Construction Process PDF

INTRODUCTION ENGR. MARK ANDREW M. ALINGOG The construction industry is one of the largest commercial activities in the Philippines, encompassing establishments engaged in the construction of buildings and larger engineering projects, such as roadways and utility infrastructure. Construction with a...

INTRODUCTION ENGR. MARK ANDREW M. ALINGOG The construction industry is one of the largest commercial activities in the Philippines, encompassing establishments engaged in the construction of buildings and larger engineering projects, such as roadways and utility infrastructure. Construction with all of its related and supporting industries has always played a vital role in the nation’s economy, accounting for around 16% percent of the gross domestic product. The process by which a building or other project is designed and constructed can be divided into four discreet project phases. The pre-design phase sets the initial objectives and criteria under which a building will be planned. The design phase determines the actual geometry, materials, and performance characteristics of the finished structure. The pre-construction phase selects the various project participants and outlines their contractual agreements. Finally, the construction phase is involved with the physical realization of the finished building. After the execution of an agreement, the construction stage of a project involves the contractors planning, administration, and completion of the actual construction of the final building. The notice to proceed is a written directive from the owner to the contractor that sets the date that the contractor can begin the work under the conditions of the contract. The directive identifies the contract delivery method and establishes the start of the construction schedule. The members of the design team are typically responsible for monitoring the contractor’s compliance with the contract documents by conducting site visits, evaluating submittals, reviewing requests for contract changes or substitutions, and certifying applications for payments. The construction phase typically ends when the owner submits the final payment to the contractor. During the construction phase of a project, the contractor is the primary participant of the ongoing work. Construction Scheduling Project scheduling is used to match the resources of equipment, materials, and labor with the project construction phases over time. It indicates the estimated start and completion dates of various components, establishing milestones and sequences that help in coordinating the numerous subcontractors on the site. Poor scheduling can result in considerable waste as workers and equipment wait for needed resources or the completion of preceding tasks by other trades. The most widely used scheduling technique is the critical path method (CPM) for scheduling, sometimes referred to as “critical path scheduling.” Permitting Prior to any work commencing on site, the constructor must secure a variety of regulatory permits. The building permit is a certificate issued by the local governing authority having jurisdiction (AHJ) authorizing the construction of a project after a thorough review of the construction documents to ensure compliance with local building, safety, and fire codes. The building permit must be posted in a clearly visible location until the project is completed (Figure 1.17). Specialty subcontractors are responsible for securing permits to allow their own portion of the work to proceed. Pre-Construction Planning and Temporary Facilities Once a building permit has been secured and the contract between the owner and contractor is signed, the actual on-site construction can begin. The formal notice to proceed indicates that all pre-construction requirements have been met. On larger projects, the general contractor may be required to establish a field office on the construction site. Field offices are often housed in mobile trailers that are fully furnished and provided with modern communication equipment. Shop Drawings, Submittals, and Mock-Ups While the construction documents give detailed information as to how components and assemblies will be constructed, other more specific drawings are required on most projects. A shop drawing gives precise directives for the fabrication of certain components, such as structural steel work, concrete reinforcing, or pre-cast concrete components. It is generated to explain the fabrication and sometimes installation procedures of the items to the manufacturer’s production crew or contractor’s installation crews. Construction Observation In addition to ongoing inspections by local building department officials, continuing inspections are conducted by representatives of the owner to ensure that the completed work complies with the guidelines set forth in the construction documents. In most contracts, this responsibility is held either by the architect or construction manager, who will visit the site periodically and prepare written reports to document adherence to the project schedule and keep the owner updated on the progress of the work. Near the end of a project, the contractor will request an inspection to document that the work has arrived at a point of substantial completion, indicating that the building is ready to be occupied by the owner. Contractor Requests for Information (RFI) During the construction process, it is not uncommon for the contractor to encounter portions of the work for which the contract documents do not provide clear and comprehensive directives. The request for information (RFI) is used by the contractor to obtain clarification on specific components and assemblies that are not fully detailed or understood through a comprehensive review of the drawings and specifications. Modifications to the Construction Contract Almost every construction project encounters conditions that require a change to be made to the original contract documents. Changes may be required for a number of reasons, including newly discovered conditions, design omissions or errors, or changes in the scope of the work. Project Close Out Prior to all construction being concluded, a number of administrative benchmarks must be met to complete the contractual obligations between the owner and the contractor. When the contractor determines that the work is nearing completion, the architect or construction manager is asked to return to the site and conduct an inspection of substantial completion. The inspection occurs at a point when all major portions of the work have been completed but a number of final details have yet to be finished. A listing of the remaining items to be installed or repaired is called a punch list. The punch list is initially prepared by the contractor and then added to by the architect and engineering consultants during their inspections. Construction Safety Throughout any construction project, a thorough accident prevention and safety training program must be implemented and maintained. The construction industry has one of the most hazardous work environments in the country, accounting for hundreds of fatalities and countless injuries each year. In 1970, the U.S. Congress passed the Williams-Steiger Occupational Health and Safety Act (OSHA) that initiated the regulation of safety standards for the construction industry. OSHA develops safety guidelines and administers their enforcement through a system of recurring site inspections. OSHA Standards-29 CFR–1926 Safety and Health Regulations for Construction, give extensive guidelines for construction means, methods, and materials handling. Density It is the mass of a unit volume of homogeneous material denoted by Bulk Density It is the mass of a unit volume of material in its natural state (with pores and voids) calculated as Density Index It indicates the degree to which the volume of a material is filled with solid matter. For almost all building materials density index is less than 1.0 because there are no absolutely dense bodies in nature. Specific Weight It is also known as the unit weight) is the weight per unit volume of material, Specific Gravity Specific Gravity of solid particles of a material is the ratio of weight/mass of a given volume of solids to the weight/mass of an equal volume of water at 4°C. Porosity is the degree to which volume of the material of the material is interspersed with pores. It is expressed as a ratio of the volume of pores to that of the specimen. Void Ratio It is defined as the ratio of volume of voids (Vv) to the volume of solids (Vs). Hygroscopicity is the property of a material to absorb water vapour from air. It is influenced by air-temperature and relative humidity; pores— their types, number and size, and by the nature of substance involved. Water Absorption the ability of the material to absorb and retain water. It is expressed as percentage in weight or of the volume of dry material: Weathering Resistance is the ability of a material to endure alternate wet and dry conditions for a long period without considerable deformation and loss of mechanical strength. Water Permeability is the capacity of a material to allow water to penetrate under pressure. Materials like glass, steel and bitumen are impervious. Heat Conductivity is the ability of a material to conduct heat. It is influenced by nature of material, its structure, porosity, character of pores and mean temperature at which heat exchange takes place. Thermal Capacity is the property of a material to absorb heat described by its specific heat. Fire Resistance is the ability of a material to resist the action of high temperature without any appreciable deformation and substantial loss of strength. Refractoriness denotes the ability of a material to withstand prolonged action of high temperature without melting or losing shape. Materials resisting prolonged temperatures of 1580°C or more are known as refractory. High-melting materials can withstand temperature from 1350– 1580°C, whereas low-melting materials withstand temperature below 1350°C. Chemical Resistance is the ability of a material to withstand the action of acids, alkalis, sea water and gases. Natural stone materials, e.g. limestone, marble and dolomite are eroded even by weak acids, wood has low resistance to acids and alkalis, bitumen disintegrates under the action of alkali liquors. Durability is the ability of a material to resist the combined effects of atmospheric and other factors. Strength is the ability of the material to resist failure under the action of stresses caused by loads, the most common being compression, tension, bending and impact. Hardness is the ability of a material to resist penetration by a harder body. Mohs scale is used to find the hardness of materials. Elasticity is the ability of a material to restore its initial form and dimensions after the load is removed. Within the limits of elasticity of solid bodies, the deformation is proportional to the stress. Plasticity is the ability of a material to change its shape under load without cracking and to retain this shape after the load is removed. Brittleness When the material is subjected to load, if it fails suddenly without causing any deformation then it is called brittle material and this property is called as brittleness. Fatigue If a material is subjected to repeated loads, then the failure occurs at some point which is lower than the failure point caused by steady loads.