs) and shear reinforcement for a typical interior span of a six span continuous beam with center-to-center spacing of 20 ft. Assume the supports are 12 inches wide. Check that deflection (excessive deflections will cause, Design Envelopes for Cantilever Slabs to Resist Blast Loads . Conference Paper (PDF Available) · December 2011 with 1,064 Reads How we measure 'reads' ….

Reinforced Concrete Cantilever Beam YouTube

Design Aid 6 Beam Design Formulas with Shear and Moment. pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever, SUPPLEMENT: DESIGN VALUES FOR WOOD CONSTRUCTION ASD/LRFD American W ood Council BEAM DESIGN FORMULAS WITH SHEAR AND MOMENT DIAGRAMS American Forest & Paper Association w R V V 2 2 Shear M max Moment x DESIGN AID No. 6. AMERICAN WOOD COUNCIL The American Wood Council (AWC) is part of the wood products group of the American Forest & Paper Association ….

This Manual provides four design examples illustrating the application of the strut-and-tie method for a variety of structural configurations, including a simply-supported deep beam, a cantilever bent cap, an inverted-tee moment frame straddle bent cap, and a drilled shaft footing. Each design example is CE 437/537, Fall 2002 Slab-On-Grade Example -Design Info 1 / 8 Design the thickness for a slab-on-grade concrete slab in a warehouse. Design the minimum slab thickness to support a fork lift (specified below) and storage racks (specified below) throughout. Design a thickened slab to support the columns and

slab for flexure Section in Example Design wingwall Start Check the flexure and shear resistance of the backwall. Design pile cap reinforcement. Check flexure and shear. Design Step 7.1.1 Design Step 7.1.2 Design Step 7.1.3.1 Design Step 7.1.4 Design Step 7.1.4.1 Design Step 7.1.5 Design Step 7.1.6 Archived. Design Step 3 – Design Flowcharts Prestressed Concrete Bridge Design Example Task Element Design & Detailing • Three elements of retaining wall: Stem, Toe slab & Heel slab are designed as cantilever slab • Stem: Designed to resist moment caused by force f H k ( f = load combination 1) • Toe Slab: Net pressure is obtained by deducting the weight of concrete in the toe slab …

CE 433, Fall 2006 Slab Design Example 1 / 6 Design a one-way slab for an exterior bay of a multi-story office building using the information specified below. Plan View of Floor System Assume partitions will not be damaged by deflections. Round slab thickness up to the nearest ¼”. wSD = 20 psf wLL = 80 psf f'c = 4000 psi fy = 60,000 psi span In reinforced concrete construction, slabs are used to flat, useful surfaces.. A reinforced slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so.Analysis and Design …

of the slab in the longitudinal direction. Since the step is not rectangular, an equivalent rectangular section can be used with an average height equals to cos 2 t R havg = + a Example (10.1): Design a straight flight staircase in a residential building that is supported on reinforced UNRESTRAINED BEAM DESIGN-II Table 3 Effective length for Cantilever Beams (Table 8.4 of New IS: 800, Effective Length, L lt, for Cantilever of Length L) (Section 8.3.3) Restraint condition Loading conditions At Support At tip Normal destabilizing a) Continuous, with lateral restraint to top flange 1) Free 2) Lateral restraint to top flange

EXAMPLE 6 - DECK DESIGN, INCLUDING COLLISION ON A TYPE 7 & TYPE 10M BARRIER 6 2019 Where: Flexural cracking variability factor Оі1 = 1.60 (non-segmental brg.) 02/09/2011В В· Design of Reinforced Concrete Beams 43 2.1 ANALYSIS OF BEAMS 2.1.1 Effective spans SK 212 Continuous beam. SK 2/3 Cantilever beam. SK 2/1 Simply supported beam. Simply supported or encastrГ© Continuous le = 10 le = smaller of (I + d) or 10 Cantilever where 10 = centre-to-centre distance between supports effective span

pdf. Cantilever Slab Design . Ramjan Shehzaad Therefore, slabs may have different names depending upon its bending, support conditions and shapes. For example, a slab may be called (a) One-way simply supported rectangular slab, (b) Two-way simply supported or restrained rectangular slab, (c) Cantilever rectangular slab, (d) Fixed or simply supported circular slab, etc. One-way slab means To design any structure, and not just a cantilever slab, here is the general procedure: 1. Identify the geometry of the structure - such as span, support constraints, material properties of which the structure is made, cross section shape and size...

Element Design & Detailing • Three elements of retaining wall: Stem, Toe slab & Heel slab are designed as cantilever slab • Stem: Designed to resist moment caused by force f H k ( f = load combination 1) • Toe Slab: Net pressure is obtained by deducting the weight of concrete in the toe slab … Worked examples presented at the Workshop “Eurocode 7: Geotechnical Design” Dublin, 13-14 June, 2013 Support to the implementation, harmonization and further development of the Eurocodes

pdf. Cantilever Slab Design . Ramjan Shehzaad Therefore, slabs may have different names depending upon its bending, support conditions and shapes. For example, a slab may be called (a) One-way simply supported rectangular slab, (b) Two-way simply supported or restrained rectangular slab, (c) Cantilever rectangular slab, (d) Fixed or simply supported circular slab, etc. One-way slab means This Manual provides four design examples illustrating the application of the strut-and-tie method for a variety of structural configurations, including a simply-supported deep beam, a cantilever bent cap, an inverted-tee moment frame straddle bent cap, and a drilled shaft footing. Each design example is

Get this CAD detailed drawing of a reinforced concrete cantilever veranda slab with a parapet wall detail in dwg, dxf and pdf formats, use it in your projects and save yourself valuable time. Slab main top & bottom reinforcement, transverse reinf., cantilever hairpin … CE 437/537, Fall 2002 Slab-On-Grade Example -Design Info 1 / 8 Design the thickness for a slab-on-grade concrete slab in a warehouse. Design the minimum slab thickness to support a fork lift (specified below) and storage racks (specified below) throughout. Design a thickened slab to support the columns and

EXAMPLE 6 DECK DESIGN INCLUDING COLLISION ON A TYPE 7

cantilever slab design example pdf

Reinforced Concrete Constant Width Cantilever Slab Detail. European Commission Joint Research Centre Institute for the Protection and Security of the Citizen Contact information Address: Joint Research Centre, Via …, Example 2: Design the roof slab, beam and column of house given in figure 1. Concrete compressive strength (f c ′) = 3 ksi. Steel yield strength (f y ) = 40 ksi..

EXAMPLE 6 DECK DESIGN INCLUDING COLLISION ON A TYPE 7. CON4332 REINFORCED CONCRETE DESIGN Chapter 5 3 HD in Civil Engineering (Aug 2014) Figure 5.1 – Aspect Ratio of One-way Slab In addition to the slab supported on two or four edges as mentioned above, slab can also be supported on a single edge, i.e. cantilever slab, or directly on columns, i.e. flat slab. If the span of the slab is very large, To design any structure, and not just a cantilever slab, here is the general procedure: 1. Identify the geometry of the structure - such as span, support constraints, material properties of which the structure is made, cross section shape and size....

Cantilever Slab design PART-1 by Parag Kamlakar Pal. YouTube

cantilever slab design example pdf

Bridge Railing Deck Design Example. pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever https://en.m.wikipedia.org/wiki/Cantilever_bridge pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever.

cantilever slab design example pdf


To design any structure, and not just a cantilever slab, here is the general procedure: 1. Identify the geometry of the structure - such as span, support constraints, material properties of which the structure is made, cross section shape and size... Manual for Design and Detailings of Reinforced Concrete to Code of Practice for Structural Use of Concrete 2004 Housing Department May 2008 (Version 2.3) Acknowledgement We would like to express our greatest gratitude to Professor A.K.H. Kwan of The University of Hong Kong who has kindly and generously provided invaluable advice and information during the course of our drafting of the Manual

A square tied column supports a dead load of 400 kips and live load of 200 kips. Design the column assuming a steel ratio of 4%, f'c = 5 ksi, and fy = 60 ksi. Also, … UNRESTRAINED BEAM DESIGN-II Table 3 Effective length for Cantilever Beams (Table 8.4 of New IS: 800, Effective Length, L lt, for Cantilever of Length L) (Section 8.3.3) Restraint condition Loading conditions At Support At tip Normal destabilizing a) Continuous, with lateral restraint to top flange 1) Free 2) Lateral restraint to top flange

Design of Slab (Examples and Tutorials) by Sharifah Maszura Syed Mohsin Example 2: Continuous one way slab Figure 1 shows a clear area of 12 m x 8.5 m for a hall construction in a school. The slab is supported on beams of size 225 x 500 mm spaced at 4.0 m centers. The slab thickness is to be designed as 150 mm. Given EXAMPLE 6 - DECK DESIGN, INCLUDING COLLISION ON A TYPE 7 & TYPE 10M BARRIER 6 2019 Where: Flexural cracking variability factor Оі1 = 1.60 (non-segmental brg.)

Combined footing design, foundation design, corbel design, truss analysis and design examples can be found this site. Structural Engineering: Cantilever Slab Design skip to main skip to sidebar Example 2: Design the roof slab, beam and column of house given in figure 1. Concrete compressive strength (f c ′) = 3 ksi. Steel yield strength (f y ) = 40 ksi.

18/02/2017 · Cantilever Slab design full with detail knowledge. plz visit my website www.civilnotess.com CON4332 REINFORCED CONCRETE DESIGN Chapter 5 3 HD in Civil Engineering (Aug 2014) Figure 5.1 – Aspect Ratio of One-way Slab In addition to the slab supported on two or four edges as mentioned above, slab can also be supported on a single edge, i.e. cantilever slab, or directly on columns, i.e. flat slab. If the span of the slab is very large

EXAMPLE 6 - DECK DESIGN, INCLUDING COLLISION ON A TYPE 7 & TYPE 10M BARRIER 6 2019 Where: Flexural cracking variability factor γ1 = 1.60 (non-segmental brg.) slab for flexure Section in Example Design wingwall Start Check the flexure and shear resistance of the backwall. Design pile cap reinforcement. Check flexure and shear. Design Step 7.1.1 Design Step 7.1.2 Design Step 7.1.3.1 Design Step 7.1.4 Design Step 7.1.4.1 Design Step 7.1.5 Design Step 7.1.6 Archived. Design Step 3 – Design Flowcharts Prestressed Concrete Bridge Design Example Task

SLAB DESIGN Reading Assignment Chapter 9 of Text and, Chapter 13 of ACI318-02 Introduction ACI318 Code provides two design procedures for slab systems: 13.6.1 Direct Design Method (DDM) For slab systems with or without beams loaded only by gravity loads and having a fairly regular layout meeting the following conditions: 13.6.1.1 There must be three or more spans in each directions. 13.6.1.2 A square tied column supports a dead load of 400 kips and live load of 200 kips. Design the column assuming a steel ratio of 4%, f'c = 5 ksi, and fy = 60 ksi. Also, …

Hello everyone, I am trying to design a 2.10m x 6.42m cantilever slab (200mm thick) and the accompanying beam (section: 250x600mm, clear span: 4.60) that would Reinforced Concrete Constant Width Cantilever Slab Detail. This is a typical CAD dwg drawing of a Reinforced Concrete Constant Width Cantilever Slab Detail. Reinforcement details for the cantilever and the adjucent slab. Cantilever slab supported on a reinf. concrete beam with top and bottom reinforcement as well as middle torsion reinforcement.

cantilever one-way slabs: The landing may be modeled as a slab (one-way or two-way) with two continuous and two discontinuous sides. The thickness of the landing should be determined by the conditions of either one-way or two-slab with the given support conditions. The design bending moment of this one-way/two-way slab should be determined and reinforcements should be calculated (as we 18/02/2017В В· Cantilever Slab design full with detail knowledge. plz visit my website www.civilnotess.com

Of these walls, only the cantilever retaining walls and the bridge abutments are mostly used at present due to their great economics. 8.3 DESIGN CONSIDERATIONS 8.3.1 Definitions of Terms Definitions of retaining wall parts are shown in Fig.(8.2) as:- (i) the base slab constitutes the slab… Bridge Railing & Deck Design Example Michael H. Wenning, P.E. & Kurt Heidenreich, P.E., S.E. Bridge Railing Design. 2 Bridge Railing Design • AASHTO 17th Edition and prior – 10k Load distributed over 5’ – Applied perpendicular at top of rail Bridge Railing Design NCHRP Report published in 1993 All Railing Systems must be crash tested. 3 Bridge Railing Design Rail selection defined in

cantilever slab design example pdf

pdf. LRFD DESIGN EXAMPLE-PRECAST BALANCED CANTILEVER BRIDGE DESIG . Carlos Argote resulting in a maximum segment weight of 72.5 tons for the thin bottom slab segment and 80 tons for the thick bottom slab segment. LRFD Design Example Precast Balanced Cantilever Construction 3-2 LRFD Design Example Precast Balanced Cantilever Construction 3-3 LRFD Design Example Precast Balanced Cantilever Bridge Railing & Deck Design Example Michael H. Wenning, P.E. & Kurt Heidenreich, P.E., S.E. Bridge Railing Design. 2 Bridge Railing Design • AASHTO 17th Edition and prior – 10k Load distributed over 5’ – Applied perpendicular at top of rail Bridge Railing Design NCHRP Report published in 1993 All Railing Systems must be crash tested. 3 Bridge Railing Design Rail selection defined in