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26/09/2024 INTRODUCTION TO VARIOUS ALTERNATIVE METHODS OBJECTIVE: OF STRUCTURAL To understand the uses and...

26/09/2024 INTRODUCTION TO VARIOUS ALTERNATIVE METHODS OBJECTIVE: OF STRUCTURAL To understand the uses and applications of cast in place method CONSTRUCTION and other alternative prefab methods of structural construction. CONSTRUCTION METHOD The procedures and techniques utilized during construction. Construction operations are generally classified according to specialized fields. These include preparation of the project site, earth-moving, foundation treatment, teel erection, concrete placement, asphalt paving, and electrical and OVERVIEW: mechanical installations. Procedures for each of these fields are generally the same, oFOUNDATION SYSTEM even when applied to different projects, such oPRE-CAST CONCRETE as buildings, dams, or airports. Construction Industry is repeatedly oCAST-IN-PLACE CONCRETE criticized for being inefficient and slow to oPRE-STRESSED CONCRETE innovate. The basic methods of construction techniques, and technologies have changed a little since Roman times. But the application of innovation in the construction industry is not straight forward. What are the Different Methods of Construction? ALTERNATIVE BUILDING CONSTRUCTION SYSTEM The methods of construction have always been influenced by prevailing technology, techniques, skills, and even the political and economic climate. This is why eras are It covers a wide range of modern The adoption of an alternative characterized by certain construction trends as shown by the history of the buildings. techniques and practices that encompass construction method requires an Before the discovery of modern materials like stone and clay, buildings were even the latest developments in materials appropriate design, commitment from the made of leaves and branches. technology, design procedures, quantity whole project team, suitable procurement surveying, facilities management services, strategies, good quality control, There are different factors as to why you should choose certain construction methods, structural analysis, and design and appropriate training, and care namely: management studies. Incorporating commissioning. alternative construction methods into size of the building practice can increase levels of quality, location of the construction efficiency, safety, sustainability, and value purpose of the building for money. However, there is often a budget for the project conflict between traditional construction environmental factors methods and innovative new practices, and this is often blamed for the relatively slow Ancient humans built their homes to protect them from climate and the environment. rate of technology transfer within the The following are some of the methods of construction that evolved from that need. construction industry. 1  26/09/2024 TRADITIONAL CONSTRUCTION METHOD The construction industry in the Philippines TRADITIONAL MODERN CONSTRUCTION METHOD CONSTRUCTION METHOD ADVANCED MODERN CONSTRUCTION METHOD History of construction in the Philippines The bahay kubo and bahay na bato employ traditional post and lintel construction/ platform framing. The pre-Hispanic bahay kubo utilizes building materials that are abundant and immediately available (e.g. timber, bamboo, palm fronds and grass), creating a light structure suited to the tropics. The simple construction and use of local materials facilitate the dwelling’s easy reconstruction and/or repair following earthquakes, typhoons or floods. Foundation System 01 FOUNDATION SYSTEM The foundation system transfers the lateral loads on the superstructure to the ground. The horizontal component of these lateral forces is transferred largely through a combination of soil friction on the bottom of footings and the development of passive soil pressure on the sides of footings and foundation walls. Foundation systems are classified into two broad categories: ▪ shallow foundation ▪ deep foundation 2  26/09/2024 Shallow Foundation Shallow Foundation Shallow are employed when stable soil of adequate bearing capacity occurs relatively near the ground surface. They are placed directly below the lowest part of a superstructure and transfer building loads directly to the supporting soil by vertical pressure. The 2. Strip footings are the continuous Types of shallow footings spread footings of foundation walls. 1. Individual or isolated footings are spread footings supporting free- standing columns and piers. 3. Stepped footings are strip footings that change levels to accommodate a sloping grade and maintain the required depth at all points around a building. Shallow Foundation Shallow Foundation 5. Continuous footing supports a line of columns supports all of the columns by strips at 3. Combined footing supports two or more 4. Cantilevered footing may be used in place of columns. This type of footing is used where it is right angles to each other a combined footing under the same conditions. not possible to center the footing beneath its In this type of construction, the footings of the inverted slab or inverted tee supported column as in the case of columns exterior and interior columns are connected by located at or very near the property line. In a tie-beam or strap which is so extended to such case, the nearest interior column is support the exterior column. The top of the selected and a combined footing constructed beam or strap is usually placed level with the under both columns. The footing is so designed top of the footings. so that the center of gravity of the combined loads passes through the center of gravity of the footing area. Shallow Foundation Shallow Foundation 7. STEEL GRILLAGE FOUNDATION When it is desired to avoid the deep excavation required for concrete and masonry footings, and when the load has to be distributed over a wide 6. Mat or Raft Foundations Mat foundations, like continuous footings are used on soil of area of support, steel rails or beams are used to low bearing power where there is a tendency towards unequal settlement due to give the required moment of resistance with a unequal loading of soil. In this type of foundation all parts of the foundation are so tied minimum of depth. together so that they will act as one and assist each other in keeping level and plumb. For steel-grillage foundations the foundation bed should first be covered with a layer of concrete not less than 6” in thickness and so mixed and compacted as to be nearly impervious to moisture as possible. The beams are placed on this layer, the upper surface brought to a line and the lower flanges carefully grouted so as to secure an even bearing. Subsequently, concrete should be placed between and around the beams so as to permanently protect them. The beam must not be spaced so near as to prevent the placing of concrete between them. The clear space between the flanges of the top layer of beams should not be less than 2” and should be somewhat more for the lower layers. 3  26/09/2024 Deep Foundation Deep Foundation PILE FOUNDATION A pile foundation is a system of end bearing or friction piles, pile caps, and tie beams for transferring building loads down to a suitable bearing stratum. ▪ WOOD PILES ▪ CONCRETE PILES o PRE-CAST PILES o CAST-IN-PLACE PILES o STEEL PILES Deep foundations are employed when the soil underlying a shallow o COMPOSITE PILES foundation is unstable or of inadequate soil bearing capacity. They extend down through unsuitable soil to transfer building loads to a more appropriate bearing stratum of rock or dense sand and gravel well below the superstructure. Deep Foundation Foundation Wall CAISSON FOUNDATIONS Foundation wall provide support Caissons are cast-in-place, plain or reinforced for the superstructure above concrete piers formed by boring with a large and enclose a basement wall or auger or excavating by hand a shaft in the earth to a suitable bearing stratum and filling crawl space partly or wholly the shaft with concrete. For this reason they below grade. In addition to the are also referred to as drilled piles or piers. vertical loads from the superstructure, foundation walls must be designed and constructed to resist active earth pressure and anchor the superstructure against wind and seismic forces. REINFORCED CONCRETE COLUMNS 02 REINFORCED CONCRETE Short columns – occur when the Long columns – occur when the unsupported height is not greater unsupported height is more than than ten times the shortest lateral ten times the shortest lateral dimension of the cross section. dimension of the cross section. 4  26/09/2024 TYPES OF REINFORCED COLUMNS TYPES OF REINFORCED COLUMNS Composite Columns – where structural steel columns are embedded into the concrete core of a spiral column. Combined Columns – where structural steel is encased in concrete of at least 7 cm thick, reinforced with wire mess Tied Columns. These are columns Spiral Columns. These are columns surrounding the column at a distance of 3 cm inside the outer with longitudinal bars and lateral with longitudinal bars and closely face of the concrete cover. ties. The ratio of the effective spaced continuous spiral hooping. For cross-sectional area of vertical spiral columns, the ratio of the area of Lally Columns – are fabricated steel pipes provided with flat reinforcement to the gross column the vertical reinforcement to the gross area should not be less than 1% column area shall not less than 1% nor steel plates which holds a girder or girt, and is filled with grout nor more than 8%, and should more than 8%. The minimum number or concrete to prevent corrosion. consist of at least 4 bars of a of bars shall 6, and the minimum bar minimum size of #5. size shall #5. REINFORCED CONCRETE BEAMS REINFORCED CONCRETE BEAMS A beam may be defined as a structural member, resting on supports usually at its ends, which supports transverse loads. The loads that act on the beam, as well as the weight of the beam itself, tend to bend rather than lengthen or shorten it. A girder is a term applied to a beam that supports one or more smaller beams, as concentrated loads. BEAMS 03 PRE-STRESSED CONCRETE Simple Beams These are beams having a single span with a support at each end, there being no restraint at the supports. Cantilever Beams These are beams that are supported at one end only, or they may be that portion of beams projecting beyond one of its supports. Continuous beams These are beams resting on more than two supports. The term “semi-continuous” is also frequently used in reinforced-concrete. It refers to a beam having two spans with little or no restraint at the two extreme ends of the beam. The end span of a continuous beam, where little or restraint is provided at the end support, is referred to as a semi-continuous beam. 5  26/09/2024 LIVE LOAD VS. DEAD LOAD COMPRESSION VS. TENSION Pre-Tensioning Post-Tensioning Pre-tensioning is done in the factories thus Post-tensioning can be done in factories as suitable for precast construction works. well as on the site. In this type of concrete, the pre-stressing In this type of concrete, the strands are cables called the strands are tensioned enclosed within a duct in the form and then before casting the concrete and then concrete is cast. The process of tensioning concrete is cast enclosing the tensioned the strands is carried out after the concrete cables. attains its sufficient strength. The size of a member is not restricted, Small sections are to be constructed. long-span bridges are constructed by post- tensioning. Pre-tensioning members are produced in a Cables are used in place of wires and jacks mould. are used for stretching. The concrete is prestressed with tendons Prestressing is done after the concrete before it is placing in position. attains sufficient strength. In Pre-tensioning, steel wires are tensioned before concrete is Pre-tensioning is preferred when the Post-tensioning is preferred when the structural element is small and easy to placed and hardened. In Post-tensioning, steel wires are stretched transport. structural element is heavy. out once the concrete is settled and hardened. Large panel systems, frame systems, slab column systems with shear wall FLOOR SYSTEM AND SLAB SYSTEM 04 CAST-IN-PLACE CONCRETE 6  26/09/2024 SLAB A slab can be defined as a flat, horizontal structural element made of reinforced concrete that acts as a load distribution point; for example, the slab receives a load from the beams through the columns to the footings and ultimately to the soil below. Structures that bear loads are supported by slabs and structures which bear loads are supported by frames. o Flat Slab Slab construction differs from one method to another o Flat Plate depending on the type of slab to be constructed. Slabs can be used o Ribbed Slab for floors or roofs, depending on what they are used for. In o Waffle Slab contrast to the live load acting on the roof slabs, the living load o Lift Slab acting on the floor slabs is considerably greater. o Span-Stress Floor System o Slip Form Method Flat Slab Flat Slab A simple flat slab is typically reinforced by concrete and supported by caps and columns without beam support. The simple flat slab can be constructed easily and requires only a small amount of formwork. Thus, the building loads are transferred into the columns for an effective balance. These simple flat slabs are suitable for spans ranging from 6m-9m. The span here refers to the distance between the two intermediate supports of the given structure. Similarly, the flat slabs are the perfect option for live loads weighing around 7kN/m2. Ribbed Slab Flat Slab Plate A one-way joist floor slab consists A column head is the reinforced of a series of small, reinforced concrete enlargement at the top of concrete T beams that are the column, which acts as an integral connected with girders that in part of the system. These column turn carried by the building heads can be designed at any angle column. T beams are known as for architectural purposes. However, joists which are formed by if you need designs on the concrete, it setting steel pan at a constant is advisable to place the concrete at spacing. Concrete is cast between 45°on on both sides of the vertical those spacing to make those ribs column. and in this way, the slab also cast and the slab becomes the flange of T beam. 7  26/09/2024 Waffle Floor Slab Lift Slab Lift-slab is technique whereby concrete floor slabs are poured on the ground, one on top of the other, and then lifted into place on top of columns by hydraulic jacks. Used for very tall multistory buildings, this method offers substantial savings in formwork. A waffle slab is a two way concrete slab reinforced by ribs in two directions. Waffle slabs are able to carry heavier loads and span longer distances than flat slabs. Span-Stress Floor System Slip Form Method A construction method which utilizes span-stress prestressed T- Slipform construction technique Joist that can be used with filler is an alternative for blocks or collapsible steel forms, conventional formwork system or plywood forms. The system has which helps in continuous the stiffness of a conventional slab vertical and horizontal since the concrete was poured construction. The slipform helps monolithic and is connected with to conduct continuous pouring the structure by providing of the concrete to the moving connection reinforcement that will formwork. The process stops transfer the lateral forces to the only when the required length lateral load resisting members. of casting is completed. Flat Type WALL PANEL SYSTEM 8  26/09/2024 Flat Type Ribbed Type Ribbed Type Window Type Wall Type Tilt-up Wall Panel System 9  26/09/2024 Tilt-up Wall Panel System 05 PRE-CAST CONCRETE Elements in Precast Concrete Precast concrete members are manufactured in factory under controlled conditions to keep standard dimensions and tolerances. TYPE OF Structural elements used in the construction of precast concrete buildings include: CONNECTION: o Precast Concrete Wall o Beam to Column Connections o Precast Slab o Column to Floor Connection o Precast Beam and Girder o Panel to Panel Connection o Precast Columns o Precast Stairs Frame System Large Panel System It is suitable for the construction of Large panel systems are useful for car parks, stadia, and offices. the construction of apartments and Precast frames can be constructed hotels. It consists of large walls and using either linear elements or floor concrete panels connected in spatial beam-column sub the vertical and horizontal assemblages. Precast beam-column directions. Both horizontal and sub-assemblages have the vertical panels withstand gravity advantages that the connecting faces loads. There are three between the sub-assemblages can be arrangements of large panel system placed away from the critical frame based on wall layouts which include regions. However linear elements cross-wall system, longitudinal-wall are generally preferred because of system, two-way system. the difficulties associated with forming, handling and erecting spatial elements. 10  26/09/2024 Slab Column Systems with Shear Wall END OF PRESENTATION. In this system, gravity loads supported by slab-column structure whereas shear walls withstand lateral loads. There are two types of slab-column system with shear walls namely; lift slab system with walls and pre- stressed slab-column system. 11