Building Construction Methods

TECHNOLOGICAL UNIVERSITY OF THE PHILIPPINESCOLLEGE OF ARCHITECTURE AND FINE ARTS

Graphics DepartmentManila

ARCHITECTURE TECHNOLOGY 215LECTURE

PABLO G. PILAR JR.INSTRUCTOR

Building ConstructionThe process of preparing for and forming buildings and building systems. Construction starts with planning, design, and financing and continues until the structure is ready for occupancy.Far from being a single activity, large scale construction is a feat of human multitasking. Normally, the job is managed by a project manager, and supervised by a construction manager, design engineer, construction engineer or project architect. For the successful execution of a project, effective planning is essential. Those involved with the design and execution of the infrastructure in question must consider the environmental impact of the job, the successful scheduling, budgeting, construction site safety, availability and transportation of building materials, logistics, inconvenience to the public caused by construction delays and bidding, etc.

Building ConstructionBuilding construction is the process of adding structure to real property or construction of buildings. The vast majority of building construction jobs are small renovations, such as addition of a room, or renovation of a bathroom. Often, the owner of the property acts as laborer, paymaster, and design team for the entire project. However, all building construction projects include some elements in common – design, financial, estimating and legal considerations. Many projects of varying sizes reach undesirable end results, such as structural collapse, cost overruns, and/or litigation. For this reason, those with experience in the field make detailed plans and maintain careful oversight during the project to ensure a positive outcome.

Commercial building construction is procured privately or publicly utilizing various delivery methodologies, including cost estimating, hard bid, negotiated price, traditional, management contracting, construction management-at-risk, design & build and design-build bridging.

Building Construction

Residential construction practices, technologies, and resources must conform to local building authority regulations and codes of practice. Materials readily available in the area generally dictate the construction materials used (e.g. brick versus stone, versus timber). Cost of construction on a per square meter (or per square foot) basis for houses can vary dramatically based on site conditions, local regulations, economies of scale (custom designed homes are often more expensive to build) and the availability of skilled tradespeople. As residential construction (as well as all other types of construction) can generate a lot of waste, careful planning again is needed here.

Types of Construction Projects

In general, there are nine types of construction:

Residential building constructionLight commercial constructionMulti-family constructionHealth-Care constructionEnvironmental constructionIndustrial constructionCommercial building constructionInstitutional constructionHeavy civil construction

Each type of construction project requires a unique team to plan, design, construct and maintain the project.

Preparation of Building Plans & Documents

Briefly defined, construction plans consist of drawings, diagrams and notes, showing the layout of floors and uses; the elevations or views, cross section; specified materials, other relevant information about the structure. In general, building plans consists of the following:

a) Architectural Plans & Detail Drawingsb) Structural Design computations & Detail Drawingsc) Electrical Plans, Load Analysis, Computations and Riser Diagrams, Specificationsd) Plumbing Plans, Details of Septic Vault, Diagrams of Plumbing Lines, Specificationse) Mechanical Plans and Specifications, where requiredf) Others: Landscaping and Interior Designs, etc.

Documents forming part of the building plans such as: g) Construction Specificationsh) Bill of Materials & Cost Estimatesi) Structural Design & Analysisj) Application for construction permits & utilitiesk) Other supporting papers or clearances required by local government rules & regulations

The plans & companion documents are signed and dry sealed by the architect and the engineers who prepared them. The project owner must also sign them to signify his/her approval.

Team Players in the Planning &Construction of a Project

The principal players assuming lead roles in initiating a project & preparing their plans & implementing them are the following:

Project owner or ProponentArchitects, Engineers & ConsultantsContractor, Builder, Construction Manager or Administrator

Also playing supporting parts are financiers, real estate brokers, government regulatory agencies, manufacturers and distributors of construction materials and the construction workers.

The owner conceives the idea of constructing a building to serve a specific need or purpose. He also provides the fund to build it. The funding may come from the owner alone, or through a real estate loan or from investors.

The initial step in transforming the project into the project into concrete reality is for the owner to contract the services of licensed professionals –qualified by training and experience-to prepare the plans and the related documents.

Discussing the Project Requirements

Before work on the plans is started, the owner & the architect would first discuss the project program & requirements. The owner would specify the purpose of the building & enumerate the needs to be met & the objectives to be attained. He/She gives suggestions & insights for the architect to take into account in drawing the building plans.

In the project discussions, the owner lets the architect know the amount of the budget & source of funding for the construction & related works. The payment of fees & the schedule of releases for the architectural- engineering and the supervision and inspection services are agreed upon. These are put in writing and signed by all concerned parties.

Engineers & Consultants required in Preparing Building Plans

Aside from his regular staff consisting of draftspersons, architectural designers, estimators, specifications writers & administrative employees, the architect must also avail of the technical expertise of engineers & consultants to assist in producing all drawings and accompanying documents for a given project. Engineers/experts supplementing the regular work force of the architect’s office are the following:

Professional Electrical Engineer or Master Electrician-prepares, signs and dry- seals the electric plans; including the application for an electrical permit to be issued by the concerned government office and the utility company to supply electric power for the project.

Sanitary Engineer or Master Plumber-prepares, signs and dry-seals the plumbing plans; including the application for the plumbing permit from the concerned government unit.

Engineers & Consultants required in Preparing Building Plans

Civil-Structural Engineer-designs & computes the correct sizes for structural frames & other critical parts to achieve economy in the construction, strength, stability & safety of the building; signs & dry seals his work.

Mechanical Engineer-prepares plans for mechanical installation; signs and dry seals the plans and application for permit to place the equipment indicated in the drawings.

Geodetic Engineer-draws the lot plan based from the data on the OCT or TCT of the project site if not yet available; or surveys the land, computes boundaries and locates or relocates concrete lot monuments, signs and seals his work.

Other experts, if required by the nature of the project or by the owner are: Landscape Architects, Interior Designers, Environmental Planners; Geo-technical Engineers, etc.

Lot Plan and Location Map of the Project Site

The project owner-aside from giving the guidelines and requirements to be taken into account in drawing the plans-should also provide the architect with the information about the area, shape, boundaries and characteristics of the terrain on which the building will be erected. The ideal source of the required information is the lot prepared by a licensed geodetic engineer or land surveyor.On this plan are plotted the land monuments (represented by circles) and the bearings and distances of the boundaries based on the technical descriptions appearing on the Original Certificate of Title (OCT) or Transfer Certificate of Title (TCT) of the land.

The architect/project designer needs all the technical information about the lot/project site to help him determine the ideal size, shape, orientation and placement of the proposed structure when he prepares the site development plan for the project.

Location/Vicinity Map of the Project Site

The Lot Plan is prepared by the Geodetic Engineer on a prescribed drawing sheet. Among other standard drawings to be shown thereon is the Location or Vicinity Map where the exact position of the project site in a subdivision or community is pinpointed. Details shown on the location map are the lots, blocks and the network of roads in the area, etc.

The Site Development Plan

In the Site Development Plan, the position, shape and dimensions of the proposed project are shown. The improvement proposed to be introduced on the property are also indicated.

Inspection of the Project Site

To acquaint the architect with actual conditions of the project site, the project owner should invite and accompany him to inspect it. This will result in further exchange of views on how best to achieve their common goal before the plans are started. It will also enable the architect to evaluate the negative and positive features of the land and take them into consideration in developing the design and plans.

Preparation of the Preliminary StudiesThe development of the building designwell and plans generally comes in two stages.

In the first stage, the architect prepares presentation drawings reflecting his best concept of the project. The plans he produced must conform to the reasonable wishes of the project owners and the building laws and regulation; among other considerations.

The initial drawing produced-commonly called preliminary studies-are presented to the owner for his study and approval. A rough estimate of the project cost, which may be calculated based on the floor area of the proposed structure is also shown.

The drawings initially submitted to the owner usually consist of the perspective view of the proposed building that shows how it will look like when finished, the floor plans, site development plan, elevations or cross sections of the project.

The preliminary studies are rendered in black and white or in color, using manual drafting or by computer. Needless to say, the architect or designer would strive to produce well-laid out floor plans that will enable the building occupants to live in comfort within it, or perform efficiently the activities or work in the building. He/she would strive for aesthetically pleasing views of the building; and to make a convincing presentation of his/her ideas to elicit favorable reaction from the project owner or proponent.

If the owner is not satisfied with the preliminary plans & requests for changes, the architect will have to go back to the drawing board and make the desired revisions. He/She will present the new drawings to the owner for study and approval.

Concrete and Reinforced Concrete

Concrete is a mixture of sand, gravel, crushed rock or other aggregates held together in a rocklike mass with a paste of cement and water. Sometimes one or more admixtures are added to change certain characteristics of the concrete such as its workability, durability and time of hardening. As with most rock like substances, concrete has a high compressive strength and a very low tensile strength.

Reinforce Concrete is a combination of concrete and steel wherein the steel reinforcement provides the tensile strength lacking in the concrete. Steel reinforcing is also capable of resisting compression forces and is used in columns as well as in other situations to be described later.

Advantages of Reinforced Concrete as a Structural Material

1. It has considerable compressive strength as compared to most other materials.2. Reinforce concrete has great resistance to the actions of fire & water and, in fact, is the

best structural material available for situations where water is present. During fires of average intensity, members with a satisfactory cover of concrete over the reinforcing bars suffer only surface damage without failure.

3. Reinforce concrete structures are very rigid.4. It is a low-maintenance material.5. As compared with other materials, it has a very long service life. Under proper

conditions reinforce concrete structures can be used indefinitely without reduction of their load carrying abilities. This can be explained by the fact that the strength of concrete does not decrease with time but actually increases over a very long period, measured in years, due to the lengthy process of the solidification of the cement paste.

6. It is usually the only economical material available for footings, basement walls, piers and similar applications.

7. A special feature of is its ability to be cast into an extraordinary variety of shapes from simple slabs, beams and columns to great arches and shells.

8. In most areas concrete takes advantage of inexpensive local materials (sand, gravel, and water) and requires relatively small amounts of cement and reinforcing steel.

9. A lower grade of skilled labor is required for erection as compared to other materials such as structural steel.

Disadvantages of Reinforced Concrete as a Structural Material

1. Concrete has a very low tensile strength, requiring the use of tensile reinforcing.2. Forms are required to hold the concrete in place until it hardens sufficiently. In

addition, falsework or shoring may be necessary to keep the forms in place for roofs, walls and similar structures until the concrete members gain sufficient strength to support themselves. Formwork is very expensive. It costs run from one-third to to two-thirds of the total cost of a reinforced concrete structure, with average values of about 50%.

3. The low strength per unit of weight of concrete leads to heavy members. This becomes an increasingly important matter for long-span structures where concrete’s large dead weight has a great effect on bending moments.

4. Similarly, the low strength per unit of volume of concrete means members will be relatively large, an important consideration for tall buildings and long-span structures.

5. The properties of concrete vary widely due to variations in its proportioning and mixing. Furthermore, the placing and curing of concrete is not as carefully controlled as is the production of other materials such as structural steel and laminated wood.

REINFORCING STEEL

The reinforcing used for concrete structures may be in the form of bars or welded wire fabric. Reinforcing bars are referred to as plain or deformed. The deformed bars which have ribbed projections rolled onto their surfaces (patterns differing with different manufacturers) to provide better bonding between the concrete and the steel, are used for almost all applications.Instead of rolled-on deformations, deformed wire has indentations pressed into it. Plain bars are not used very often except for wrapping around longitudinal bars, primarily in columns.

AGGREGATES

The aggregates used in concrete occupy about three-fourths of the concrete volume. Since they are less expensive than the cement, it is desirable to use as much of them as possible. Both fine aggregates (usually sand) and coarse aggregates (usually gravel or crushed stone) are used. Any aggregate that passes a no. 4 sieve ( which has wires spaced ¼ in. on centers in each direction) is said to be a fine aggregate. Material of a larger size is coarse aggregate.

LOADSPerhaps the most important and most difficult task faced by the structural designer is the accurate estimation of the loads that may be applied to a structure during its life. No loads that may reasonably be expected to occur may be overlooked. After loads are estimated, the next problem is to decide the worst possible combination of these loads that might occur at one time.

LIVE LOADS

Live Loads are loads that may change in position and magnitude. Simply stated, all loads that are not dead load are live loads. Live loads that move under own power are said to be moving loads, such as trucks, people and cranes, whereas those loads that may be moved are movable loads such as furniture and warehouse materials. Other live loads include those caused by construction operations, wind, rain, earthquakes, blasts, soils, and temperature changes.

CONCRETEFor a concrete construction of any size, as concrete has a rather low tensile strength, it is generally strengthened using steel rods or bars (known as rebars). This strengthened concrete is then referred to as reinforced concrete. In order to minimise any air bubbles, that would weaken the structure, a vibrator is used to eliminate any air that has been entrained when the liquid concrete mix is poured around the ironwork. Concrete has been the predominant building material in the modern age due to its longevity, formability, and ease of transport. Recent advancements, such as insulating concrete forms, combine the concrete forming and other construction steps (installation of insulation). All materials must be taken in required proportions as described in standards.

The Materials in Concrete

Concrete is a mixture of cement paste, fine and coarse aggregates.The cement paste consists of cement and water which bind the fine and coarse aggregates.When the mixture has sufficiently set, it takes on the characteristics of hard stone.The fine aggregate in concrete should consist of natural sand or of inert materials with similar characteristics, having clean, hard and durable, grains, free from organic matters or loam.The coarse aggregate should consist of crushed rocks of durable and strong qualities, or clean and hard gravel. The size of the coarse aggregate varies from 20mm to 38mm (3/4 in. to 1-1/2 in.) diameter.Water to be used for mixing concrete should be clean and free from injurious amount of oil, acids, alkalis, salt and other organic matters.

Portland & Pozzolan Cements

Two widely used cement blends employed in the preparation of concrete in general construction :Portland cement has been defined as a hydraulic cement produced by pulverizing clinkers consisting essentially of hydraulic calcium silicates and usually containing calcium sulphate as an interground addition. There are five types of portland cement: Type I – The most widely used portland cement for buildings and is also the least costly. It reaches its full strength after 28 days.Type II – A moderate heat portland cement used for large concrete concrete pours where less heat is desired during the concrete set

Type III – This is a highly strength portland cement which gives more strength before 28 days than Type I.Type IV – Low heat portland cement like Type III that releases heat during the concrete set.Type V – A sulphate resisting portland cement. This is the most expensive cement.

Portland & Pozzolan Cements

Pozzolan cement has been defined as a hydraulic cement consisting of a mixture of portland cement and definite amounts of natural and artificial pozzolanic materials like volcanic tuff, shales, clay, fly ash, blast furnace, slag, burnt clay.Type P – Pozzolan cement used in general construction where high in initial strength of the concrete befre 28 days is not required. However, after 28 days, it meets the compressive strength to which it is designed.Type 1P – This type of pozzolan cement is an early strength cement and is required for more critical concrete works.

Admixtures in Cement

Admixtures may be added during the preparation of the concrete. These are substances mixed in concrete to impart certain desired qualities.Among such qualities are: to improve the workability of the concrete; to increase its waterproof characteristics; to harden its surface; to accelerate its set; etc.

Proportions in Concrete

Varying the amount of cement, fine and coarse aggregates and water in a given volume of concrete results in different strengths of the mixture. The quality of concrete to be used in a given project is specified in different ways such as: by its water-cement ratio; weight of a given volume; compressive strength after 28 days and by the fixed proportion of cement, fine and coarse aggregates, by volume, contained in the concrete mixture. Under the last method, the concrete mixtures are identified by “classes” in which each “class” contains a given proportion of cement, fine and coarse aggregates by volume, as shown below:

Class of concrete

Volume (cement, sand

& gravel)

Probable strength after

28 days

Class AA 1: 1-1/2: 3 4000-3500 psi

Class A 1: 2: 4 3000-2500 psi

Class B 1: 2-1/2: 5 2000-1500 psi

Class C 1: 3: 6 1000-500 psi

Class D 1: 3 ½: 7 Less than 500 psi

Foundation DesignFoundation is the base of any structure. Without a firm foundation, the structure cannot stand. That is the reason why we have to be very cautious with the design of foundations because our entire structure rests on the foundation.

The strength of the foundation determines the life of the structure. As we discussed in the earlier article, design of foundation depends on the type of soil, type of structure and its load.On that basis, the foundations are basically divided into Shallow Foundations and Deep Foundations.

Reinforced Concrete FootingsFooting comprises of the lower end of a column, pillar or wall which is enlarged with projecting courses so as to distribute load.Footings shall be designed to sustain the applied loads, moments and forces and the induced reactions and to ensure that any settlement which may occur shall be as uniform as possible and the safe bearing capacity of soil is not exceeded.In sloped or stepped footings, the effective cross-section in compression shall be limited by the area above the neutral plane, and the angle of slope or depth and location of steps should be such that the design requirements are satisfied at every section.

SKELETON PRESENTATION OF A TWO STOREY RESIDENCE