CONSTRUCTION MANAGEMENT - Case study: Stoke-on-Trent Schools, UK

In 1997 many of the schools in Stoke-on-Trent were in a dilapidated state and not fit for modern teaching and learning practice. The schools included buildings dating back to the nineteenth century, some of which had not been upgraded or refurbished for 50 years. Furthermore, the annual budget for maintenance of all the schools was £120,000; totally inadequate when one large replacement boiler would cost £80,000. The City Council’s annual expenditure was already stretched to its absolute limit so a radical brave new way of thinking was required.

In November 2000, after three years of intense planning and negotiation, one of the first PFI partnership charters in the UK was signed to cover the refurbishment and maintenance for 25 years of all Stoke-on-Trent’s 122 schools. This five-year capital expenditure scheme was very much a pioneer in PFI school projects. There was no precedence to follow and no standard contracts were available at the time. It is noted that the Treasury Task Force later issued guidance for standardizing the terms of PFI contracts.

The project cycle followed the 4ps process with independent Gateway Reviews at key points, all as the OGC Gateway Process model (www.ogc.org.uk). The different procurement options were considered before selecting the PFI approach. Feasibility studies were undertaken using the public sector comparators as the benchmark. Output specifications were developed embracing such issues as minimum temperature in classrooms. Sophisticated financial models, which included sinking funds and risk allowances, were developed and rigorously tested.

The winning bid was received from a special-purpose company called Transform Schorest of the portfolio. One of the principal reasons that Balfour Beatty succeeded in securing the contract was its innovative proposal to replace nine schools rather than refurbish them. Once the SPV was chosen there was a 12-month intense period of activity in which the architects Aedas worked with the school governors to develop acceptable designs. The construction contracts were let on a design and build basis.

The PFI Board, comprising City Counsellors, representatives from the Department for Education and Skills (DfES) and 4ps together with the authority’s project director, met on a monthly basis. The PFI team comprising the authority’s project director, lawyers, financiers and the technical team met on a two-weekly basis. Some meetings comprised over 40 participants so one of the biggest challenges facing the project team was capturing the knowledge and expertise and incorporating the feedback into the project.

The key lessons learned from this project include the following:

 A real belief in the partnering ethos by all the parties. There were difficult problems to resolve throughout the negotiation period but the parties kept talking until these were finally resolved. The original contract, with 9 new schools, was extended to a total of 17 new schools; 15 were built by the SPV contractor and 2 by other contractors.

 Detailed identification and evaluation of the main risks throughout the 25-year period to be passed to the SPV. In this contract, the additional risks were estimated at 17%. Some risks were considered unreasonable for the SPV to carry and were retained by the authority, for example vandalism in school time.

 The importance of teamwork with the complete integration of the key stakeholders in an open forum.

Attention to detail in the innovative contract which included
a. a clause requiring the contractor to demonstrate a 20% saving in energy consumption in each school in the first five years by 2006 and a further 5% saving by 2010;

b. an agreement on the refinancing provision with the authority retaining 25% of any profits; this was a particularly difficult point for the negotiation team with the SPV wanting to retain the whole benefit, while the authority wished to take a 50:50 split;

c. the client’s involvement in securing a quality design, for example, they could comment at the point of handover and the contractor might be required to make changes at their own expense if not acceptable;

d. a stipulation that at the end of the 25-year period the estate should be in a position where there would be no major repair necessary for the next five years;

e. change or variation clauses allowing the authority to bring in other contractors to do the work if the SPV contractor’s price for the variation was considered too high.

This pioneering PFI project not only provided one of the best portfolios of school buildings in England but also resulted in other positive features including employment of 500 local labour during construction; apprentices taken on by the SPV contractors and sponsorship of a local community football team. Most significantly, there has been a dramatic reduction in school vandalism and a raising of student and teaching staff morale. It is anticipated that the improved buildings will also result in improved student performance in the years to come.

The main parties involved in this pioneering project were as follows:ols (Stoke) comprising shareholders Balfour Beatty Capital Projects (50%) and Innisfree (50%). The project is unique in being the largest bundled refurbishment scheme ever attempted in England and is valued at £153 million of which £80 million is for building nine new schools and refurbishing the assessments), Hurst Setter (health and safety), Capita (M&E and structural ), Walker Cotter (planning supervisor) and Atkins Faithfull & Gould (monitoring engineer/technical advisor to the lending banks);

Service Provider: Transform Schools (Stoke) Limited; Shareholders (providing the equity): Balfour Beatty Capital Projects 50% Innisfree 50%; Funders (providing the senior debt funding): Lloyds TSB and Dexia Public Finance Bank; Subcontractor 1: Stoke Schools JV comprising Balfour Kilpatrick Limited (Design and Build) and Balfour Beatty (Design and Build); Subcontractor 2: Haden Building Management Limited (Hard FM).

LOW SLOPE ROOFS BASIC INFORMATION AND TUTORIALS

COMPONENTS OF LOW SLOPE ROOFS


Low-slope roofs can have slopes as minor as 1⁄8 inch per 12 inches. These roofs employ a waterproof roofing system and are found primarily on commercial structures.

A low-slope roof system generally consists of a roof membrane, insulation, and one of a number of surfacing options. To control the application and improve the quality of low-slope roofing, a variety of specifications and procedures apply to the assembly of the roofing components.

These specifications and procedures are generally accepted and used throughout the United States. Roofing systems that meet these specifications normally can be expected to give satisfactory service for many years.


Climatic conditions and available materials dictate regional low-slope procedures, which can vary greatly in different parts of the country. Low slope roofs are essentially a custom product. They are designed for a specific building, at a specific location, and manufactured on the jobsite.


Membrane Components
Low-slope membranes are composed of at least three elements: waterproofing, reinforcement, and surfacing. Some materials within the membrane might perform more than one function. The waterproofing agent is the most important element within the roof membrane.

In BUR and modified bitumen roofing (MBR), the waterproofing agent is bitumen. In single-ply roofing, the waterproofing agent is synthetic rubber or plastic.

The reinforcement element provides stability to the roof membrane; it holds the waterproofing agent in place and provides tensile strength. In BUR, reinforcement is typically provided by organic or glass-fiber roofing felts. In MBR, the reinforcement is generally glass-fiber felt or polyester scrim, which is fabricated into the finished sheet by the manufacturer.

Polyester and other woven fabrics are used as reinforcements for elastomeric and plastomeric, single-ply membranes. Some singleply membranes do not require reinforcement because the waterproofing material is inherently stable.

The surfacing materials protect the waterproofing and reinforcement elements from the direct effects of sunlight and weather exposure. They also provide other properties, such as fire resistance, traffic and hail protection, and reflectivity.

Some single-ply membranes are self- or factory-surfaced. Aggregate, which is field-applied, and mineral granules, which are usually factory-applied, are the most common types of surfacing materials. Smooth-surfaced coatings, however, are increasing in popularity.


Membrane Classifications
Low-slope roof membranes can usually be grouped, or classified, into the general categories reviewed below. There are, however, hybrid systems that might not fit into a category, or that might be appropriate in several categories.

BUILT-UP ROOFING (BUR)
BUR, which uses asphalt or coal tar products, is by far the oldest of the modern commercial roofing methods. Many commercial buildings in this country have BUR roofs. The large number of 20-, 30-, and even 40-year-old BUR roofs that are still sound attests to the system’s durability and popularity.

Roofing materials continue to evolve, however, and improvements are continually being made to asphalt and coal tar pitch, the basic bitumen components of BUR. Asphalt tends to be more popular with most roofers than coal tar.

MODIFIED BITUMEN ROOFING (MBR)
Since the first MBR membranes were manufactured in the United States in the late 1970s, they have become one of the roofing industry’s fastest-growing materials. The popularity and specification of MBR membranes has increased steadily for more than two decades. Contractors have found the materials easy to use and easily inspected. MBR systems provide a time-tested, high-performance, reliable roof.

SINGLE-PLY SYSTEMS
Since they first appeared in the 1950s, single-ply materials have become increasingly popular in the United States. Whether imported from Europe or produced domestically, these high-tech products have proven themselves in a wide variety of climates during more than three decades of use.

WHAT IS THE DIFFERENCE BETWEEN AN ENGINEER AND AN ARCHITECT?

The major distinctions between architects and engineers run along generalist and specialist lines. The generalists are ultimately responsible for the overall planning.

It is for this reason that an architect is generally employed as the prime professional by a client. On some special projects, such as dams, power plants, wastewater treatment, and research or industrial installations, where one of the engineering specialties becomes the predominant feature, a client may select an engineering professional or an E/A firm to assume responsibility for design and construction and taken on the lead role.

On certain projects, it is the unique and imaginative contribution of the engineer that may make the most significant total impact on the architectural design.

The overall strength of a dynamic, exposed structure, the sophistication of complex lighting systems, or the quiet efficiency of a well-designed mechanical system may prove to be the major source of the client’s pride in a facility. In any circumstance, the responsibilities of the professional engineer for competence and contribution are just as important to the project as those of the
architect.

Engineers, for example, play a major role in intelligent building system design, which involves mechanical-electrical systems. However, a building’s intelligence is also measured by the way it responds to people, both on the inside and outside.

The systems of the building must meet the functional needs of the occupants as well as respect the human response to temperature, humidity, airflow, noise, light, and air quality. To achieve the multifaceted goals, an intelligent building requires an intelligent design process with respect to design and system formulation as well as efficient and coordinated execution of design and technical documentation within the management structure.

An intelligent building begins with intelligent architecture—the shape, the building enclosure, and the way the building appears and functions. Optimal building solutions can be achieved through a design process that explores and compares varying architectural and engineering options in concert.

Sophisticated visualization and analytical tools using three-dimensional computer modeling techniques permit architects and engineers to rapidly evaluate numerous alternatives. Options can be carefully studied both visually and from a performance standpoint, identifying energy and life-cycle cost impact. This enables visualization and technical evaluation of multiple schemes early in the design phase, setting the basis for an intelligent building.

In all cases, the architect’s or engineer’s legal responsibilities to the client remain firm. The prime professional is fully responsible for the services delivered. The consultants, in turn, are responsible to the architect or engineer with whom they contract.

Following this principle, the architect or engineer is responsible to clients for performance of each consultant. Consequently, it is wise for architects and engineers to evaluate their expertise in supervising others before retaining consultants in other areas of responsibility.

LUBRICATING OIL AGAINST CORROSION BASIC INFORMATION

Lubricants are not generally regarded as being corrosive, and in order to appreciate how corrosion can occur in lubricant systems it is necessary to understand something of the nature of lubricants. Once, lubricants were almost exclusively animal or vegetable oils or fats, but modern requirements in the way of volume and special properties have made petroleum the main source of supply. In volume, lubricants now represent about 2% of all petroleum products; in value, considerably more.

There are many hundreds of different varieties of lubricants, many of them tailored to meet particular requirements. Lubricating greases are solid or semi-solid lubricants made by thickening lubricating oils with soaps, clays, silica gel or other thickening agents. Synthetic lubricants, which will operate over a very wide range of temperature, have been developed mainly for aviation gas-turbine engines.

These are generally carboxylic esters and are very expensive products. The main function of most lubricants is to reduce friction and wear between moving surfaces and to abstract heat. They also have to remove debris from the contact area, e.g. combustion products in an engine cylinder, swarf in metal-cutting operations.


Mineral lubricants may be distillates or residues derived from the vacuum distillation of a primary distillate with a boiling point range above that of gas oi1’*2*T3.h ey are mixtures of hydrocarbons containing more than about 20 carbon atoms per molecule, and range from thin, easily flowing ‘spindle’ oils to thick ‘cylinder’oils.

For hydrocarbons having the same number of carbon atoms per molecule, the higher the proportion of carbon to hydrogen, the more viscous the oil and the lower the viscosity index.


Distillate lubricating oils can be conveniently divided into three groups -low viscosity index oils (LVI oils), medium viscosity index oils (MVI oils) and high viscosity index oils (HVI oils). LVI oils are made from naphthenic distillates, with low wax contents so that costly dewaxing is not required.

MVI oils are produced from both naphthenic and paraffinic distillates; the paraffinic distillates have to be dewaxed. HVI oils are prepared by the solvent extraction and dewaxing of paraffnic distillates. Solvent extraction is a physical process which removes the undesirable constituents, thereby improving viscosity index and the oxidation and colour stability.

White oils are obtained by the more drastic refining of low viscosity lubricating oil distillates to remove unsaturated compounds and constituents that impart colour, odour and taste. They are usually solvent extracted and then repeatedly treated with strong sulphuric acid or oleum and alkali, and finally ‘clay’-treated to remove surface-active compounds.

Acid and clay treating is expensive and is being superseded by hydrofinishing, a catalytic hydrogenation
treatment. The residues from the vacuum distillation can also be refined to provide very viscous lubricants. The residues from paraffinic base oils are generally solvent extracted and dewaxed. The main use of these products (bright stocks) is as blending components for heavy lubricants.

Thus residues from naphthenic base oils, which are also used as blending components for heavy lubricants, are normally not extracted. The performance characteristics of a lubricating oil depend on its origin and on the refining processes employed, and in order to ensure consistent properties these are varied as little as possible. Some aero-engine builders insist on a complete re-evaluation of a lubricant, costing many thousands of pounds, whenever there is a change of source (crude) or refining process.

PROFESSIONAL AND BUSINESS REQUIREMENTS OF ARCHITECTS AND ENGINEERS BASIC INFORMATION AND TUTORIALS

This article is important for both the service provider and the client.

Management of the building process is best performed by the individuals educated and trained in the profession, that is, architects and engineers. While the laws of various states and foreign countries differ, they are consistent relative to the registration requirements for practicing architecture.

No individual may legally indicate to the public that he or she is entitled to practice as an architect without a professional certificate of registration as an architect registered in the locale in which the project is to be constructed.

This individual is the registered architect. In addition to the requirements for individual practice of architecture, most states and countries require a certificate of registration for a single practitioner and a certificate of authorization for an entity such as a corporation or partnership to conduct business in that locale.

An architect is a person who is qualified by education, training, experience, and examination and who is registered under the laws of the locale to practice architecture there. The practice of architecture within the meaning and intent of the law includes:

Offering or furnishing of professional services such as environmental analysis, feasibility studies, programming, planning, and aesthetic and structural design Preparation of construction documents, consisting of drawings and specifications, and other documents required in the construction process

Administration of construction contracts and project representation in connection with the construction of building projects or addition to, alteration of, or restoration of buildings or parts of building

All documents intended for use in construction are required to be prepared and administered in accordance with the standards of reasonable skill and diligence of the profession. Care must be taken to reflect the requirements of country and state statutes and county and municipal building ordinances.

Inasmuch as architects are licensed for the protection of the public health, safety, and welfare, documents prepared by architects must be of such quality and scope and be so administered as to conform to professional standards.

Nothing contained in the law is intended to prevent drafters, students, project representatives, and other employees of those lawfully practicing as registered architects from acting under the instruction, control, or supervision of their employers, or to prevent employment of project representatives from acting under the immediate personal supervision of the registered architect who prepared the construction documents.

APPLICATION AND STORAGE OF LIME BASIC INFORMATION AND TUTORIALS

After being processed, quicklime can generate many varieties of lime, such as quicklime powder, hydrated lime powder, lime cream, and lime paste. And different varieties have different purposes.

1. Lime Powder
Lime powder can be made into silicate products mixed with materials containing silicon. With water, pulverized lime can be molded by being mixed with fiber materials (such as glass fiber) or lightweight aggregate. Then, it can be carbonized artificially with carbon dioxide for carbonized lime board.

Carbonized lime board has a good processing property, suitable for the non-load-bearing inner partition and ceiling. Mixed with a certain percentage of clay, pulverized lime can generate limestone soil.

Triple-combined soil can be generated by mixing lime powder with clay, gravel, and slag. Lime soil and triple-combined soil are mainly used for foundation, bedding cushion, and roadbed.

2. Lime Paste
The aged lime paste or hydrated lime can turns into lime milk, diluted with water, as paint of internal and external walls and ceilings; if mixed with a certain amount of sand or cement and sand, it can be prepared into lime mortar or compound mortar for masonry or finishing; it can be used to paint inner walls or ceilings by being mixed with paper pulp and hemp fiber.

3. Storage of Lime
Quicklime will absorb the water and carbon dioxide in the air, generate calcium carbonate powder and lose cohesive force. Thus, when stored on construction site, quicklime should not be exposed to moisture, not be more, and not stay for a long time.

Moreover, the aging of lime will release a great amount of heat, so quicklime and inflammable matter should be stored separately in order to avoid fire. Usually quicklime should be stabilized immediately and the storage period should be changed into aging period.

ARC TYPES BRIDGES COMPARISON WITH OTHER BRIDGE TYPES

Comparison with Simple Spans.
Simple-span girder or truss construction normally falls within the range of the shortest spans used up to a maximum of about 800 ft. Either true arches under favorable conditions or tied arches under all conditions are competitive within the range of 200 to 800 ft.

(There will be small difference in cost between these two types within this span range.) With increasing emphasis on appearance of bridges, arches are generally selected rather than simple-span construction, except for short spans for which beams or girders may be used.


Comparison with Cantilever or Continuous Trusses.
The normal range for cantilever or continuous-truss construction is on the order of 500 to 1800 ft for main spans. More likely, a top limit is about 1500 ft. Tied arches are competitive for spans within the range of 500 to 1000 ft.

True arches are competitive, if foundation conditions are favorable, for spans from 500 ft to the maximum for the other types. The relative economy of arches, however, is enhanced where site conditions make possible use of relatively short-span construction over the areas covered by the end spans of the continuous or cantilever trusses.

The economic situation is approximately this: For three-span continuous or cantilever layouts arranged for the greatest economy, the cost per foot will be nearly equal for end and central spans. If a tied or true arch is substituted for the central span, the cost per foot may be more than the average for the cantilever or continuous types.

If, however, relatively short spans are substituted for the end spans of these types, the cost per foot over the length of those spans is materially reduced. Hence, for a combination of short spans and a long arch span, the overall cost between end piers may be less than for the other types. In any case, the cost differential should not be large.

Comparison with Cable-Stayed and Suspension Bridges.
Such structures normally are not used for spans of less than 500 ft. Above 3000 ft, suspension bridges are probably the most practical solution. In the shorter spans, self-anchored construction is likely to be more economical than independent anchorages.

Arches are competitive in cost with the self-anchored suspension type or similar functional type with cable-stayed girders or trusses. There has been little use of suspension bridges for spans under 1000 ft, except for some self-anchored spans.

For spans above 1000 ft, it is not possible to make any general statement of comparative costs. Each site requires a specific study of alternative designs.

ZONING CODES OF CIVIL ENGINEERING CONSTRUCTION PROJECTS BASICS

Like building codes, zoning codes are established under the police powers of the state, to protect the health, welfare, and safety of the public. Zoning, however, primarily regulates land use by controlling types of occupancy of buildings, building height, and density and activity of population in specific parts of a jurisdiction.

Zoning codes are usually developed by a planning commission and administered by the commission or a building department. Land-use controls adopted by the local planning commission for current application are indicated on a zoning map.

It divides the jurisdiction into districts, shows the type of occupancy, such as commercial, industrial, or residential, permitted in each district, and notes limitations on building height and bulk and on population density in each district.

The planning commission usually also prepares a master plan as a guide to the growth of the jurisdiction. A future land-use plan is an important part of the master plan. The commission’s objective is to steer changes in the zoning map in the direction of the future land-use plan.

The commission, however, is not required to adhere rigidly to the plans for the future. As conditions warrant, the commission may grant variances from any of the regulations.

In addition, the planning commission may establish land subdivision regulations, to control development of large parcels of land. While the local zoning map specifies minimum lot area for a building and minimum frontage a lot may have along a street, subdivision regulations, in contrast, specify the level of improvements to be installed in new land-development projects.

These regulations contain criteria for location, grade, width, and type of pavement of streets, length of blocks, open spaces to be provided, and right of way for utilities.

A jurisdiction may also be divided into fire zones in accordance with population density and probable degree of danger from fire. The fire-zone map indicates the limitations on types of construction that the zoning map would otherwise permit.

In the vicinity of airports, zoning may be applied to maintain obstruction-free approach zones for aircraft and to provide noise-attenuating distances around the airports. Airport zoning limits building heights in accordance with distance from the airport.

BUILDING GYPSUM CHARACTERISTICS BASIC INFORMATION

Compared with other binding materials, building gypsum has the following characteristics:

1. Fast Setting and Hardening
The setting time of building gypsum changes with the calcination temperature, grinding rate and impurity content. Generally, mixed with water, its initial setting needs just a few minutes at room temperature, and its final setting is also within 30min.

Under the natural dry indoor conditions, total hardening needs about one week. The setting time can be adjusted according to requirements.

If the time needs to be postponed, delayed coagulant can be added to reduce the solubility and the solution rate of building gypsum, such as sulfite alcohol wastewater, bone glue activated by borax or lime, hide glue, and protein glue; if it needs to be accelerated, accelerator can be added, such as sodium chloride, silicon sodium fluoride, sodium sulfate, and magnesium sulfate.

2. Micro-expansion
In the hardening process, the volume of building gypsum just expands a little, and there won’t be any cracks. Thus, it can be used alone without any extenders, and can also be casted into construction members and decorative patterns with accurate size and smooth and compact surface.

3. Big Porosity
After hardening, the porosity of building gypsum can reach 50%-60%, so its products are light, insulating, and sound-absorbing. But these products have low strength and large water absorption due to big porosity.


4. Poor Water Resistance
Building gypsum has low softening coefficient (about 0.2-0.3) and poor water resistance. Absorbing water, it.wil1 break up with the freeze of water. Thus, its water resistance and frost resistance are poor, not used outdoors.

5. Good Fire Resistance
The main component of building gypsum after hardcning is CaS04*2H20. When it contacts with fire, the evaporation of crystal water will absorb heat and generate anhydrous gypsum which has good thermal insulation. The thicker its products are, the better their fire resistance will be.

6. Large Plastic Deformation
Gypsum and its products have an obvious performance of plastic deformation. Creep becomes more serious especially under bending load. Thus, it is not used for load-bearing structures normally. If it is used, some necessary measures need to be taken

STEEP SLOPE ROOF STYLES BASIC INFORMATION

While low-slope roofs are generally limited to flat-roof styles and are seldom found on residential structures, steep-roof styles vary greatly.

Of the steep-roof styles, the gable roof is the most common. It has a high point, or ridge, at or near the center of the house or wing that extends from one end wall to the other.

The roof slopes downward from the ridge in both directions. This roof style gets its name from the gable, which is the triangular section of end wall between the rafter plate and the roof ridge.

The roof on one side of the ridge is usually the same size and slope as the roof on the other side. The gable roof of the saltbox house is an exception.

An architecture common in New England, the saltbox has different slopes and slopes of different lengths. A hip roof also has a ridge, but the ridge does not extend from one end of the roof to the other.

The lower edge of the roof, or eave, is at a constant height and the roof slopes downward to the eaves on all sides. The point where two roof surfaces meet at an outside corner is called a hip. The junction where two roof surfaces meet at an inside corner is called a valley.

A shed roof slopes in only one direction, like half a gable roof. The roof has no ridge and the walls that support the rafters are different heights. The shed roof has several variations. One is the butterfly roof, where two shed roofs slope toward a low point over the middle of the house.

In another variation, two shed roofs slope upward from the eaves, but do not meet at a ridge. The wall between the two roofs is called a clerestory, and is often filled with windows to let light into the interior
of the house.

A gambrel, or barn roof, has double slopes: one pair of gentle slopes and one pair of steep slopes. Like a gable roof, the gambrel roof slopes in both directions from a center ridge. At a point about halfway between ridge and eave, however, the roof slope becomes much steeper.

In effect, the lower slope replaces the upper exterior walls of a two-story house. It is common to add projections through the roof, called dormers, for light and ventilation.

Just as a gambrel roof is like a gable roof with two different slopes, a mansard roof is like a hip roof. From a shorter ridge, the roof drops in two distinct slopes to eaves that are the same height all the way around the structure.

Up to 40 percent of the building is roof with the mansard roof design. In addition to typical residential applications, mansard roofs are often used for apartment complexes, commercial buildings, and even institutions such as schools.

CIVIL ENGINEERING PROJECT PEER REVIEW BASIC INFORMATION AND TUTORIALS

The building team should make it standard practice to have the output of the various disciplines checked at the end of each design step and especially before incorporation in the contract documents.

Checking of the work of each discipline should be performed by a competent practitioner of that discipline other than the original designer and reviewed by principals and other senior professionals.

Checkers should seek to ensure that calculations, drawings, and specifications are free of errors, omissions, and conflicts between building components.

For projects that are complicated, unique, or likely to have serious effects if failure should occur, the client or the building team may find it advisable to request a peer review of critical elements of the project or of the whole project.

In such cases, the review should be conducted by professionals with expertise equal to or greater than that of the original designers, that is, by peers; and they should be independent of the building team, whether part of the same firm or an outside organization.

The review should be paid for by the organization that requests it. The scope may include investigation of site conditions, applicable codes and governmental regulations, environmental impact, design assumptions, calculations, drawings, specifications, alternative designs, constructibility, and conformance with the building program.

The peers should not be considered competitors or replacements of the original designers, and there should be a high level of respect and communication between both groups. A report of the results of the review should be submitted to the authorizing agency and the leader of the building team.

(‘‘The Peer Review Manual,’’ American Consulting Engineers Council, 1015 15th St., NW, Washington, D.C. 20005, and ‘‘Peer Review, a Program Guide for Members of the Association of Soil and Foundation Engineers,’’ ASFE, Silver Spring, MD.)

SPECIALTY CONTRACTORS IN CIVIL ENGINEERING PROJECTS BASIC INFORMATION AND TUTORIALS

A specialty contractor or subcontractor is a separate contractor hired by the prime contractor to perform certain portions of the work. The amount of work that the prime contractor will subcontract varies from project to project.

Some federal and state regulations limit the proportion of a project that may be subcontracted, but this is rarely the case in private work. There are advantages and disadvantages to using specialty contractors.

Trades such as plumbing, electrical, and heating and air-conditioning have a tradition of being performed by specialty contractors, due to their specialized nature and licensing requirements. However, specialty contractors can now be found who are capable of performing every aspect of the construction project.

Contractors today can construct entire projects without having any direct-hire craft personnel. The use of specialty contractors has gained popularity as a means to reduce risk and overhead; however, the contractor gives up a substantial amount of control when subcontracting the entire project.

If specialty contractors are to be used, the contractor must be certain to notify them early in the bidding period so that they have time to prepare a complete, accurate proposal. If rushed, the specialty contractor tends to bid high just for protection against what might have been missed.

The use of specialty contractors can be economical, but estimates still must be done for each portion of work. Even if the estimator intends to subcontract the work, an estimate of the work should be prepared. It is possible that the estimator will not receive proposals for a project before the bid date and will have to use an estimated cost of the work in totaling the proposal.

All subcontractors’ proposals are compared with the estimator’s price; it is important that a subcontractor’s price is neither too high nor too low. If either situation exists, the estimator should call the subcontractor and discuss the proposal with him.

The specialty contractor’s proposal is often phoned, faxed, or e-mailed into the general contractor’s office at the last minute because of the subcontractor’s fear that the contractor will tell other subcontractors the proposal price and encourage lower bids. This practice is commonly referred to as bid peddling or bid shopping and is highly unethical and should be discouraged.

To prevent bid shopping, specialty contractors submit their final price only minutes before the bids close, which leads to confusion and makes it difficult for the estimator to analyze all bids carefully. This confusion is compounded by specialty contractors who submit unsolicited bids. These bids come from specialty contractors who were not contacted or invited to submit a bid, but who find out which contractors are bidding the project and submit a bid.

Since these companies are not prequalified, there is an element of risk associated with accepting one of these bids. On the other hand, not using low bids from unsolicited subcontractors places the contractor at a price disadvantage.

In checking subcontractor proposals, note especially what is included and what is left out. Each subsequent proposal may add or delete items. Often the proposals set up certain conditions, such as use of water, heat, or hoisting facilities. The estimator must compare each proposal and select the one that is the most economical.

All costs must be included somewhere. If the subcontractor does not include an item in the proposal, it must be considered elsewhere. A tricky task for the prime contractor is the comparison of the individual subcontractor’s price quotes.

Throughout the estimating process, the prime contractor should be communicating with the specific subcontractors concerning the fact that they will submit a price quote and what scope of work is to be included within that quote. However, subcontractors will include items that they were not asked to bid and will exclude items that they were asked to bid.

A “bid tabulation” or “bid tab” is used to equalize the scope between subcontractors so that the most advantageous subcontractor’s bid can be included in the prime contractor’s bid.

MECHANICAL PROPERTIES OF ALUMINIUM AND ALUMINIUM ALLOYS

The compositional specifications for wrought aluminium alloys are now internationally agreed throughout Europe, Australia, Japan and the USA. The system involves a four-digit description of the alloy and is now specified in the UK as BS EN 573, 1995.

Registration of wrought alloys is administered by the Aluminum Association in Washington, DC. International agreement on temper designations has been achieved, and the standards agreed for the European Union, the Euro-Norms, are replacing the former British Standards.

Thus BS EN 515. 1995 specifies in more detail the temper designations to be used for wrought alloys in the UK. At present, there is no Euro-Norm for cast alloys and the old temper designations are still used for cast alloys.

In the following tables the four-digit system is used, wherever possible, for wrought materials.

Alloy designation system for wrought aluminium

The first of the four digits in the designation indicates the alloy group according to the major alloying elements, as follow:

1XXX aluminium of 99.0% minimum purity and higher

2XXX copper

3XXX manganese

4XXX silicon

5XXX magnesium

6XXX magnesium and silicon

7XXX zinc

8XXX other element, incl. lithium

9XXX unused

1XXX Group:

In this group the last two digits indicate the minimum aluminium percentage.

Thus 1099 indicates aluminium with a minimum purity of 99.99%. The second digit indicates modifications in impurity or alloying element limits. 0 signifies unalloyed aluminium and integers 1 to 9 are allocated to specific additions.

2XXX-8XXX Groups:

In these groups the last two digits are simply used to identify the different alloys in the groups and have no special significance. The second digit indicates alloy modifications, zero being allotted to the original alloy.

National variations of existing compositions are indicated by a letter after the numerical designation, allotted in alphabetical sequence, starting with A for the first national variation registered.

SOURCES OF ESTIMATING INFORMATION FOR CIVIL ENGINEERING PROJECTS

For matters relevant to estimating and costs, the best source of information is your historical data. These figures allow for the pricing of the project to match how the company actually performs its construction.

This information takes into account the talent and training of the craft personnel and the management abilities of the field staff personnel. In addition, it integrates the construction companies’ practices and methodologies.

This is why a careful, accurate accounting system combined with accuracy in field reports is so important. If all of the information relating to the job is tracked and analyzed, it will be available for future reference.

Computerized cost accounting systems are very helpful in gathering this information and making it readily available for future reference. See Construction Accounting and Financial Management by Steven J. Peterson for more information on managing construction accounting systems.

There are several “guides to construction cost” manuals available; however, a word of extreme caution is offered regarding the use of these manuals. They are only guides; the figures should rarely be used to prepare an actual estimate.

The manuals may be used as a guide in checking current prices and should enable the estimator to follow a more uniform system and save valuable time. The actual pricing in the manuals is most appropriately used in helping architects check approximate current prices and facilitate their preliminary estimate.

In addition to these printed guides, many of these companies provide electronic databases that can be utilized by estimating software packages. However, the same caution needs to be observed as with the printed version.

These databases represent an average of the methodologies of a few contractors. There is no simple way to convert this generalized information to match the specifics of the construction companies’ methodologies.

TYPES OF BIDS IN CIVIL ENGINEERING PROJECTS BASIC INFORMATION

Basically, the two bidding procedures by which the contractor gets to build a project for owners are as follows:

1. Competitive bidding

2. Negotiated bidding

Competitive bidding involves each contractor submitting a lump-sum bid or a proposal in competition with other contractors to build the project. The project may be awarded based on the price or best value.

When the project is awarded based on the price, the lowest lump-sum bidder is awarded the contract to build the project as long as the bid form and proper procedures have been followed and this bidder is able to attain the required bonds and insurance.

When the project is awarded based upon the best value, the proposals from the contractors are rated based on specified criteria with each criterion given a certain percentage of the possible points. The criteria may include review of the capabilities of the assigned project team, the company’s capabilities and its approach to the project (including schedule), proposed innovation, method of mitigating risk, and price.

The price is often withheld from the reviewers until the other criteria have been evaluated to prevent the price from affecting the ratings of the other criteria. Most commonly, the bids must be delivered to the person or place specified by a time stated in the instruction to bidders.

The basic underlying difference between negotiated work and competitive bidding is that the parties arrive at a mutually agreed upon price, terms and conditions, and contractual relationship. This arrangement often entails negotiations back and forth on virtually all aspects of the project, such as materials used, sizes, finishes, and other items that affect the price of the project.

Owners may negotiate with as many contractors as they wish. This type of bidding is often used when owners know which contractor they would like to build the project, in which case competitive bidding would waste time.

The biggest disadvantage of this arrangement is that the contractor may not feel the need to work quite as hard to get the lowest possible prices as when a competitive bidding process is used.

OVERVIEW OF EARTHQUAKE RISK CIVIL ENGINEERING CONTEXT BASIC INFORMATION AND TUTORIALS

The first step in understanding earthquake risk is to dissect the earthquake risk or loss process into its constituent steps. Earthquake risk begins with the occurrence of the earthquake, which results in a number of earthquake hazards.

The most fundamental of these hazards is faulting, that is, the surface expression of the differential movement of blocks of the Earth’s crust. Faulting can be a simple “mole-track” lateral movement, or a major vertical scarp, or may not even be visible.

In most cases, faulting is typically a long narrow feature, and therefore affects a relatively small fraction of the total affected structures and persons. Affecting a much greater number of structures and persons is shaking, which is typically the primary hazard due to earthquakes.

Depending on the earthquake, liquefaction, other forms of ground failure, tsunamis, or other types of hazards may be significant agents of damage. For various reasons, many buildings, portions of the infrastructure, and other structures cannot fully resist these hazards, and sustain some degree of damage.

Primary damage can vary from minor cracking to total collapse. Some building types are more vulnerable than others, but even when a building sustains no structural damage, the contents of the building may be severely damaged.

For certain occupancies, such as hospitals or emergency services dispatch centers, this damage to contents (laboratories, specialized machinery, communication equipment, etc.) can be very important. Additionally, these various kinds of primary damage can lead to other secondary forms of hazard and damage, such as releases of hazardous materials, major fires, or flooding.

Damage results in loss.

Primary loss can take many forms — life loss or injury is the primary concern, but financial loss and loss of function are also of major concern. The likelihood of sustaining a loss is termed risk . Primary losses lead to secondary forms of loss, such as loss of revenues resulting from business interruption and loss of market share and/or reputation.

QUANTITY ESTIMATING CIVIL ENGINEERING PROJECTS BASIC INFORMATION AND TUTORIALS

In Canada, parts of Europe, and on most road construction projects in the United States, the estimated quantities of materials required on the project are determined by a professional quantity surveyor or engineer and provided to the interested bidders on the project.

This is often referred to as a unit price bid. In this method of bidding, the contractors are all bidding based on the same quantities, and the estimator spends time developing the unit prices. For example, the bid may be $47.32 per cubic yard (cy) of concrete.

Because all of the contractors are bidding on the same quantities, they will work on keeping the cost of purchasing and installing the materials as low as possible.

As the project is built, the actual number of units required is checked against the original number of units on which the estimates were made. For example, the original quantity survey called for 715 linear feet (lf) of concrete curbing.

If 722 lf were actually installed, then the contractor would be paid for the additional 7 lf. If 706 lf were used, then the owner would pay only for the 706 lf installed and not the 715 lf in the original quantity survey.

This type of adjustment is quite common. When errors do occur and there is a large difference between the original quantity survey and the actual number of units, an adjustment to the unit price is made. Small adjustments are usually made at the same unit rate as the contractor bid.

Large errors may require that the unit price be renegotiated. If the contractor is aware of potential discrepancies between the estimated quantities and those that will be required, the contractor may price his or her bid to take advantage of this situation.

With a belief that the estimated quantities are low, the contractor may reduce his or her unit price to be the low bidder. If the assumption is true, the contractor has the potential to make the same profit by distributing the project overhead over a greater number of units.

SURVEYING CLASSIFICATION BASIC INFORMATION AND TUTORIALS

What Are The Classification Of Surveying?

Surveying may be classified on the following basis:

(i) Nature of the survey field

(ii) Object of survey

(iii) Instruments used and

(iv) The methods employed.

Classification Based on Nature of Survey Field

On this basis survey may be classified as land survey, marine or hydraulic survey and astronomical survey.

Land Survey. It involves measurement of various objects on land. This type of survey may be further classified as given below:

(a) Topographic Survey: It is meant for plotting natural features like rivers, lakes, forests and hills as well as man made features like roads, railways, towns, villages and canals.

(b) Cadestal Survey: It is for marking the boundaries of municipalities, villages, talukas, districts, states etc. The survey made to mark properties of individuals also come under this category.

(c) City Survey: The survey made in connection with the construction of streets, water supply and sewage lines fall under this category.

Marine or Hydrographic Survey. Survey conducted to find depth of water at various points in bodies of water like sea, river and lakes fall under this category. Finding depth of water at specified points is known as sounding.

Astronomical Survey. Observations made to heavenly bodies like sun, stars etc., to locate absolute positions of points on the earth and for the purpose of calculating local time is known as astronomical survey.

Classification Based on Object of Survey

On the basis of object of survey the classification can be as engineering survey, military survey, mines survey, geological survey and archeological survey.

(a) Engineering Survey: The objective of this type of survey is to collect data for designing civil engineering projects like roads, railways, irrigation, water supply and sewage disposals. These surveys are further sub-divided into:

Reconnaissance Survey for determining feasibility and estimation of the scheme.

Preliminary Survey for collecting more information to estimate the cost of the project, and

Location Survey to set the work on the ground.

(b) Military Survey: This survey is meant for working out plans of strategic importance.

(c) Mines Survey: This is used for exploring mineral wealth.

(d) Geological Survey: This survey is for finding different strata in the earth’s crust.

(e) Archeological Survey: This survey is for unearthing relics of antiquity.

Classification Based on Instruments Used

Based on the instruments used, surveying may be classified as:

(i) Chain survey

(ii) Compass survey

(iii) Plane table survey

(iv) Theodolite survey

(v) Tacheometric survey

(vi) Modern survey using electronic distance meters and total station

(vii) Photographic and Aerial survey

The survey is taught to students mainly based on this classification.

Classification Based on Methods Employed

On this basis surveying is classified as triangulation and traversing.

(i) Triangulation: In this method control points are established through a network of triangles.

(ii) Traversing: In this scheme of establishing control points consists of a series of connected points established through linear and angular measurements. If the last line meets the starting point it is called as closed traverse. If it does not meet, it is known as open traverse.

SURVEYING OBJECTS AND USES BASIC INFORMATION AND TUTORIALS

What Is Surveying and What Are The Objects And Uses Of Surveying?

Surveying is the art of making measurements of objects on, above or beneath the ground to show their relative positions on paper. The relative position required is either horizontal, or vertical, or both.

Less precisely the term Surveying is used to the measurement of objects in their horizontal positions. Measurements to deteremine their relative vertical positions is known as levelling.

OBJECT AND USES OF SURVEYING

As stated in the definition, object of surveying is to show relative positions of various objects of an area on paper and produce plan or map of that area. Various uses of surveying are listed below:

(i) Plans prepared to record property lines of private, public and government lands help in avoiding unnecessary controversies.

(ii) Maps prepared for marking boundaries of countries, states, districts etc., avoid disputes.

(iii) Locality plans help in identifying location of houses and offices in the area.

(iv) Road maps help travellers and tourist.

(v) Topographic maps showing natural features like rivers, streams, hills, forests help in planning irrigation projects and flood control measures.

(vi) For planning and estimating project works like roads, bridges, railways, airports, water supply and waste water disposal surveying is required.

(vii) Marine and hydrographic survey helps in planning navigation routes and harbours.

(viii) Military survey is required for strategic planning.

(ix) Mine surveys are required for exploring minearl wealth.

(x) Geological surveys are necessary for determining different strata in the earth crust so that proper location is found for reservoirs.

(xi) Archeological surveys are useful for unearthing relics of antiquity.

(xii) Astronomical survey helps in the study of movements of planets and for calculating local and standard times.

CAMBER DEFINITION BASIC INFORMATION AND TUTORIALS

What Are Cambers?

Camber is a curvature built into a member or structure so that when it is loaded, it deflects to a desired shape. Camber, when required, might be for dead load only, dead load and partial live load, or dead load and full live load. The decision to camber and how much to camber is one made by the designer.

Rolled beams are generally cambered cold in a machine designed for the purpose, in a large press, known as a bulldozer or gag press, through the use of heat, or a combination of mechanically applied stress and heat.

In a cambering machine, the beam is run through a multiple set of hydraulically controlled rollers and the curvature is induced in a continuous operation. In a gag press, the beam is inched along and given an incremental bend at many points.

There are a variety of specific techniques used to heat-camber beams but in all of them, the side to be shortened is heated with an oxygen-fed torch.

As the part is heated, it tries to elongate. But because it is restrained by unheated material, the heated part with reduced yield stress is forced to upset (increase inelastically in thickness) to relieve its compressive stress.

Since the increase in thickness is inelastic, the part will not return to its original thickness on cooling. When the part is allowed to cool, therefore, it must shorten to return to its original volume. The heated flange therefore experiences a net shortening that produces the camber.

Heat cambering is generally slow and expensive and is typically used in sections larger than the capacity of available equipment. Heat can also be used to straighten or eliminate warping from parts. Some of these procedures are quite complex and intuitive, demanding experience on the part of the operator.

Experience has shown that the residual stresses remaining in a beam after cambering are little different from those due to differential cooling rates of the elements of the shape after it has been produced by hot rolling. Note that allowable design stresses are based to some extent on the fact that residual stresses virtually always exist.

Plate girders usually are cambered by cutting the web plate to the cambered shape before the flanges are attached.

Large bridge and roof trusses are cambered by fabricating the members to lengths that will yield the desired camber when the trusses are assembled. For example, each compression member is fabricated to its geometric (loaded) length plus the calculated axial deformation under load. Similarly, each tension member is fabricated to its geometric length minus the axial deformation.