Construction PDF

Bubble diagrams are systems of lines and circles used in architecture to show relationships between functional areas of a program to develop an architectural plan Preliminary Drawing Preliminary designs are produced if a concept needs further resolution For the preliminary phase, the...

Bubble diagrams are systems of lines and circles used in architecture to show relationships between functional areas of a program to develop an architectural plan Preliminary Drawing Preliminary designs are produced if a concept needs further resolution For the preliminary phase, the main goal is to map out how the complex components will perform the functions in a given site, and their defined interfaces within the general environment Used to present to the client and the client assess how well the plan suits their needs and if any changes need to be made  Measure enough existing features to verify the scale of your drawings Overall length and height of building faces Location and width of paths Location & size of tress & shrubs Detailed Drawing Tender Issue Plan used to communicate the fully resolved design to the contractors Include all details that the contractors will need to provide an accurate quote : Scope of works to be done, the required components, estimate labor requirement Categories of Construction Owner, Occupancy, End Type Products: - Residential ,Industrial, Commercial,Infrastructure Fire Resistance : - Type I - Type II - Type III - Type IV - Type V Types of shallow foundation A combination of two or three types of shallow foundation in one single structure is not uncommon. Advantages Suitable for low rise building with relatively high column load Very economical compared to pile foundation Less excavation area (but deeper excavation required) Lesser reinforcement and concrete usage Uniform pad size may allow repetitious usage of formwork Disadvantages Require relatively high soil bearing pressure especially for 3-4 storeys building (75-150kN/m2 for 1-2 storey & 200-250kN/m2 for 3-4 storeys to become economical) May require protection to excavation work Deeper than 1.5m is not economical and dangerous May require dewatering (pumping out ground water) Wall/Strip Foundation is a continuous strip of concrete that serves to spread the weight of a load-bearing wall across an area of soil The footing usually has twice the width as the load bearing wall, sometimes it is even wider. Wall footings carrying direct vertical loads might be designed either in plain concrete or in reinforced concrete Advantages: Can be constructed shallower than pad foundation, less excavation Only one layer of reinforcement is required Suitable for low ground bearing pressure compared to pad foundation Suitable for linear load (load bearing wall) Disadvantages: Extra concrete volume compares to pad foundation Not suitable for supporting column with high load Not economical (in terms of excavation work) if the strip foundation is to be located deeper into ground. Combined footing If the base area is constraint by the boundary or by other adjacent closely spaced columns, then combining these isolated pads (hence the term ‘combined foundation’) may be solution. Consists of two or more columns over a single footing. A combined footing is classified as rectangular combined footings( columns carry equal load) and trapezoidal combined footings( one column carries heavier load) Strap footings consisting of two individual footings connected through a beam strap.  The strap beam, connecting the spread footing of the two columns, does not remain in contact with soil and thus does not transfer any pressure to the soil. These types of foundations are economical than combined footings. It is used to help distribute the weight of either heavily or eccentrically loaded column footings to adjacent footings Mat/Raft footings a large continuous rectangular or circular concrete slab resting on the soil and covering the total area of the proposed structure. it serves both as foundation and slab and does not require ground beams except at perimeter. Even the beams at perimeter are not structural beams. In broad terms, the raft foundation is designed to ‘float’ on poor ground while distributing local heavy loads which come down upon it, to an acceptable final ground pressure. are used when the building load is so high, that spread or strip footings could not bear the weight It is useful in controlling the differential settlement. Advantages: No ground beam construction except at perimeter (if required) due to significant difference between platform level and finished ground floor level Lesser usage of formwork at ground level, normally at perimeter or at drop area. Lesser excavation at ground level, no protection to excavation work. May reduce construction time because completion of raft foundation means completion of ground slab and ground beam. Most suitable for soil with low bearing capacity (about 30N/mm2) Disadvantages: Normally require two layers of reinforcement and this may increase construction cost. Not economical for medium rise structure (although adequate soil bearing can be achieved) because it will increase the raft thickness. Careful planning on the work sequence required where services of water, sewerage etc need to be laid under the raft. Maintenance of such services also becomes difficult after completion Normally requires construction joint (extra cost) Typical Failure of Foundations Strip foundations can fail due to cracking at their base induced by bending of the foundations, or due to shear cracking when it becomes overloaded. Underpinning A process of modifying, strengthening and reinforcing an existing foundation system by extending the depth and breadth of the foundation. by extending into subsurface stratum that is deeper and more stable than the near surface soil Main objective transfer the load carried by an existing foundation from its present bearing level to a new level at a lower depth. It also can be used to replace an existing weak foundation Uneven loading As a preliminary operation to lowering the adjacent ground level when constructing a basement at a lower level than the existing foundations. Unequal resistance of the subsoil Uneven settlement Action of subsoil water Cohesive soil settlement  To increase the load bearing capacity of the foundation – to enable an extra storey to be added to the existing structure or change of use would increase the imposed loading Mass Concrete Underpinning Beam and Base Underpinning Mini-piled Underpinning Deep Foundation Deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground. Deep foundation always refer to the usage of PILES and basically no excavation work required as inshallow foundation. Deep foundation – works on the basis of ground bearing and friction This is usually at depths >3 m below finished ground level. These foundations penetrate weak compressible soils until a satisfactory bearing stratum is reached. Rock stratum, firm sand/gravel that has been compacted Why? High water table Heavy point loads of the structure exceeding the soil capacity Presence of highly compressible soils near the surface such as filled ground and underlying peat strata Subsoil such as clay, which may be capable of moisture movement or plastic failure Low bearing capacity of the subsoil Advantages It can sustain the heavy load. We can construct high rise structures in low bearing capacity of the soil. Used to build large scale structures. It can resist the seismic load impact. Disadvantages The cost of deep foundation construction is high. Highly skilled manpower is required. Much more safety precautions required while execution. Potential Causes of Formwork Failures Improper stripping and shore removal Inadequate bracing Vibration : from passing traffic, moving of equipment Unstable soil/ground Inadequate control of concrete placement Lack of attention to formwork details Scaffolding A temporary structure for persons can gain access to high-level working areas in order to carry out building operation. A temporary structure created to support construction workers, inspectors, cleaners, and others who need to work at height. A temporary frame usually constructed from steel or aluminium alloy tubes clipped or coupled together to provide a safe platform to facilitate the construction, repair or maintenance when the work is to be carried out at height. Benefits of Scaffolding Long-lasting, Safety, Bridging, Access, Balance, Ease of construction Scaffolding Components: Base plate : A flat supporting plate or frame at the base of a column, designed to distribute the column's weight over a greater area and provide increased stability. mud sill under the scaffold base plate is to uniformly distribute the scaffold load over a larger area than that distributed by the base plate alone, thereby reducing the loading on the ground beneath the base plates. Standards: Also called uprights, are the vertical tubes that transfer the entire weight of the structure to the ground where they rest on a square base plate to spread the load. As standards are of fixed lengths, taller scaffolding requires that the pipes be connected so as to route the load directly through the structure. This is accomplished by way of a pin and socket joint which twists to lock successive pipes together. Ledgers: Tubes with a case wedge fixing device on their end that are positioned horizontally between two standards, defining the length of the scaffold bay. Multiple bays are connected with these ledgers both at the back and the front of the scaffold. Transoms/Putlog: Transoms or bearers, placed on top of ledgers and at right angles to them, run horizontally from back to front, defining the bay width. Main transoms provide support for standards by holding them in position as well as supporting boards or planks. Intermediate transoms are placed alongside main transoms to lend additional board support Platforms/Decking: During the working process, boarders serve as horizontal platforms for supporting workmen and materials. Scaffolds must be fully planked or decked whenever possible. may be made of solid sawn wood, manufactured wood, manufactured steel, or manufactured aluminum. If solid sawn wood is used, it must be scaffold grade. Couplers and clamps: fitting used in scaffolding used to join ledgers to standards, fixing putlogs/transoms to the horizontal ledgers Guardrail : A fall protection system (i.e. guardrail system) must be installed on all scaffolds with a working height greater than four feet. Rail provided at about 1 m level to guard the men working on the boarding Mid rails must be installed at a height approximately midway between the top rail and the platform surface. Toe boards: A parallel set of boards, placed parallel to boarding supported on putlogs, which provides protection at the working platform level. Toe boards must be installed not more than 1/4 inch above the platform and securely fastened Dangers associated with work on scaffolds Defects, Poor construction , Falling objects, Weather, Ignoring safety standards equipment ,Inadequate training ,Poor maintenance Construction 4.0 1. Pre-fabrication & Modular Construction: Involves assembling components of a structure in a factory or other manufacturing site and transporting complete assemblies or sub-assemblies to the construction site. This method increases efficiency, reduces waste, and can be more sustainable. 2. Advanced Building Materials: Refers to the use of innovative materials in construction, which may include self-healing concrete, high-performance insulation, or sustainable materials like bamboo, aimed at improving durability, energy efficiency, and reducing the environmental impact. 3. 3D Printing & Additive Manufacturing: Involves using 3D printing technology to create components or even entire buildings layer by layer. This method allows for more complex designs, reduced material usage, and potentially faster construction times. 4. Autonomous Construction: Utilizes robots, drones, or other automated machinery to perform construction tasks with minimal human intervention. This can improve safety, precision, and efficiency on construction sites. 5. Augmented Reality & Virtualization: Refers to the use of AR and VR technologies to visualize construction projects in real-time. This helps in planning, design, and communication by allowing stakeholders to see a project’s progress or potential outcomes before actual work begins. 6. Big Data & Predictive Analytics: Involves collecting and analyzing large amounts of data from construction projects to make informed decisions, predict outcomes, and optimize processes. This can lead to better resource management, reduced costs, and improved project timelines. 7. Wireless Monitoring & Connected Equipment: Refers to the use of IoT devices and wireless sensors to monitor various aspects of a construction project, such as equipment performance, site conditions, and worker safety in real-time. This ensures better coordination and efficiency. 8. Cloud & Real-Time Collaboration: Utilizes cloud computing to enable real-time collaboration among stakeholders, regardless of their physical location. This allows for instant access to project data, improved communication, and faster decision- making.  9. 3D Scanning & Photogrammetry: Involves capturing detailed 3D images of construction sites or buildings using laser scanning or photogrammetry. This data can be used for accurate measurements, progress tracking, and quality control. 10. Building Information Modeling (BIM): A digital representation of the physical and functional characteristics of a building. BIM is used to manage information throughout a building’s lifecycle, from design through construction to operation, and ensures better coordination among various stakeholders. Type of earth-retaining structures Gravity walls rely on their significant mass and geometrical dimensions for stability against, for example, sliding, overturning. Little or no contribution to stability is made from the passive resistance of any soil acting on the face of the wall. Gravity walls : Mass Construction They are the simplest and earliest recorded type of retaining wall, and are usually built of concrete, masonry, brick, blocks or mass cast-in-situ concrete. Gravity retaining walls are typically designed to be wider at their base, with sloped faces, enabling them to resist the higher lateral earth pressures at depth. Despite their advantages, gravity retaining walls are not suitable for retained heights above 3m. Gravity walls : Reinforced Construction built using reinforced concrete, with an L-shaped, or inverted T-shaped, foundation. This kind of retaining wall consists of a stem and a base slab (or footing) which sits under the backfill. T-shaped foundation benefits from the weight of soil (and therefore vertical stress) in front of the wall, providing further stability to the retaining structure. take up little space once built, and are suitable for retained heights of up to 5 m (cantilever) and 8-12 m (with counterfort/buttress) In-situ /Embedded walls : Embedded retaining walls extend deeper than the excavation to take advantage of passive earth pressure of the ground below to, at least partly, counteract the active earth pressure being exerted on the wall above. Additional support is provided to these retaining structures by internal propping – usually from the base slab, ground slab and any intermediate floor slabs – or by ground anchors installed through the wall. Is used to form near-surface underground structures, such as basements, car parks and metro stations. can be built using a number of different methods, depending on ground conditions, how watertight the excavation has to be, constructability (i.e. time, cost and excavation method) and the retained depth required. In-situ /Embedded walls : Sheet Pile Walls Sheet piles are tine, wide steel piles Driven to the ground using pile hammer Series of sheet piles in a row form a sheet pile wall Sheet pile retaining wall economical till height of 6m but it cannot withstand very high pressure In-situ /Embedded walls : Soldier Pile Walls Often used as temporary retaining structures for construction excavation Consist of a vertical wide flange steel members (spacing is commonly between 1.8 m to 2.45 m) with horizontal timber lagging. In-situ /Embedded walls : Slurry / Secant Pile Walls It is employed in both temporary and permanent works. can be exposed as a finished wall or have a sprayed concrete wall applied to the surface to achieve a more aesthetic and waterproof finish. Popular applications include beachfront scour protection walls and basement ‘groundwater cut-off’ walls. offer high stiffness retaining elements which are able to hold lateral pressure in large excavation depths with almost no disturbance to surrounding structures or properties Reinforced soil walls Reinforced soils are used: ✓ as an integral part of the design ✓ as an alternative to the use of reinforced concrete or other solutions on the grounds of economy or as a result of the ground conditions ✓ as remedial or improvement works to an existing configuration. Reinforced soil walls : Soil Nailing Ideal for sites that have loosely packed soil Involves long, steel reinforcement sinews that are inserted into the excavated or sloped soil, which essentially work in tension, called Passive Bars They are then cemented into place with a grout mixture to stabilize the soil and prevent it from collapsing or shifting This is ideal for applications such as: ✓ Temporary excavation for construction sites ✓ Tunnels, bridges, and roadways ✓ Remediation of failed retention walls Reinforced soil walls : Reinforced Earth Sometimes referred to as mechanically stabilized earth (MSE) walls It is among the most economical and most commonly retaining walls. Are constructed using geosynthetic soil reinforcements which are placed in layers within a controlled granular fill The layers of geogrid/geotextiles reinforce the soil into a stabilized mass, increases the bearing capacity of the retaining structure, along with its resistance to differential settlement Hybrid systems Retaining walls that use both mass and reinforcement for stability are termed as Hybrid or Composite retaining wall systems.