Construction and Building Loads

1. Constructionand Building Loads

2. Construction Standards • 2. Construction Technologies • Central Concepts: The construction process is a series of actions taken to build a structure, including preparing a site, setting a foundation, erecting a structure, installing utilities, and finishing a site. Various materials, processes, and systems are used to build structures. Students should demonstrate and apply the concepts of construction technology through building and constructing either full-size models or scale models using various materials commonly used in construction. Students should demonstrate the ability to use the engineering design process to solve a problem or meet a challenge in construction technology. • 2.1 Identify and explain the engineering properties of materials used in structures (e.g., elasticity, plasticity, R value, density, strength). • 2.2 Distinguish among tension, compression, shear, and torsion, and explain how they relate to the selection of materials in structures. • 2.3 Explain Bernoulli’s principle and its effect on structures such as buildings and bridges. • 2.4 Calculate the resultant force(s) for a combination of live loads and dead loads. • 2.5 Identify and demonstrate the safe and proper use of common hand tools, power tools, and measurement devices used in construction. • 2.6 Recognize the purposes of zoning laws and building codes in the design and use of structures.

3. Changing Construction Development • Materials – properties of material change • Early Timber & Masonry ~ limit to 5 stories • Wrought Iron & Steel in mid 1880s ~ I beams etc allowed longer spans such as bridge spans. • Structural Concrete after 1900 ~ rebar – reinforcement bar along with structural steel allows for taller building • The Elevator • Became popular in late 1850’s with of the safety brake by Elisha Otis • Made upper stories attractive to rent • Made tall buildings financially viable • Construction Technology • More efficient equipment – fluid energy (heavy equipment, nail guns) • Improved methods – balloon vs platform use of trusses ( and materials) • Increase Speed

4. Types of Structures

5. Designs DifferencesOffice vs Residential • Office/Commercial buildings • Large entrances and open spaces means long building spans • Reconfigurable space floating partitions (large column, open areas) • Residential buildings • Partitions are frequent and the same from story to story to form load bearing walls • Shorter spans – size of structural members smaller

6. Loading • Buildings are designed to carry all gravity loads and lateral loads to be seen during construction and service. • Must consider sequential loading (particularly during construction) • Types of Loading: • Dead (Weight of structure & fixtures) • Live (Occupancy Loads) • Impact (hammering, marching on a bridge, machines that have vibrations) • Snow • Wind • Temperature (expanding and shrinking) • Seismic

7. Dead Load • Dead loads are the weights of all items permanently attached to the structure. • Dead loads in a residential structure are usually calculated at 20 lbs psf (per square foot). • Partitions (interior walls) are usually 20 lbs psf.

8. Live Loads • Live loads are any loads that are not permanently attached to the structure. • Live loads in a residential structure generally are expected to be 40 lbs psf (per square foot). What do the Two white arrows represent? Forces are equal and opposite so the white arrows indicate an upward force on the bottom of the footing to support the house. What do the three red arrows represent? Wind, Snow, People, Furniture all live loads. What does the blue arrow represent? Attic storage which is also a live load.

9. Tributary Areas • Useful for determining member forces due to UNIFORMLY APPLIED loads (dead, live, pressure, etc....) on SIMPLY SUPPORTED members. • Structural analysis theory to find the “path” that loads take as they “find their way” down to the foundation through the structural members.

10. Tributary Area On A Floor • Applied load is uniformly distributed. Each member supports the load and transfers it to a larger member. Tributary area on the post or lally column.

11. DL Calculation on a floor with a ceiling below. Floor Dead Load 1/4” Linoleum (w/glue) 1.8 psf 1/2” Underlayment (plywood) 2.0 psf 5/8” Plywood (sub floor) 2.2 psf 2x12 @ 16” O.C. (on center) 3.5 psf 5/8” Gypsum Board (Sheetrock) 3.2 psf Metal suspended ceiling 2.1 psf Misc. 1.5 psf Total 16.3 psf

12. DL Roof Calculation

13. Structural Forces • Structural ForcesA force is a push or pull that transfers energy to an object.  Structural materials are subjected to both internal and external forces and must be considered by engineers as they design safe and lasting structures. • Internal ForcesInternal forces are those that act within structural materials.  They are forces exerted by one part of a structure onto another.  The source or cause of internal forces may be either internal or external.  Examples of internal forces are tension, compression, torsion, bending, and shear. • External Forces (Load)A load is an external force on a structure.  It may be caused by physical weight on a structure, or by environmental sources such as wind, water, or temperature.

14. Parts of a Structure • Structural MemberEach individual part of a structure is called a member.  • The attachment point of two or more members is called the joint.  • Horizontal members are called beams, and are built to withstand bending.  • Vertical members are called columns, and must withstand compression.

15. Compression • CompressionA force that pushes or squeezes is called compression.  A structural material in compression may be shortened or crushed.

16. Tension • TensionTension is a force that pulls or stretches. Tensile StrengthThe ability of a material to withstand tension without parting is called tensile strength.

17. Bending • BendingWhen a straight member becomes curved, one side is in tension while the other is in compression.  Engineers must either prevent bending, or select materials that can perform well in both tension and compression.

18. Torsion • Torsion the twisting of a structural member by the exertion of forces to turn one end or part about a longitudinal axis while the other is held fast or turned in the opposite direction

19. Shear • ShearShear is a force that causes parts of a material to slide past one another in opposite directions, usually in a parallel manner.  Shear may also be described as a sliding force.

20. Constructing Buildings (Gehl Co.)

21. Zoning Laws • What do zoning regulations do? • Zoning regulations establish how the land can be used, either for residential, industrial, commercial, or recreational purposes. • Designed to protect you, your neighbors, and the community from undesirable, or inappropriate, land uses and/or construction. • They can protect property value by planning for the future of the town and preventing a business or industry from misuse of the land.

22. Building Codes • Building Codes Regulations established by a local government describing the minimum structural requirements for buildings. Specifications involve the foundation, roofing, plumbing, electrical, and other matters of safety and sanitation.

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24. Constructing Buildings • Preparing the site • choosing a location • Check zoning & Building codes • purchasing the land • clearing • grading • leveling the site. (Gehl Co.)

25. Constructing Buildings • Setting The Foundation • Two Parts of the foundation • - Footing distributes the weight of • the structure on the ground. • - Foundation wall Transfers the weight • of the structure to the footing. • Types of foundations: T-foundation, • Slab & Pier (Gehl Co.)

26. Constructing Buildings • Building the Framework • frame of a house is like a skeleton • - Footing distributes the weight of • the structure on the ground. • - Foundation wall Transfers the weight • of the structure to the footing. • Types of foundations: T-foundation, • Slab & Pier (Gehl Co.)