PE Construction cheat sheet

WBS decomposes scope into deliverable-oriented levels; the lowest level, the work package, is the unit for estimating, scheduling, and responsibility assignment.

PERT expected duration te = (a + 4m + b) / 6; standard deviation = (b - a) / 6.

Total float = LS - ES = LF - EF; free float = ES(successor) - EF(activity).

The critical path is the longest continuous path through the network; it has zero total float and sets project duration.

Gantt bar charts show timing but not logic ties; CPM and PERT networks show dependencies and float.

Constructability review applies construction knowledge during design to reduce cost, schedule, and safety risk.

Life-cycle cost = initial capital cost + present value of operations, maintenance, and replacement over the service life.

Regulatory approvals (NPDES stormwater permit, environmental permits, building permits) should be identified during preconstruction planning.

Earth retention selection: sheet piles for high groundwater and tight sites; soldier piles with lagging for stiff soils; slurry walls for deep cuts; secant piles where groundwater cutoff is needed.

Dewatering selection: sumps for shallow seepage; wellpoints for drawdown to about 4-6 m; deep wells for greater depths; ejectors for low-permeability fine soils.

Crane load charts give capacity as a function of radius and boom length; required capacity includes the load, rigging, and block weight.

Underwater concrete is placed by tremie with the pipe discharge kept submerged; free fall in air is limited to about 1.5 m to prevent segregation.

Compaction equipment: smooth-drum rollers for granular base; sheepsfoot for cohesive soils; vibratory rollers for granular soils; pneumatic-tired rollers for both.

OSHA 1926 Subpart P: trenches 5 ft or deeper need a protective system; spoil and equipment are kept at least 2 ft from the edge.

Asphalt compaction follows breakdown, intermediate, and finish rolling within a specified temperature window; rolling too cold yields inadequate density.

Formwork design pressure depends on concrete placement rate, concrete temperature, slump, and the consolidation method.

Effective stress sigma' = sigma - u; Mohr-Coulomb shear strength tau = c' + sigma' tan(phi').

Atterberg limits: PI = LL - PL; high-plasticity clays are expansive and prone to shrink-swell.

Modified Proctor (ASTM D1557) uses more compaction energy than Standard Proctor (ASTM D698), giving higher maximum dry unit weight at lower optimum moisture content.

Consolidation settlement Sc = [Cc H / (1 + e0)] log10[(sigma'0 + delta sigma) / sigma'0].

Darcy's law: q = k i A, where i is the hydraulic gradient equal to head loss divided by flow length.

Relative density Dr = [(emax - e) / (emax - emin)] x 100%; granular soils above about 70% relative density are considered dense.

Liquefaction risk is highest in loose, saturated, uniformly graded sands with shallow groundwater under seismic loading.

Bearing capacity failure modes: general shear in dense soils, local and punching shear in loose soils; a factor of safety of 3 is typical for shallow foundations.

Static equilibrium requires sum of forces in x and y equal zero and sum of moments about any point equal zero.

Simple beam with uniform load w: maximum moment wL^2/8 at midspan; maximum shear wL/2 at the supports.

Cantilever with uniform load w: maximum moment wL^2/2 at the fixed support.

Simple beam with a point load P at midspan: maximum moment PL/4.

Bending stress sigma = M/S with section modulus S = I/c; horizontal shear stress tau = VQ/(It).

Euler buckling: Pcr = pi^2 EI / (KL)^2; K = 1.0 pinned-pinned, 0.5 fixed-fixed, 0.7 fixed-pinned, 2.0 fixed-free.

Shear diagram slope equals the distributed load; moment diagram slope equals shear; maximum moment occurs where shear crosses zero.

Truss analysis assumes pinned joints and loads applied only at joints; member forces are found by method of joints or method of sections.

Rational method: Q = CiA; rainfall intensity is selected for a duration equal to the time of concentration.

Manning equation in US customary units: V = (1.486/n) R^(2/3) S^(1/2), and Q = VA.

NRCS curve number: S = 1000/CN - 10; Q = (P - 0.2S)^2 / (P + 0.8S) when P exceeds 0.2S.

Orifice flow Q = C A sqrt(2gH); weir flow Q = C L H^(3/2).

Darcy-Weisbach head loss hf = f (L/D) (V^2/2g); Hazen-Williams is commonly used for water distribution piping.

Detention storage volume equals the area between the inflow and outflow hydrographs.

Stormwater pollution prevention plans typically require silt fence, check dams, inlet protection, and sediment basins.

Concrete strength and durability are governed mainly by water-cement ratio; typical structural ratios are 0.40 to 0.50.

Design compressive strength is based on 28-day cylinder tests (6x12 in or 4x8 in specimens tested per ASTM C39).

Air entrainment of 4-8% improves freeze-thaw resistance; each percent of entrained air reduces compressive strength by roughly 3-5%.

Slump (ASTM C143) measures consistency and workability, not strength; water should be adjusted at the batch plant, not added at the site.

ASTM A615 Grade 60 reinforcement has a specified yield strength of 60 ksi.

Mortar types in descending compressive strength order: M, S, N, O, K.

Asphalt PG binder grades such as PG 64-22 denote high and low pavement service temperatures in degrees Celsius.

Curing maintains moisture and temperature above 50 F for about 7 days, or 14 days for high-early-strength or severe exposure conditions.

Bank, loose, and compacted volumes relate through swell and shrinkage; compacted volume = bank volume x (1 - shrinkage).

Load factor = loose volume / bank volume; shrinkage = 1 - (compacted volume / bank volume).

Crane required capacity = load + rigging + block weight; verify the pick against the load chart at the maximum working radius.

Concrete pumping requires adequate slump and a pump line diameter compatible with maximum aggregate size; prime with grout and control vertical free fall.

Trenchless methods include horizontal directional drilling, microtunneling, pipe bursting, and auger boring.

Deep excavation monitoring uses settlement points, inclinometers, and piezometers to detect wall movement and groundwater change.

Steel erection fall protection is required at 15 ft; controlled decking zones are limited to specific leading-edge work with written procedures.

Hot-weather concreting: cool aggregates and mixing water, use retarders, place at lower slump, and cure immediately; avoid placement above about 90 F ambient.

Forward pass: ES = maximum EF of predecessors; EF = ES + duration.

Backward pass: LF = minimum LS of successors; LS = LF - duration.

Total float = LS - ES = LF - EF; critical path activities have zero total float.

Free float = ES(successor) - EF(activity); it is the delay possible without affecting any successor's early start.

Lag adds required waiting time between activities; lead allows overlap and is modeled as negative lag.

Resource leveling shifts activities within float to smooth resource peaks and may extend project duration.

Crashing adds resources to critical-path activities, prioritizing the lowest cost-per-day slope first.

Fast-tracking overlaps sequential activities and increases coordination and rework risk.

AACE estimate classes range from Class 5 conceptual at -30%/+50% accuracy to Class 1 definitive at -5%/+10% accuracy.

Unit cost buildup: material + labor + equipment + subcontract + indirect costs + overhead + profit.

Contingency covers identified and unidentified risk; the allowance decreases as design and estimate maturity increase.

Earned value: EV = percent complete x BAC; CV = EV - AC; SV = EV - PV.

CPI = EV/AC and SPI = EV/PV; values below 1.0 indicate over budget or behind schedule.

EAC = BAC/CPI when the current cost trend continues; EAC = AC + (BAC - EV) when remaining work proceeds at the budget rate.

Labor productivity must be adjusted for weather, site access, and crew skill; crew-day output is the usual estimating unit.

Change order pricing order: contract unit rates first, then negotiated lump sum, then time and materials with documented costs.

Contract types include lump sum, unit price, cost-plus-fixed-fee, guaranteed maximum price, and design-build; each shifts cost risk differently between owner and contractor.

AIA A201 General Conditions defines owner, contractor, and architect roles; AIA A101 is the owner-contractor agreement form.

Submittals, RFIs, and change orders must follow contractual time limits; failure to respond within the stated period can be deemed approval.

Type I differing site condition: a latent subsurface or hidden physical condition differing materially from the contract documents.

Type II differing site condition: an unknown physical condition of an unusual nature differing from conditions ordinarily encountered.

Concurrent owner and contractor delay generally bars compensable delay damages for either party.

Performance bonds guarantee completion; payment bonds guarantee payment to subcontractors and suppliers; the Miller Act covers federal work.

Substantial completion allows owner occupancy and starts warranty periods; final completion follows punch list closeout.

OSHA 29 CFR 1926 governs construction; Subpart M requires conventional fall protection at 6 ft for general construction work.

Scaffold fall protection is required at 10 ft; steel erection fall protection is required at 15 ft.

Excavations 5 ft or deeper require a protective system unless a competent person determines there is no hazard.

Spoil, materials, and equipment are kept at least 2 ft from excavation edges; ladders are required within 25 ft of lateral travel in trenches 4 ft deep or more.

Crane clearance from power lines: 10 ft for lines up to 50 kV, with greater distances at higher voltages per the OSHA table.

A competent person identifies existing and predictable hazards and has authority to take prompt corrective action; required for excavations, scaffolds, and fall protection.

Permit-required confined spaces require atmospheric testing, an attendant stationed outside, and a rescue plan before entry.

OSHA 1926.1153 silica exposure controls include engineering controls such as wet cutting, respiratory protection, and medical surveillance above the action level.