Pancyprian Mechanics & Construction cheat sheet

Equilibrium of a planar rigid body requires ΣFx = 0, ΣFy = 0, ΣM = 0 about any point; three independent equations solve three unknowns.

Moment of a force about a point: M = F·d, where d is the perpendicular distance from the point to the line of action; sign convention must be fixed before summing.

Resultant of a concurrent force system: Rx = ΣFx, Ry = ΣFy, R = √(Rx² + Ry²), direction θ = arctan(Ry/Rx) measured from the x-axis.

Centroid of a composite area: x̄ = Σ(Ai·x̄i)/ΣAi, ȳ = Σ(Ai·ȳi)/ΣAi; for a triangle the centroid lies at one-third of the height from the base.

Friction limit: impending sliding occurs when F = μs·N; kinetic friction F = μk·N applies once motion starts, with μk < μs.

Equations of motion for constant acceleration: v = u + at, s = ut + ½at², v² = u² + 2as; these apply only when a is constant.

Newton's second law for a particle: ΣF = m·a; for a rigid body in plane motion the couple equation ΣM_G = I_G·α is added.

Work-energy principle: U₁₋₂ = ΔT, where work by a constant force is F·s·cosθ and kinetic energy T = ½mv²; power P = F·v.

Axial stress σ = N/A; axial strain ε = ΔL/L; Hooke's law σ = E·ε applies within the elastic limit, with E in GPa for steel (about 200 GPa).

Elongation of an axially loaded bar: ΔL = N·L/(A·E); for stepped or varying loads sum the contributions of each segment.

Bending stress: σ = M·y/I, maximum at the extreme fibre with y = c; section modulus W = I/c gives σmax = M/W.

Second moment of area for a rectangle about its centroidal axis: I = b·h³/12; parallel axis theorem I = I_c + A·d².

Shear stress in bending: τ = V·Q/(I·b); τ is zero at the extreme fibres and maximum at the neutral axis for a rectangular section.

Deflection of a simply supported beam under central point load P: δmax = P·L³/(48·E·I) at midspan.

Euler buckling load for a pin-ended column: Pcr = π²·E·I/L²; effective length factors reduce capacity for other end conditions.

Determinacy of a plane truss: m + r = 2j for statically determinate; m + r > 2j indicates redundancy, m + r < 2j indicates instability.

Concrete characteristic strength fck is the 28-day cube strength below which no more than 5% of test results should fall; cylinder strength ≈ 0.8 × cube strength.

Concrete mix design targets water/cement ratio and exposure class; lower w/c increases strength and durability but reduces workability.

Cement types: CEM I (Portland), CEM II (Portland-composite), CEM III (blastfurnace), CEM IV (pozzolanic), CEM V (composite); sulfate-resistant and low-heat grades are selected for aggressive ground or mass pours.

Reinforcement: B500 deformed bars have characteristic yield strength 500 MPa; nominal cover is set by exposure class and fire resistance, not by bar diameter alone.

Concrete curing must retain moisture; stripping times depend on member type and achieved strength, typically verified by cube tests or maturity methods.

Masonry: mortar designation (M2.5 to M12) is chosen with unit strength; movement joints are required at intervals to accommodate thermal and moisture expansion.

Structural steel grade S275 or S355 denotes minimum yield strength in MPa; bolted connections use preloaded or bearing-type bolts per design category.

Bituminous mixtures are specified by aggregate gradation, binder grade and air voids; compaction temperature window is set by binder viscosity.

First-angle projection places the view from above below the front view; third-angle projection places it above; the projection symbol on the drawing identifies which system applies.

Scale notation 1:100 means 1 unit on the drawing equals 100 units on site; a 25 mm dimension on a 1:100 drawing represents 2.5 m.

Line hierarchy: continuous thick for visible outlines, continuous thin for dimension and projection lines, dashed for hidden edges, chain lines for centre lines and section planes.

A section drawing is identified by cutting-plane line with arrows showing viewing direction and by a section label (e.g. A-A).

Levels are annotated with a datum symbol and value in metres to three decimals, e.g. +3.450; the project datum is stated on the drawing title block.

Reinforcement drawings use bar marks with diameter, spacing and shape code; the bending schedule lists total lengths and weights per bar mark.

Drawing register and revision control: superseded drawings must be marked, and only the latest revision is valid for construction.

Levelling: height difference between two points = backsight reading − foresight reading; reduced level = known RL + backsight − foresight (height of collimation method).

Rise and fall method checks that Σbacksight − Σforesight = Σrise − Σfall = last RL − first RL.

Closed traverse angular check: sum of measured interior angles should equal (n−2)·180°; misclosure is distributed equally among the angles.

Coordinate computation from bearing and distance: ΔE = d·sinθ, ΔN = d·cosθ, with bearings measured clockwise from north.

Total station measures slope distance, then horizontal distance = slope distance × cos(vertical angle); EDM accuracy is quoted as ±(a + b ppm).

Volume by end areas: V = L·(A₁ + A₂)/2 for a prismoid segment; prismoidal formula V = L·(A₁ + 4Am + A₂)/6 is more accurate.

Setting out: right angles by 3-4-5 triangle or by theodolite; a baseline is established first and offsets are measured perpendicular to it.

Tolerance for setting out is project-specific; structural grid lines are typically checked against the design coordinates before any concrete is placed.

Electrical supply in Cyprus is 230 V single-phase, 50 Hz; three-phase distribution is 400 V between phases.

Protection: an RCD rated 30 mA is required for socket circuits and wet areas; MCBs protect against overload and short circuit and are selected to the cable current-carrying capacity.

Earthing system types (TN-S, TN-C-S, TT) determine the protective measures and the need for an earth electrode at the installation.

Plumbing: hot water distribution uses a secondary return or is kept short to limit dead legs; pressure-reducing valves are fitted where mains pressure exceeds fixture rating.

Drainage: soil and waste stacks require ventilation to prevent trap seal loss; trap seals are nominally 50 mm minimum.

HVAC sizing: heating load by fabric transmission plus ventilation; cooling load includes solar gains, internal gains and latent load, not just temperature difference.

Ventilation rates are set per occupancy and use; mechanical extract is required in kitchens and sanitary spaces without openable windows.

Fire detection and alarm systems are zoned to limit the search area; sounders must achieve the specified sound pressure level at the bedhead or in occupied rooms.

Hierarchy of control: eliminate, substitute, engineering controls, administrative controls, then personal protective equipment as the last line of defence.

Working at height is the leading cause of fatal construction accidents; collective protection (guardrails, nets) takes priority over personal fall arrest.

Excavations: support or batter sides, keep spoil back from the edge, provide ladders within 25 m of travel, and inspect after rain or any ground movement.

Scaffolding must be erected, altered and dismantled by competent persons; it is inspected before first use and at intervals not exceeding 7 days.

Site induction and task-specific briefing are required before any worker starts; visitors must be escorted and issued PPE.

Site layout: separate pedestrian and vehicle routes, locate storage and plant away from excavations, and position welfare facilities within reasonable distance of the works.

Emergency arrangements: fire points, escape routes, assembly point, first-aid provision and emergency contact numbers are displayed on site.

Lifting operations require a plan by a competent person; exclusion zones are maintained beneath suspended loads and no person may ride on a load.

Building permits: construction may not start before the planning and building permit is issued by the competent authority; deviations require a revised permit.

Cyprus building regulation references include the national seismic design provisions aligned with Eurocode 8 and the Eurocodes adopted as national standards.

Contract forms allocate risk: lump-sum contracts place quantity risk on the contractor; measurement (re-measurement) contracts pay for actual quantities executed.

Variations must be instructed in writing by the contract administrator; without a written instruction, the contractor's entitlement to payment is weak.

Time provisions: extension of time is granted for employer-risk events; liquidated damages apply for culpable delay at a stated rate per day.

Retention is typically deducted from interim payments and released in two parts - on practical completion and after the defects liability period.

Interim payment certificates are issued at stated intervals; the contractor submits an application and the certifier assesses the value of work executed.

Health and safety duties are imposed on the client, designer and contractor, who must cooperate and coordinate; the client must appoint competent persons.

Unit-rate estimating: rate = labour + material + plant + subcontract + overheads + profit, expressed per unit of measurement (m³, m², m, nr).

Labour output is expressed as hours per unit; cost = hours × hourly rate including social insurance and allowances.

Quantity take-off follows the measurement rules of the chosen standard method; items are grouped by work section and measured net unless rules state otherwise.

Preliminaries (site establishment, supervision, temporary works, insurance) are priced separately and are not distributed into unit rates.

Cash flow and cost control use earned value: CPI = EV/AC and SPI = EV/PV; a CPI below 1.0 indicates cost overrun.

Contingency is an allowance for identified but unquantified risk; it is held in the estimate and released as risk is retired.

Quality control of concrete: slump test for workability, cube tests at 7 and 28 days for strength, and cover meter checks for reinforcement position.

Inspection and test plans (ITPs) define hold points where work cannot proceed without documented verification and sign-off.

Equilibrium of a planar rigid body requires ΣFx = 0, ΣFy = 0, ΣM = 0 about any point; three independent equations solve three unknowns.

Moment of a force about a point: M = F·d, where d is the perpendicular distance from the point to the line of action; sign convention must be fixed before summing.

Resultant of a concurrent force system: Rx = ΣFx, Ry = ΣFy, R = √(Rx² + Ry²), direction θ = arctan(Ry/Rx) measured from the x-axis.

Centroid of a composite area: x̄ = Σ(Ai·x̄i)/ΣAi, ȳ = Σ(Ai·ȳi)/ΣAi; for a triangle the centroid lies at one-third of the height from the base.

Friction limit: impending sliding occurs when F = μs·N; kinetic friction F = μk·N applies once motion starts, with μk < μs.

Equations of motion for constant acceleration: v = u + at, s = ut + ½at², v² = u² + 2as; these apply only when a is constant.

Newton's second law for a particle: ΣF = m·a; for a rigid body in plane motion the couple equation ΣM_G = I_G·α is added.

Work-energy principle: U₁₋₂ = ΔT, where work by a constant force is F·s·cosθ and kinetic energy T = ½mv²; power P = F·v.

Axial stress σ = N/A; axial strain ε = ΔL/L; Hooke's law σ = E·ε applies within the elastic limit, with E in GPa for steel (about 200 GPa).

Elongation of an axially loaded bar: ΔL = N·L/(A·E); for stepped or varying loads sum the contributions of each segment.

Bending stress: σ = M·y/I, maximum at the extreme fibre with y = c; section modulus W = I/c gives σmax = M/W.

Second moment of area for a rectangle about its centroidal axis: I = b·h³/12; parallel axis theorem I = I_c + A·d².

Shear stress in bending: τ = V·Q/(I·b); τ is zero at the extreme fibres and maximum at the neutral axis for a rectangular section.

Deflection of a simply supported beam under central point load P: δmax = P·L³/(48·E·I) at midspan.

Euler buckling load for a pin-ended column: Pcr = π²·E·I/L²; effective length factors reduce capacity for other end conditions.

Determinacy of a plane truss: m + r = 2j for statically determinate; m + r > 2j indicates redundancy, m + r < 2j indicates instability.

Concrete characteristic strength fck is the 28-day cube strength below which no more than 5% of test results should fall; cylinder strength ≈ 0.8 × cube strength.

Concrete mix design targets water/cement ratio and exposure class; lower w/c increases strength and durability but reduces workability.

Cement types: CEM I (Portland), CEM II (Portland-composite), CEM III (blastfurnace), CEM IV (pozzolanic), CEM V (composite); sulfate-resistant and low-heat grades are selected for aggressive ground or mass pours.

Reinforcement: B500 deformed bars have characteristic yield strength 500 MPa; nominal cover is set by exposure class and fire resistance, not by bar diameter alone.

Concrete curing must retain moisture; stripping times depend on member type and achieved strength, typically verified by cube tests or maturity methods.

Masonry: mortar designation (M2.5 to M12) is chosen with unit strength; movement joints are required at intervals to accommodate thermal and moisture expansion.

Structural steel grade S275 or S355 denotes minimum yield strength in MPa; bolted connections use preloaded or bearing-type bolts per design category.

Bituminous mixtures are specified by aggregate gradation, binder grade and air voids; compaction temperature window is set by binder viscosity.

First-angle projection places the view from above below the front view; third-angle projection places it above; the projection symbol on the drawing identifies which system applies.

Scale notation 1:100 means 1 unit on the drawing equals 100 units on site; a 25 mm dimension on a 1:100 drawing represents 2.5 m.

Line hierarchy: continuous thick for visible outlines, continuous thin for dimension and projection lines, dashed for hidden edges, chain lines for centre lines and section planes.

A section drawing is identified by cutting-plane line with arrows showing viewing direction and by a section label (e.g. A-A).

Levels are annotated with a datum symbol and value in metres to three decimals, e.g. +3.450; the project datum is stated on the drawing title block.

Reinforcement drawings use bar marks with diameter, spacing and shape code; the bending schedule lists total lengths and weights per bar mark.

Drawing register and revision control: superseded drawings must be marked, and only the latest revision is valid for construction.

Levelling: height difference between two points = backsight reading − foresight reading; reduced level = known RL + backsight − foresight (height of collimation method).

Rise and fall method checks that Σbacksight − Σforesight = Σrise − Σfall = last RL − first RL.

Closed traverse angular check: sum of measured interior angles should equal (n−2)·180°; misclosure is distributed equally among the angles.

Coordinate computation from bearing and distance: ΔE = d·sinθ, ΔN = d·cosθ, with bearings measured clockwise from north.

Total station measures slope distance, then horizontal distance = slope distance × cos(vertical angle); EDM accuracy is quoted as ±(a + b ppm).

Volume by end areas: V = L·(A₁ + A₂)/2 for a prismoid segment; prismoidal formula V = L·(A₁ + 4Am + A₂)/6 is more accurate.

Setting out: right angles by 3-4-5 triangle or by theodolite; a baseline is established first and offsets are measured perpendicular to it.

Tolerance for setting out is project-specific; structural grid lines are typically checked against the design coordinates before any concrete is placed.

Electrical supply in Cyprus is 230 V single-phase, 50 Hz; three-phase distribution is 400 V between phases.

Protection: an RCD rated 30 mA is required for socket circuits and wet areas; MCBs protect against overload and short circuit and are selected to the cable current-carrying capacity.

Earthing system types (TN-S, TN-C-S, TT) determine the protective measures and the need for an earth electrode at the installation.

Plumbing: hot water distribution uses a secondary return or is kept short to limit dead legs; pressure-reducing valves are fitted where mains pressure exceeds fixture rating.

Drainage: soil and waste stacks require ventilation to prevent trap seal loss; trap seals are nominally 50 mm minimum.

HVAC sizing: heating load by fabric transmission plus ventilation; cooling load includes solar gains, internal gains and latent load, not just temperature difference.

Ventilation rates are set per occupancy and use; mechanical extract is required in kitchens and sanitary spaces without openable windows.

Fire detection and alarm systems are zoned to limit the search area; sounders must achieve the specified sound pressure level at the bedhead or in occupied rooms.

Hierarchy of control: eliminate, substitute, engineering controls, administrative controls, then personal protective equipment as the last line of defence.

Working at height is the leading cause of fatal construction accidents; collective protection (guardrails, nets) takes priority over personal fall arrest.

Excavations: support or batter sides, keep spoil back from the edge, provide ladders within 25 m of travel, and inspect after rain or any ground movement.

Scaffolding must be erected, altered and dismantled by competent persons; it is inspected before first use and at intervals not exceeding 7 days.

Site induction and task-specific briefing are required before any worker starts; visitors must be escorted and issued PPE.

Site layout: separate pedestrian and vehicle routes, locate storage and plant away from excavations, and position welfare facilities within reasonable distance of the works.

Emergency arrangements: fire points, escape routes, assembly point, first-aid provision and emergency contact numbers are displayed on site.

Lifting operations require a plan by a competent person; exclusion zones are maintained beneath suspended loads and no person may ride on a load.

Building permits: construction may not start before the planning and building permit is issued by the competent authority; deviations require a revised permit.

Cyprus building regulation references include the national seismic design provisions aligned with Eurocode 8 and the Eurocodes adopted as national standards.

Contract forms allocate risk: lump-sum contracts place quantity risk on the contractor; measurement (re-measurement) contracts pay for actual quantities executed.

Variations must be instructed in writing by the contract administrator; without a written instruction, the contractor's entitlement to payment is weak.

Time provisions: extension of time is granted for employer-risk events; liquidated damages apply for culpable delay at a stated rate per day.

Retention is typically deducted from interim payments and released in two parts - on practical completion and after the defects liability period.

Interim payment certificates are issued at stated intervals; the contractor submits an application and the certifier assesses the value of work executed.

Health and safety duties are imposed on the client, designer and contractor, who must cooperate and coordinate; the client must appoint competent persons.

Unit-rate estimating: rate = labour + material + plant + subcontract + overheads + profit, expressed per unit of measurement (m³, m², m, nr).

Labour output is expressed as hours per unit; cost = hours × hourly rate including social insurance and allowances.

Quantity take-off follows the measurement rules of the chosen standard method; items are grouped by work section and measured net unless rules state otherwise.

Preliminaries (site establishment, supervision, temporary works, insurance) are priced separately and are not distributed into unit rates.

Cash flow and cost control use earned value: CPI = EV/AC and SPI = EV/PV; a CPI below 1.0 indicates cost overrun.

Contingency is an allowance for identified but unquantified risk; it is held in the estimate and released as risk is retired.

Quality control of concrete: slump test for workability, cube tests at 7 and 28 days for strength, and cover meter checks for reinforcement position.

Inspection and test plans (ITPs) define hold points where work cannot proceed without documented verification and sign-off.

Equilibrium of a planar rigid body requires ΣFx = 0, ΣFy = 0, ΣM = 0 about any point; three independent equations solve three unknowns.

Moment of a force about a point: M = F·d, where d is the perpendicular distance from the point to the line of action; sign convention must be fixed before summing.

Resultant of a concurrent force system: Rx = ΣFx, Ry = ΣFy, R = √(Rx² + Ry²), direction θ = arctan(Ry/Rx) measured from the x-axis.

Centroid of a composite area: x̄ = Σ(Ai·x̄i)/ΣAi, ȳ = Σ(Ai·ȳi)/ΣAi; for a triangle the centroid lies at one-third of the height from the base.

Friction limit: impending sliding occurs when F = μs·N; kinetic friction F = μk·N applies once motion starts, with μk < μs.

Equations of motion for constant acceleration: v = u + at, s = ut + ½at², v² = u² + 2as; these apply only when a is constant.

Newton's second law for a particle: ΣF = m·a; for a rigid body in plane motion the couple equation ΣM_G = I_G·α is added.

Work-energy principle: U₁₋₂ = ΔT, where work by a constant force is F·s·cosθ and kinetic energy T = ½mv²; power P = F·v.

Axial stress σ = N/A; axial strain ε = ΔL/L; Hooke's law σ = E·ε applies within the elastic limit, with E in GPa for steel (about 200 GPa).

Elongation of an axially loaded bar: ΔL = N·L/(A·E); for stepped or varying loads sum the contributions of each segment.

Bending stress: σ = M·y/I, maximum at the extreme fibre with y = c; section modulus W = I/c gives σmax = M/W.

Second moment of area for a rectangle about its centroidal axis: I = b·h³/12; parallel axis theorem I = I_c + A·d².

Shear stress in bending: τ = V·Q/(I·b); τ is zero at the extreme fibres and maximum at the neutral axis for a rectangular section.

Deflection of a simply supported beam under central point load P: δmax = P·L³/(48·E·I) at midspan.

Euler buckling load for a pin-ended column: Pcr = π²·E·I/L²; effective length factors reduce capacity for other end conditions.

Determinacy of a plane truss: m + r = 2j for statically determinate; m + r > 2j indicates redundancy, m + r < 2j indicates instability.

Concrete characteristic strength fck is the 28-day cube strength below which no more than 5% of test results should fall; cylinder strength ≈ 0.8 × cube strength.

Concrete mix design targets water/cement ratio and exposure class; lower w/c increases strength and durability but reduces workability.

Cement types: CEM I (Portland), CEM II (Portland-composite), CEM III (blastfurnace), CEM IV (pozzolanic), CEM V (composite); sulfate-resistant and low-heat grades are selected for aggressive ground or mass pours.

Reinforcement: B500 deformed bars have characteristic yield strength 500 MPa; nominal cover is set by exposure class and fire resistance, not by bar diameter alone.

Concrete curing must retain moisture; stripping times depend on member type and achieved strength, typically verified by cube tests or maturity methods.

Masonry: mortar designation (M2.5 to M12) is chosen with unit strength; movement joints are required at intervals to accommodate thermal and moisture expansion.

Structural steel grade S275 or S355 denotes minimum yield strength in MPa; bolted connections use preloaded or bearing-type bolts per design category.

Bituminous mixtures are specified by aggregate gradation, binder grade and air voids; compaction temperature window is set by binder viscosity.

First-angle projection places the view from above below the front view; third-angle projection places it above; the projection symbol on the drawing identifies which system applies.

Scale notation 1:100 means 1 unit on the drawing equals 100 units on site; a 25 mm dimension on a 1:100 drawing represents 2.5 m.

Line hierarchy: continuous thick for visible outlines, continuous thin for dimension and projection lines, dashed for hidden edges, chain lines for centre lines and section planes.

A section drawing is identified by cutting-plane line with arrows showing viewing direction and by a section label (e.g. A-A).

Levels are annotated with a datum symbol and value in metres to three decimals, e.g. +3.450; the project datum is stated on the drawing title block.

Reinforcement drawings use bar marks with diameter, spacing and shape code; the bending schedule lists total lengths and weights per bar mark.

Drawing register and revision control: superseded drawings must be marked, and only the latest revision is valid for construction.

Levelling: height difference between two points = backsight reading − foresight reading; reduced level = known RL + backsight − foresight (height of collimation method).

Rise and fall method checks that Σbacksight − Σforesight = Σrise − Σfall = last RL − first RL.

Closed traverse angular check: sum of measured interior angles should equal (n−2)·180°; misclosure is distributed equally among the angles.

Coordinate computation from bearing and distance: ΔE = d·sinθ, ΔN = d·cosθ, with bearings measured clockwise from north.

Total station measures slope distance, then horizontal distance = slope distance × cos(vertical angle); EDM accuracy is quoted as ±(a + b ppm).

Volume by end areas: V = L·(A₁ + A₂)/2 for a prismoid segment; prismoidal formula V = L·(A₁ + 4Am + A₂)/6 is more accurate.

Setting out: right angles by 3-4-5 triangle or by theodolite; a baseline is established first and offsets are measured perpendicular to it.

Tolerance for setting out is project-specific; structural grid lines are typically checked against the design coordinates before any concrete is placed.

Electrical supply in Cyprus is 230 V single-phase, 50 Hz; three-phase distribution is 400 V between phases.

Protection: an RCD rated 30 mA is required for socket circuits and wet areas; MCBs protect against overload and short circuit and are selected to the cable current-carrying capacity.

Earthing system types (TN-S, TN-C-S, TT) determine the protective measures and the need for an earth electrode at the installation.

Plumbing: hot water distribution uses a secondary return or is kept short to limit dead legs; pressure-reducing valves are fitted where mains pressure exceeds fixture rating.

Drainage: soil and waste stacks require ventilation to prevent trap seal loss; trap seals are nominally 50 mm minimum.

HVAC sizing: heating load by fabric transmission plus ventilation; cooling load includes solar gains, internal gains and latent load, not just temperature difference.

Ventilation rates are set per occupancy and use; mechanical extract is required in kitchens and sanitary spaces without openable windows.

Fire detection and alarm systems are zoned to limit the search area; sounders must achieve the specified sound pressure level at the bedhead or in occupied rooms.

Hierarchy of control: eliminate, substitute, engineering controls, administrative controls, then personal protective equipment as the last line of defence.

Working at height is the leading cause of fatal construction accidents; collective protection (guardrails, nets) takes priority over personal fall arrest.

Excavations: support or batter sides, keep spoil back from the edge, provide ladders within 25 m of travel, and inspect after rain or any ground movement.

Scaffolding must be erected, altered and dismantled by competent persons; it is inspected before first use and at intervals not exceeding 7 days.

Site induction and task-specific briefing are required before any worker starts; visitors must be escorted and issued PPE.

Site layout: separate pedestrian and vehicle routes, locate storage and plant away from excavations, and position welfare facilities within reasonable distance of the works.

Emergency arrangements: fire points, escape routes, assembly point, first-aid provision and emergency contact numbers are displayed on site.

Lifting operations require a plan by a competent person; exclusion zones are maintained beneath suspended loads and no person may ride on a load.

Building permits: construction may not start before the planning and building permit is issued by the competent authority; deviations require a revised permit.

Cyprus building regulation references include the national seismic design provisions aligned with Eurocode 8 and the Eurocodes adopted as national standards.

Contract forms allocate risk: lump-sum contracts place quantity risk on the contractor; measurement (re-measurement) contracts pay for actual quantities executed.

Variations must be instructed in writing by the contract administrator; without a written instruction, the contractor's entitlement to payment is weak.

Time provisions: extension of time is granted for employer-risk events; liquidated damages apply for culpable delay at a stated rate per day.

Retention is typically deducted from interim payments and released in two parts - on practical completion and after the defects liability period.

Interim payment certificates are issued at stated intervals; the contractor submits an application and the certifier assesses the value of work executed.

Health and safety duties are imposed on the client, designer and contractor, who must cooperate and coordinate; the client must appoint competent persons.

Unit-rate estimating: rate = labour + material + plant + subcontract + overheads + profit, expressed per unit of measurement (m³, m², m, nr).

Labour output is expressed as hours per unit; cost = hours × hourly rate including social insurance and allowances.

Quantity take-off follows the measurement rules of the chosen standard method; items are grouped by work section and measured net unless rules state otherwise.

Preliminaries (site establishment, supervision, temporary works, insurance) are priced separately and are not distributed into unit rates.

Cash flow and cost control use earned value: CPI = EV/AC and SPI = EV/PV; a CPI below 1.0 indicates cost overrun.

Contingency is an allowance for identified but unquantified risk; it is held in the estimate and released as risk is retired.

Quality control of concrete: slump test for workability, cube tests at 7 and 28 days for strength, and cover meter checks for reinforcement position.

Inspection and test plans (ITPs) define hold points where work cannot proceed without documented verification and sign-off.

Equilibrium of a planar rigid body requires ΣFx = 0, ΣFy = 0, ΣM = 0 about any point; three independent equations solve three unknowns.

Moment of a force about a point: M = F·d, where d is the perpendicular distance from the point to the line of action; sign convention must be fixed before summing.

Resultant of a concurrent force system: Rx = ΣFx, Ry = ΣFy, R = √(Rx² + Ry²), direction θ = arctan(Ry/Rx) measured from the x-axis.

Centroid of a composite area: x̄ = Σ(Ai·x̄i)/ΣAi, ȳ = Σ(Ai·ȳi)/ΣAi; for a triangle the centroid lies at one-third of the height from the base.

Friction limit: impending sliding occurs when F = μs·N; kinetic friction F = μk·N applies once motion starts, with μk < μs.

Equations of motion for constant acceleration: v = u + at, s = ut + ½at², v² = u² + 2as; these apply only when a is constant.

Newton's second law for a particle: ΣF = m·a; for a rigid body in plane motion the couple equation ΣM_G = I_G·α is added.

Work-energy principle: U₁₋₂ = ΔT, where work by a constant force is F·s·cosθ and kinetic energy T = ½mv²; power P = F·v.

Axial stress σ = N/A; axial strain ε = ΔL/L; Hooke's law σ = E·ε applies within the elastic limit, with E in GPa for steel (about 200 GPa).

Elongation of an axially loaded bar: ΔL = N·L/(A·E); for stepped or varying loads sum the contributions of each segment.

Bending stress: σ = M·y/I, maximum at the extreme fibre with y = c; section modulus W = I/c gives σmax = M/W.

Second moment of area for a rectangle about its centroidal axis: I = b·h³/12; parallel axis theorem I = I_c + A·d².

Shear stress in bending: τ = V·Q/(I·b); τ is zero at the extreme fibres and maximum at the neutral axis for a rectangular section.

Deflection of a simply supported beam under central point load P: δmax = P·L³/(48·E·I) at midspan.

Euler buckling load for a pin-ended column: Pcr = π²·E·I/L²; effective length factors reduce capacity for other end conditions.

Determinacy of a plane truss: m + r = 2j for statically determinate; m + r > 2j indicates redundancy, m + r < 2j indicates instability.

Concrete characteristic strength fck is the 28-day cube strength below which no more than 5% of test results should fall; cylinder strength ≈ 0.8 × cube strength.

Concrete mix design targets water/cement ratio and exposure class; lower w/c increases strength and durability but reduces workability.

Cement types: CEM I (Portland), CEM II (Portland-composite), CEM III (blastfurnace), CEM IV (pozzolanic), CEM V (composite); sulfate-resistant and low-heat grades are selected for aggressive ground or mass pours.

Reinforcement: B500 deformed bars have characteristic yield strength 500 MPa; nominal cover is set by exposure class and fire resistance, not by bar diameter alone.

Concrete curing must retain moisture; stripping times depend on member type and achieved strength, typically verified by cube tests or maturity methods.

Masonry: mortar designation (M2.5 to M12) is chosen with unit strength; movement joints are required at intervals to accommodate thermal and moisture expansion.

Structural steel grade S275 or S355 denotes minimum yield strength in MPa; bolted connections use preloaded or bearing-type bolts per design category.

Bituminous mixtures are specified by aggregate gradation, binder grade and air voids; compaction temperature window is set by binder viscosity.

First-angle projection places the view from above below the front view; third-angle projection places it above; the projection symbol on the drawing identifies which system applies.

Scale notation 1:100 means 1 unit on the drawing equals 100 units on site; a 25 mm dimension on a 1:100 drawing represents 2.5 m.

Line hierarchy: continuous thick for visible outlines, continuous thin for dimension and projection lines, dashed for hidden edges, chain lines for centre lines and section planes.

A section drawing is identified by cutting-plane line with arrows showing viewing direction and by a section label (e.g. A-A).

Levels are annotated with a datum symbol and value in metres to three decimals, e.g. +3.450; the project datum is stated on the drawing title block.

Reinforcement drawings use bar marks with diameter, spacing and shape code; the bending schedule lists total lengths and weights per bar mark.

Drawing register and revision control: superseded drawings must be marked, and only the latest revision is valid for construction.

Levelling: height difference between two points = backsight reading − foresight reading; reduced level = known RL + backsight − foresight (height of collimation method).

Rise and fall method checks that Σbacksight − Σforesight = Σrise − Σfall = last RL − first RL.

Closed traverse angular check: sum of measured interior angles should equal (n−2)·180°; misclosure is distributed equally among the angles.

Coordinate computation from bearing and distance: ΔE = d·sinθ, ΔN = d·cosθ, with bearings measured clockwise from north.

Total station measures slope distance, then horizontal distance = slope distance × cos(vertical angle); EDM accuracy is quoted as ±(a + b ppm).

Volume by end areas: V = L·(A₁ + A₂)/2 for a prismoid segment; prismoidal formula V = L·(A₁ + 4Am + A₂)/6 is more accurate.

Setting out: right angles by 3-4-5 triangle or by theodolite; a baseline is established first and offsets are measured perpendicular to it.

Tolerance for setting out is project-specific; structural grid lines are typically checked against the design coordinates before any concrete is placed.

Electrical supply in Cyprus is 230 V single-phase, 50 Hz; three-phase distribution is 400 V between phases.

Protection: an RCD rated 30 mA is required for socket circuits and wet areas; MCBs protect against overload and short circuit and are selected to the cable current-carrying capacity.

Earthing system types (TN-S, TN-C-S, TT) determine the protective measures and the need for an earth electrode at the installation.

Plumbing: hot water distribution uses a secondary return or is kept short to limit dead legs; pressure-reducing valves are fitted where mains pressure exceeds fixture rating.

Drainage: soil and waste stacks require ventilation to prevent trap seal loss; trap seals are nominally 50 mm minimum.

HVAC sizing: heating load by fabric transmission plus ventilation; cooling load includes solar gains, internal gains and latent load, not just temperature difference.

Ventilation rates are set per occupancy and use; mechanical extract is required in kitchens and sanitary spaces without openable windows.

Fire detection and alarm systems are zoned to limit the search area; sounders must achieve the specified sound pressure level at the bedhead or in occupied rooms.

Hierarchy of control: eliminate, substitute, engineering controls, administrative controls, then personal protective equipment as the last line of defence.

Working at height is the leading cause of fatal construction accidents; collective protection (guardrails, nets) takes priority over personal fall arrest.

Excavations: support or batter sides, keep spoil back from the edge, provide ladders within 25 m of travel, and inspect after rain or any ground movement.

Scaffolding must be erected, altered and dismantled by competent persons; it is inspected before first use and at intervals not exceeding 7 days.

Site induction and task-specific briefing are required before any worker starts; visitors must be escorted and issued PPE.

Site layout: separate pedestrian and vehicle routes, locate storage and plant away from excavations, and position welfare facilities within reasonable distance of the works.

Emergency arrangements: fire points, escape routes, assembly point, first-aid provision and emergency contact numbers are displayed on site.

Lifting operations require a plan by a competent person; exclusion zones are maintained beneath suspended loads and no person may ride on a load.

Building permits: construction may not start before the planning and building permit is issued by the competent authority; deviations require a revised permit.

Cyprus building regulation references include the national seismic design provisions aligned with Eurocode 8 and the Eurocodes adopted as national standards.

Contract forms allocate risk: lump-sum contracts place quantity risk on the contractor; measurement (re-measurement) contracts pay for actual quantities executed.

Variations must be instructed in writing by the contract administrator; without a written instruction, the contractor's entitlement to payment is weak.

Time provisions: extension of time is granted for employer-risk events; liquidated damages apply for culpable delay at a stated rate per day.

Retention is typically deducted from interim payments and released in two parts - on practical completion and after the defects liability period.

Interim payment certificates are issued at stated intervals; the contractor submits an application and the certifier assesses the value of work executed.

Health and safety duties are imposed on the client, designer and contractor, who must cooperate and coordinate; the client must appoint competent persons.

Unit-rate estimating: rate = labour + material + plant + subcontract + overheads + profit, expressed per unit of measurement (m³, m², m, nr).

Labour output is expressed as hours per unit; cost = hours × hourly rate including social insurance and allowances.

Quantity take-off follows the measurement rules of the chosen standard method; items are grouped by work section and measured net unless rules state otherwise.

Preliminaries (site establishment, supervision, temporary works, insurance) are priced separately and are not distributed into unit rates.

Cash flow and cost control use earned value: CPI = EV/AC and SPI = EV/PV; a CPI below 1.0 indicates cost overrun.

Contingency is an allowance for identified but unquantified risk; it is held in the estimate and released as risk is retired.

Quality control of concrete: slump test for workability, cube tests at 7 and 28 days for strength, and cover meter checks for reinforcement position.

Inspection and test plans (ITPs) define hold points where work cannot proceed without documented verification and sign-off.