Civil Engineering 2810
Site preparation
Things to consider on the ground, above the ground, underground
Marine Construction
Oil platforms, harbors, artificial islands
Multiple Prime Contracting
Owner directly retains subs or trade contractors to perform a major portion of the work Advantages: Avoidance of fee to GC (cost benefit), owner can fast-tract project (time benefit) Disadvantages: Owner is responsible for planning and coordinating the project
Construction Management (At-Risk)
Owner retains a CM to be more accountable in coordinating A/E and GC Advantages: Involved in project development process from the incipient, assist owner and A/E to follow fast-tract Disadvantages: Does not take on the risk of design problems
Construction Management (Consulting)
Owner retains a CM to coordinate and assist A/E and GC from predesign to construction phases. Advantages: CM's expertise in project management (scheduling and coordinating A/E and GC) Disadvantages: Additional cost and layer of consulting service (VE can offset this disadvantage), overlapping duty with A/E (ex: scheduling, quality control), unaccountability for quality, cost and time overruns
Owner
Private and public firms, government (public) organizations.
Leads
Purpose: to align pile and hammer while driving - Swinging leads - Semi-fixed - Fixed
Dewatering with Wellpoints
- 2ft to 10ft interval - Capacity: 3 to 30 gal/min/point - Effective depth 20ft - Single stage - Multiple stages - Deep wells
Mass Diagram
- A curve that represents accumulated volume of cut and fill between two or more stations - A peak of the curve represents the station where the earthwork changes from cut to fill - A valley of the curve represents the station where the earthwork changes from fill to cut - A balance line is a horizontal line that intersects the mass curve at stations in which the accumulated volumes at these stations are equal
Transporting Concrete
- Avoid over- or under-agitate - Over-agitate will cause bleeding - Under-agitate will cause segregation - Watch for traffic which may cause delay - Take set retarding agent into account when transporting concrete
Vibratory Hammer
- Best used for steel sheet piles - When used for steel bearing piles, the last 15ft will need impact hammer - Drives fast
Pile Cushions
- Between the pile top and the pile cap on concrete piles - Not for steel or timber piles - From plywood, replaced after each pile
Air Compressor Types
- Centrifugal (dynamic) - Reciprocating (positive displacement) - Rotary (positive displacement)
Water Pump Types
- Centrifugal pumps - Reciprocating pumps - Diaphragm pumps - Submersible pumps
Air/Steam Hammer
- Cleaner than diesel - More efficient than diesel - Consistent operating rate - Low impact velocity - Need support equipment
Placing Concrete
- Concrete Pump (Trailer pump & Boom pump) - Crane and Bucket/Chute - Conveyor belt
Purpose of Curing Concrete
- Control humidity and temperature of fresh concrete - Prolong hydration of cement - Reduce concrete internal void - Protect concrete from extreme weather condition - Protect concrete from vibration, impact and other disturbances during curing
Hydraulic Hammer
- Controllable stroke with precise pressure setting - Low impact velocity - High efficiency blow - Clean and quiet operation - Need support equipment (hydraulic power unit) - Need hydraulic operator
Dewatering
- Ditches and submersible pumps (soil grain size > 0.1 mm) - Regular wellpoints (alternative to ditches) (soil grain size > 0.1 mm) - Gravity deep well system (for large volume of water; soil grain size > 0.1 mm) - Vacuum wellpoints (0.1 mm > soil grain size > 0.004 mm) - Electro-osmosis (0.004 mm > soil grain size > 0.0017 mm)
Closed-end Hammer
- Enclosed top - Pressure build up in the bounce pressure chamber - Drivers piles faster - Ram (hammer) not visible
Template
- For swinging leads or semi-fixed leads - Must be rigid to support the pile
Pile Driving Crane Parts
- Hammer - Cushion - Leads - Template
Selection of A/E
Advertisement by owner in Commerce Business Daily (CBD), advertisement in appropriate professional journals and periodicals, interview process, selection decision
Franki pile (bulb pile)
- Install steel case and plug with gravels - Perform bottom driving with hammer. Gravels displace soil laterally. - Continue driving to form Franki base. - Install Reinforcement - Complete driving to form Franki bulb - Pour SCC (self consolidating concrete) zero slump superplasticizer, hammer concrete and successively withdraw steel case - Complete pouring, driving and withdrawing steel case to form the Franki pile
Concrete Operation
- Make sure you have the right mix constituents - Take weather into account (e.g., in cold weather include heating aggregate, etc.) - Add admixture if needed (e.g., accelerator in cold weather and retarder in hot weather) - Clean areas before concreting; do not place concrete on frozen - Pour concrete between 50 to 90 degrees F - Always cure concrete after finishing - Use in place maturity meter if needed - During extreme weather condition, place concrete on the right time of day
Dewatering with Ditches
- Slope 50:1 - Dewatering pit/well - Discharge tank/sewer - Temporary and permanent pits
Pile Types
- Steel sheet piles - Steel H piles - Steel pipe piles - Cast-in-place concrete (bored) piles - P/S Concrete piles
Hammer Cushions (Capblocks)
- To protect hammer and pile - Located between anvil and pile cap - Materials include aluminum (0.5 inch), micarta (1inch) and polymer
Tools used for Finishing Concrete
- Trowels - Darby - Groovers - Screeders - Bull floats
Unacceptable Templates
- Unfixed template from timber - Template attached to floating barge
Curing Concrete
- Water ponding/spraying/sprinkling - Keep moisture in place - Jet air - Ice - Vapor Curing - Leave formwork in place
Mixing Concrete
- Water/Concrete ratio 1% by weight is equivalent to 100 psi difference - Improper use of Air Entraining Agents (AEA) for durability due to freeze-thaw condition may result in porous concrete - Improper use of Water Reducing Agents (WRA) may result in segregation and reduced strength of concrete - Improper use of set accelerating agents may reduce concrete durability and rebar corrosion - Improper use of set retarding agents to delay setting of concrete during transport may result in bleeding, cold joints and finishing difficulties - Remixing may result in cold joints
Dewatering with Vacuum Wellpoints
- Wellpoints are sealed at the surface with a ring of bentonite or clay - Vacuum pump is connected to header pipe - Differential pressure between the well and surrounding ground water accelerates water flow
Open-end Hammer
- Widely used - Simple and dependable - Open on top - Visible ram going up and down
Types of Construction Projects
1) Horizontal 2) Vertical 3) Plants/Industrial 4) Marine 5) Underground 6) Space
Characteristics of Construction Industry
1) Service oriented 2) Does not accumulate a large amount of capital 3) Very fragmented and characterized by participation of numerous parties 4) Often includes unprecedented type of construction 5) Broad range of facilities
Fine-Grained Soils
50% or more passes the #200 sieve
Trench Width
< 15 ft (less than)
% Shrinkage
= (1 - Shrinkage factor) * 100
Shrinkage Factor
= (Bank weight/cy) / (Compacted weight/cy)
Swell Factor
= (Loose weight/cy) / (Bank weight/cy)
Moisture/Water Content
= (Moist weight - Dry weight)/Dry weight * 100 (%)
% Swell
= [(Bank weight/cy) / (Loose weight/cy) - 1] * 100
Excavation Width
> 15 ft (greater than)
Partnering
A process to avoid dispute in a project specifically involving inter-organizational parties Advantages: reduce residual litigation claims after completion, reduce cost/time overruns, solve problems quickly Disadvantages: Does not have legal bind (hand shake approach), generally not repeatable with same partners, only for project specifics
Design-Bid-Build
A three party approach: owner, A/E, and GC Advantages: Price competition on design the owner has commissioned, no potential conflict of interest between design and construction Disadvantages: Lack of contractors influence in the design, lack of trust between designers and contractors, place the owner in the middle of conflict between designer and contractor, inefficient scheduling, increase claims and dispute
Intermediate Design
A/E will develop and obtain owner's approval for architectural drawings, structural drawings, mechanical drawings, electrical drawings, refined cost estimate, and refined specifications
Construction Phase
A/E will function as the owner's rep, monitor project for its compliance with drawings and specs, approve and review shop drawing performed by GC or sub, issue changes, evaluate progress and approve payment to GC, conduct final inspection and approval of the entire project
Final Design
A/E will obtain building permit from the authority, A/E will furnish and obtain owner's approval for final bid drawings, final specifications, final cost estimate, final project timeline
Bidding phase
A/E will pre-qualify GCs, issue bid document, conduct a preconstruction meeting, award contract to the lowest bidder
Quantity Surveyor
An organization or a person performing cost analysis, feasibility study, value engineering, risk analysis, and resource allocations in a construction project
Average End Area Method
Assumes volume between two consecutive cross sections is the average of their areas multiplied by the distance between them V = L (A1 + A2) / (2 * 27)
Silt
Between 0.005mm and 0.074mm (#200 sieve)
Sand
Between 0.074mm (#200 sieve) and 6mm (#4 sieve)
Gravel
Between 6mm (#4 sieve) and 3 inches
Fixed Leads
Both top and bottom of leads are fixed
Fixed Time
Consists of: - Loading time - Turning, acceleration, deceleration time - Placing time
Construction Manager
Consultant, At-risk
Travel Time
Depends on: - Rolling Resistance - Grade Resistance - Rimpull Required - Available and usable Rimpull - Travel Speed
Productivity of a Dozer
Depends on: - Type of blade - Type of Material - Cycle Time
Project Delivery (Contractual Approaches)
Design-Bid-Build, Multiple prime contracting (MPC), construction management (consulting), construction management (at-risk), Design-Build
Fast-tract
Doing the design and construction of a project at the same time to speed up the process. Is best with repetitive projects. Not good with unprecedented projects.
Air Compressors
Needed for machineries, pneumatic tools, and pumps
Semi-fixed Leads
Either top or bottom of leads is fixed
Horizontal Construction
Ex. Bridges, highways, canals, pipelines, tunnels, railroads, dams
Vertical Construction
Ex. Hi-rise buildings, arenas/stadia, domes, hangars, monuments, towers
Plants/Industrial Construction
Ex. Oil refineries, Nuclear power plants, Cooling towers, silos, transmission towers
Dual Coarse-Grained
From 5% to 12% (inclusive) finer than #200 sieve
Vendors
Heavy equipment, RMC, prefab P/S concrete, steel piles, steel girders
Hammer
Impact Hammers - Open-end diesel - Closed-end diesel - Air/Steam hammer - Hydraulic hammer Vibratory Hammers
Architect/Engineer (A/E)
In house, independent
QA/QC
Independent organization retained by the owner to maintain the quality of construction operations and results, mandatory for several European countries especially those involving high-risk structures.
Clay
Less than 0.005mm
Clean Coarse-Grained
Less than 5% finer than #200 sieve
Coarse-Grained Soils
Less than 50% is finer than the #200 sieve
Dirty Coarse-Grained
More than 12% finer than #200 sieve
Water Pumps
Needed for dewatering ponds, dewatering excavation and dewatering basement
Value Engineering
Owner retains a VE to reevaluate the design and construction operations Advantages: Analysis of function and quality of construction operations, methods, alternatives that may result in cost savings Disadvantages: VE takes time to perform, if it ay result in cost saving then why not perform from start? If so it could save additional VE fee, various starting points (ex: 18% of work progress)
Design-Build
Owner retains a single party for design and construction Advantages: Single point of responsibility, reduced owner's uninsurable risk (project delay), facilitated and efficient scheduling, streamlined coordination of design and construction, effective fast-tracking, ability to respond quickly to changing owner's needs Disadvantages: Not suitable for every project due to legal constraint, not often used (not an option) by public owner or government, limit ingenuity and creativity of the design-builder's team, can place the owner right back in the position of warranting adequacy of design
Players in a Construction Project
Owner, Architect/Engineer (A/E), Construction manager, General contractor, sub/specialty contractors, vendors, QA/QC, Value engineers, quantity surveyors
Preliminary Design
Owners design criteria for a building (location, space number of stories), design criteria for a bridge (location and length, number of lanes, type of bridge), sometimes the community needs to be consulted for these criteria, environmental issues (EPA approval), A/E will provide the owner with: various design alternatives, outline specification, brief project estimate and timeline, potential consulting engineers, A/E will obtain owners approval for all of the above
Plasticity Index (PI)
PI = LL - PL The range of water content in which soil remains plastic
Above ground
Power lines, trees, neighboring structures, lamp posts, traffic signs, fire hydrants
Grade Resistance (GR)
Resistance due to inclined travel surface (use gross-weight)
Rolling Resistance (RR)
Resistance due to tire flexing and roadway penetration (use weight-on-wheels)
Project Development
Selection of A/E, preliminary design, intermediate design, final design, bidding (selection of GC), construction phase, operations and maintenance,
Underground
Soils, groundwater/water table, utilities, subsurface conditions
Space Construction
Space laboratories, space habitat, lunar construction
Swinging Leads
Top and bottom of leads are not fixed
On the Ground
Traffic, accessibility, street restriction, grade and ramp, location of site office, material storage, site for equipment, safety and security (fences, barricades, temporary shelter, flood light, generators)
Underground Construction
Tunnels and underground facilities
Reciprocating (Piston) Air Compressor
Use crankshaft-driven piston - Piston compressed fluid (air) inside compression cylinder - Piston works in reciprocating fashion, hence its name - Compressed air produces high-pressure gas -Used in factories and plants
Centrifugal (Radian) Air Compressor
Use rotary positive displacement screw - Centrifugal impeller to rotate blades/vanes - Increase flow energy by increasing radius - Converting kinetic energy to potential energy (air flow slowed down to static air pressure) - Use for gas turbine and turbomachineries
Rotary Air Compressor
Use rotary positive displacement screw - Helical screws replace piston - Continuous sweeping motion, hence smoother air flow - Lighter - Reduce noise - Use for jackhammers, nailguns
Other Trends
Value Engineering, Partnering, Quality Assurance and Quality Control (QA/QC), Quantity Surveyor
Conical Spoil Pile
Volume = (1/3) * Base Area * Height
Triangular Prism (Spoil Bank)
Volume = 0.5 * Width * Height * Length
Plastic Limit (PL)
Water content at which soil start to become solid when rolled into 1/8 inches in diameter
Liquid Limit (LL)
Water content at which soil starts to become liquid
Subs/specialty contractors
excavation firms, highway pavement companies, concrete contractors, steel erectors, HVAC, electricians