CSP115B - Week 4 Structures.pdf

Construction Principles CSP115B (Week 4 – Structures) Introduction to Structures Structures are the backbone of our built environment. They provide us with shelter, facilitate transportation, and support our daily lives in countless ways. From ancient monuments to modern skyscrapers, struct...

Construction Principles CSP115B (Week 4 – Structures) Introduction to Structures Structures are the backbone of our built environment. They provide us with shelter, facilitate transportation, and support our daily lives in countless ways. From ancient monuments to modern skyscrapers, structures have been a testament to human ingenuity and innovation. As civil engineers, you will learn to design, analyze, and build structures that are safe, efficient, and aesthetically pleasing. Faculty of Engineering and the Built Environment Department of Civil Engineering Introduction to Structures Structures can be broadly classified into two categories: non-building structures and building structures. Non-building structures include bridges, dams, towers, and pipelines, while building structures encompass residential, commercial, and industrial buildings. Each type of structure presents unique challenges and requires a deep understanding of materials, loads, and forces. As you delve into the world of structures, you'll discover the fundamental principles that govern their behavior. You'll learn about: Faculty of Engineering and the Built Environment Department of Civil Engineering Introduction to Structures Materials science: understanding the properties and behaviors of various materials. Statics and dynamics: analyzing forces, moments, and stresses. Strength of materials: determining the capacity of materials to withstand loads. Structural analysis: calculating stresses, strains, and deformations. Throughout your journey, you'll explore various types of structures, including beams, columns, trusses, arches, and frames. You'll learn to apply mathematical models, computational tools, and experimental techniques to design and optimize structures. Faculty of Engineering and the Built Environment Department of Civil Engineering Introduction to Structures Remember, building structures is not just about creating physical spaces; it's about crafting environments that inspire, connect, and protect people. As civil engineers, you have the power to shape the world around us. Embrace this challenge, and let's start building! Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering As civil engineers, you will encounter various structural forms that provide the foundation for buildings, bridges, and other infrastructure. Understanding these forms is crucial for designing and analyzing structures that are safe, efficient, and aesthetically pleasing. Let's explore some fundamental structural forms: Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) 1) Beams: Horizontal or sloping members that resist bending forces, commonly used in floors, roofs, and bridges. 2) Columns: Vertical members that resist compressive forces, often used in buildings and bridges. 3) Trusses: Triangular arrangements of members that resist compressive and tensile forces, commonly used in roofs, bridges, and towers. 4) Arches: Curved members that resist compressive forces, often used in bridges, tunnels, and buildings. 5) Frames: Assemblies of beams and columns that resist various forces, commonly used in buildings and bridges. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) Types of Beams Reinforced Concrete Columns Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) More Structural Forms: 1) Shells: Thin, curved surfaces that resist compressive and tensile forces, often used in domes, tanks, and roofs. 2) Catenaries: Curved members that resist tensile forces, commonly used in suspension bridges and cables. 3) Space Frames: Three-dimensional assemblies of members that resist various forces, often used in large-span structures like stadiums and airports. 4) Tensegrity Systems: Structures that use tension and compression to maintain stability, commonly used in innovative and futuristic designs. 5) Membranes: Thin, flexible surfaces that resist tensile forces, often used in tents, canopies, and inflatable structures. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) The steel gridshell by Vladimir Shukhov (during construction), Vyksa near Nizhny Novgorod, 1897 Tensegrity structure (a T3-prism) Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) A catenary cable vs. a cable with a parabola shape The difference of a catenary shape and a parabola Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) Understanding these structural forms will help you: - Analyze and design structures that meet specific requirements. - Select appropriate materials and construction methods. - Innovate and push the boundaries of engineering design. Faculty of Engineering and the Built Environment Department of Civil Engineering Building Structures: The Art of Creating Safe and Functional Spaces Building structures are complex systems that require careful consideration of various factors, including: 1) Loads: Dead loads (weight of materials), live loads (occupancy), wind loads, seismic loads, and snow loads. 2) Materials: Selection of appropriate materials, such as steel, concrete, wood, and masonry, based on strength, durability, and cost. 3) Structural Systems: Beams, columns, trusses, and frames work together to resist forces and support loads. Faculty of Engineering and the Built Environment Department of Civil Engineering Types of Building Structures 1. Low-Rise Buildings: One- to three-story buildings, often using wood, concrete or light steel framing. 2. Mid-Rise Buildings: Four- to ten-story buildings, commonly using steel or concrete framing. 3. High-Rise Buildings: Over ten stories, typically using steel or concrete framing with advanced structural systems. 4. Long-Span Structures: Large, open spaces like auditoriums, arenas, and shopping centers, requiring specialized structural solutions. Faculty of Engineering and the Built Environment Department of Civil Engineering Design Considerations 1. Sustainability: Energy efficiency, material selection, and waste reduction. 2. Aesthetics: Balancing functionality with visual appeal. 3. Safety: Ensuring occupant safety through fire resistance, emergency egress, and structural integrity. 4. Constructability: Designing for efficient construction, minimizing costs and delays. 5. Maintenance: Considering long-term maintenance and repair needs. Faculty of Engineering and the Built Environment Department of Civil Engineering Building Structures: The Art of Creating Safe and Functional Spaces Remember, building structures is a multifaceted challenge that requires creativity, technical expertise, and attention to detail. As civil engineers, you will shape the built environment, impacting people's lives and communities. Embrace this responsibility, and let's build a better future! Faculty of Engineering and the Built Environment Department of Civil Engineering Reinforced Concrete Reinforced concrete is concrete in which metal (e.g. steel) is embedded so that the two materials act together in resisting forces. Reinforced concrete is a composite material in which concrete's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength or ductility. Reinforcement must: Have high tensile strength. Be easily bent in shape. Surface capable of adequate bond. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) Reinforced Concrete Column Rebars being laid out Faculty of Engineering and the Built Environment Department of Civil Engineering Common Types of Reinforcement for Concrete Rebar (Deformed Bars): Most common type, made from steel with ridges for better bonding. It’s referred to as High Yield bars “Y - bars.” Mild Steel Bars: Smoother than rebar, used for smaller projects, like residential construction. It’s referred to as “R - bars.” Prestressed Concrete: High-strength steel wires or strands, pre-tensioned before concrete is cast. Post-Tensioned Concrete: High-strength steel cables, tensioned after concrete is cast. Fiber-Reinforced Polymer (FRP): Composite materials, resistant to corrosion and chemical damage. Faculty of Engineering and the Built Environment Department of Civil Engineering Common Types of Reinforcement for Concrete Glass Fiber-Reinforced Polymer (GFRP): Lightweight, corrosion-resistant, and suitable for rehabilitation projects. Steel Fibers: Short, thin steel fibers, added to concrete mix for improved tensile strength. Synthetic Fibers: Polypropylene or nylon fibers, used for crack control and impact resistance. Welded Wire Fabric (WWF): Mesh of steel wires, welded together for slab reinforcement. Expanded Metal: Steel mesh, expanded for better bonding and concrete flow. Faculty of Engineering and the Built Environment Department of Civil Engineering Common Types of Reinforcement for Concrete Each type of reinforcement has its own advantages, disadvantages, and applications. The choice depends on factors like structural requirements, environmental conditions, and construction methods. Can be ordered bent in desired shape. Specification example for Beams, Columns, or Slabs: 8Y20-01-250c/c. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Cont’d) Black Rebars Sizes: Diameter: #2 – #11, #14, #18 or 6, 8, 10, 12, 13, 14, 16, 18, 20, 22, 25, 28, 32, 36, 40, 50 mm more details. Concrete Slab Mesh Length: straight: 6 – 15 meters, U-shaped or rounded coils as standards. Faculty of Engineering and the Built Environment Department of Civil Engineering  Rebars are bended according to BS8666-2000 Rebars are bended according to BS4466-1989 Faculty of Engineering and the Built Environment Department of Civil Engineering Rebars are bended according to BS8666:2005 Faculty of Engineering and the Built Environment Department of Civil Engineering Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Beams) Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Columns) Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Forms: The Building Blocks of Engineering (Slabs) Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel Structural steel refers to steel used in construction for building frames, beams, columns, trusses, and other load-bearing elements. It's a crucial material for creating strong, durable, and versatile structures. Here are some key aspects of structural steel: Types: Hot-Rolled Steel: Most common type, formed through a hot-rolling process. Cold-Formed Steel: Shaped through a cold-forming process, often used for lighter structures. High-Strength Steel: Alloyed steel with increased strength and resistance. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel (Cont’d) Shapes: I-Beams (W-Beams): Wide flanges for added stability. H-Beams: Deep beams for heavy loads. Angles: L-shaped for framing and bracing. Channels: C-shaped for added strength. Tubes: Hollow sections for columns and beams. Plate: Flat steel for connections and bases. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel (Cont’d) South Africa Code of practice: SANS 10162 Section types Universal beams (I section) Universal columns (H –section) Roller steel joints Angles Channels T - sections Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel (Cont’d) Applications: Buildings: Frames, beams, columns, and trusses. Bridges: Girders, arches, and suspension systems. Industrial: Equipment, machinery, and storage facilities. Transportation: Infrastructure, like highways and airports. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel (Cont’d) Benefits: Strength: High strength-to-weight ratio. Durability: Resistant to corrosion and fatigue. Versatility: Can be shaped and connected in various ways. Sustainability: Recyclable and reusable. Structural steel is a vital material for modern construction, offering a balance of strength, durability, and versatility. Faculty of Engineering and the Built Environment Department of Civil Engineering Structural Steel (Cont’d) Faculty of Engineering and the Built Environment Department of Civil Engineering Precast Concrete Precast concrete is a construction material made from concrete that is: Prepared: Mixed and cast into a specific shape or form. Cured: Allowed to harden and gain strength in a controlled environment. Transported: Moved to the construction site. Assembled: Put into place to form the final structure. Faculty of Engineering and the Built Environment Department of Civil Engineering Precast Concrete (Cont’d) Precast concrete elements can be: Benefits of precast concrete: 1. Structural: Beams, columns, 1. Quality control: Factory production slabs, and frames. ensures consistent quality. 2. Architectural: Cladding, 2. Speed: Faster construction times due to prefabrication. facades, and decorative 3. Safety: Reduced on-site labour and features. hazards. 3. Infrastructure: Bridge 4. Durability: Long-lasting and components, manholes, and resistant to environmental factors. pipes. 5. Sustainability: Can be made with recycled materials and minimal waste. Faculty of Engineering and the Built Environment Department of Civil Engineering Precast Concrete (Cont’d) Common precast concrete products: 1. Hollow core slabs. 2. Precast walls. 3. Beams and columns. 4. Staircases. 5. Bridge components. 6. Manholes and pipes. 7. Architectural cladding. 8. Prestressed concrete elements. Faculty of Engineering and the Built Environment Department of Civil Engineering Precast Concrete (Cont’d) Faculty of Engineering and the Built Environment Department of Civil Engineering Precast Concrete (Cont’d) Advantages: Disadvantages: 1. Space 1. Inflexible design (not adaptable to discrepancies on site) 2. Reduced cost 2. Large cranes needed 3. Minimized delay 3. Structural connection problems 4. Semi-skilled workers 4. Specialized transportation Faculty of Engineering and the Built Environment Department of Civil Engineering Scaffolds Scaffolds are temporary structures used in construction, maintenance, and repair projects to support workers, materials, and equipment at heights. They provide a safe and stable platform for tasks such as: a) Building construction f) Electrical and plumbing installations b) Painting and decorating g) Maintenance and repair. c) Window installation d) Roofing and gutter work e) Masonry and bricklaying Faculty of Engineering and the Built Environment Department of Civil Engineering Scaffolds (Cont’d) Types of scaffolds: Tube and coupler scaffolds: Made from steel tubes and couplers. System scaffolds: Pre-engineered, modular systems. Suspended scaffolds: Hung from buildings or structures. Supported scaffolds: Resting on ground or floors. Mobile scaffolds: Mounted on wheels or casters. Aerial lifts: Boom lifts, scissor lifts, and forklifts. Faculty of Engineering and the Built Environment Department of Civil Engineering Scaffolds (Cont’d) Components of scaffolds: 1. Standard – The vertical support of a scaffolding. Usually embedded through the ground, though some use barrels and baseplates to support it. 2. Diagonal Braces and Horizontal Braces – The diagonal and horizontal support bars connected to upright standards. 3. Putlogs / Transoms – Horizontal member that connects the wall to a standard. Faculty of Engineering and the Built Environment Department of Civil Engineering Scaffolds (Cont’d) Basic scaffolding diagram. Faculty of Engineering and the Built Environment Department of Civil Engineering Scaffolds (Cont’d) 4. Toeboards – Bottom protective measures to prevent workers from slipping under. 5. Top rails/Guard Rails and Mid Rails – Upper protective measures used to keep workers’ balance in check. 6. Platform – The surface that workers walk on. Scaffolding safety is crucial, and proper installation, inspection, and maintenance are essential to prevent accidents and ensure worker safety. Faculty of Engineering and the Built Environment Department of Civil Engineering A. Double Scaffolding. B. Single Scaffolding. C. Simple Trestle Scaffolding Faculty of Engineering and the Built Environment Department of Civil Engineering A. Cantilever Scaffolding. B. Hanging Scaffolding. C. Steel Frame Scaffolding Faculty of Engineering and the Built Environment Department of Civil Engineering Formworks Formworks are temporary structures used in construction to shape and support freshly poured concrete until it hardens and gains sufficient strength. They: a) Shape the concrete to desired forms and dimensions. b) Support the weight of the concrete and any loads. c) Allow for smooth finishes and accurate tolerances. Common types of formworks: 1. Timber formworks: Traditional, cost-effective, and suitable for complex shapes. 2. Steel formworks: Strong, durable, and reusable. 3. Aluminum formworks: Lightweight, corrosion-resistant, and ideal for large projects. Faculty of Engineering and the Built Environment Department of Civil Engineering Formworks (Cont’d) 4. Plastic formworks: Inexpensive, lightweight, and suitable for simple shapes. 5. Insulated concrete formworks (ICFs): Stay-in-place forms for energy- efficient buildings. 6. Modular formworks: Pre-engineered, modular systems for efficiency and speed. Formworks are used for: a) Foundations. d) Beams g) Architectural Features b) Walls. e) Slabs c) Columns f) Staircases Faculty of Engineering and the Built Environment Department of Civil Engineering Formworks (Cont’d) Proper design, installation, and removal of formworks are crucial to ensure: 1. Structural integrity 2. Surface quality 3. Safety 4. Efficient construction Faculty of Engineering and the Built Environment Department of Civil Engineering Formworks (Cont’d) Basic scaffolding diagram Faculty of Engineering and the Built Environment Department of Civil Engineering Placing and Compaction of Concrete Placing and compaction are critical steps in the concrete construction process. They ensure that the concrete is properly positioned, consolidated, and finished to achieve the desired strength, durability, and appearance. Placing Concrete: 1. Preparation: Ensure the formwork is clean, dry, and well-lubricated. 2. Delivery: Transport concrete to the site in a timely manner. 3. Depositing: Place concrete into the formwork, avoiding segregation and splashing. 4. Spreading: Distribute concrete evenly, using tools like shovels, rakes, or pumps. Faculty of Engineering and the Built Environment Department of Civil Engineering Placing and Compaction of Concrete (Cont’d) Compaction of Concrete: 1. Purpose: Remove air voids, increase density, and improve surface finish. 2. Methods: - Hand tamping: Using hand tools, like tamping rods or tamper plates. - Mechanical vibration: Using vibrating screeds, plates, or poker vibrators. - Internal vibration: Inserting vibrating probes into the concrete. 3. Timing: Compact immediately after placing, before initial set. 4. Duration: Vibrate for 5-30 seconds, depending on the method and mix. Faculty of Engineering and the Built Environment Department of Civil Engineering Placing and Compaction of Concrete (Cont’d) Best Practices: 1. Avoid over-vibration, which can lead to segregation and air entrainment. 2. Use the right tools for the job, considering the mix design and placement method. 3. Monitor temperature and adjust the placement and compaction process accordingly. 4. Ensure proper finishing techniques, like floating and troweling, to achieve the desired surface finish. By following these guidelines, you can ensure that your concrete is properly placed and compacted, resulting in a strong, durable, and visually appealing final product. Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork Brickwork is the construction process of building structures using bricks, which are small, rectangular blocks made of clay, concrete, or other materials. Brickwork involves laying bricks in a specific pattern, using mortar to hold them together, and finishing the surface to achieve the desired appearance. Types of Brickwork: 1. Solid brickwork: Bricks are laid in a continuous pattern, without gaps. 2. Cavity brickwork: Two layers of bricks, separated by a gap, for insulation and weatherproofing. 3. Veneer brickwork: A single layer of bricks, attached to a backing material. Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork (Cont’d) Brickwork Techniques: 1. Stretcher bond: Bricks are laid lengthwise, overlapping each course. 2. Header bond: Bricks are laid widthwise, overlapping each course. 3. English bond: Alternating courses of stretchers and headers. 4. Flemish bond: Alternating stretchers and headers, with headers centered. Brickwork Tools: 1. Trowel: For applying mortar. 2. Level: For ensuring straight courses. Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork (Cont’d) Brickwork Tools: 3. String line: For guiding brick placement. 4. Jointer: For finishing mortar joints. Brickwork Benefits: 1. Durability: Bricks are long-lasting and resistant to weathering. 2. Fire resistance: Bricks are non-combustible and provide fire protection. 3. Thermal mass: Bricks absorb and release heat, regulating building temperatures. 4. Aesthetics: Brickwork offers a unique, attractive appearance. Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork (Cont’d) Common Brickwork Applications: 1. Building exteriors 2. Walls 3. Partitions 4. Fireplaces 5. Patios 6. Walkways By understanding the basics of brickwork, you can appreciate the craftsmanship and durability of this timeless construction method. Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork (Cont’d) Brickwork Bonding Flemish bond Faculty of Engineering and the Built Environment Department of Civil Engineering Brickwork (Cont’d) English bond Stretcher bond Faculty of Engineering and the Built Environment Department of Civil Engineering