Learning Objectives List the main subsectors of the structural sector of infrastructure. 1. Explain the purpose of and list some design considerations for the various components of the structural sector. 2. Identify various components of the structural sector such as building, bridges, dams, leeves, pipes and drains, retaining walls, tunnels, etc. 3. Do Problem 3.1 in textbook (10 points) 1. Do Problem 3.3 in textbook (5 points) 2. Do Problem 3.6 in textbook (5 points) 3. Do Problem 3.7 in textbook (10 points) 4. Do Problem 3.11 in textbook (as class) (20 points) 5. Homework Assignment 3 - Individual Learning Objective - Ch 3 Saturday, January 12, 2019 1:48 PM Ch. 3 Structural Infrastructure Page 1
Transcript
Learning Objectives
List the main subsectors of the structural sector of infrastructure.1.Explain the purpose of and list some design considerations for the various components of the structural sector.
2.
Identify various components of the structural sector such as building, bridges, dams, leeves, pipes and drains, retaining walls, tunnels, etc.
3.
Do Problem 3.1 in textbook (10 points)1.Do Problem 3.3 in textbook (5 points)2.Do Problem 3.6 in textbook (5 points)3.Do Problem 3.7 in textbook (10 points)4.Do Problem 3.11 in textbook (as class) (20 points)5.
Homework Assignment 3 - Individual
Learning Objective - Ch 3Saturday, January 12, 2019 1:48 PM
Ch. 3 Structural Infrastructure Page 1
Subsectors
Foundations•Buildings•Schools•Bridges•Dams•Levees and Floodwalls•Retaining Walls•
Structural SectorSaturday, January 12, 2019 1:48 PM
Ch. 3 Structural Infrastructure Page 2
Virtually any structure, be it a building or a bridge, requires a foundation. The foundation may be as simple as a concrete slab, or much more complicated. Foundations are necessary to distribute the weight of the structure onto the soil or rock below it. Without a proper foundation, a structure may sink (settle), tip, crack, or collapse. The strength of the soil or rock below a structure is a critical factor in foundation design. ‘‘Weak’’ soil or rock cannot support much weight. Consequently, the structure’s weight must be distributed over a larger area in contact with the soil or rock; this is the fundamental principle behind footings
Penn, Michael R.. Introduction to Infrastructure (Page 42). Wiley Higher Ed. Kindle Edition.
Foundations must be designed to support the dead load and live load of buildings and other structures. Dead load is the gravitational weight of the structure itself. Live loads are imposed on the structure by gravity, wind, earthquakes, and the building contents.
1.
Foundations are generally classified into two general categories: 1) Shallow foundations, and 2) deep foundations.
2.
The strength and potential compressibility of the soil play a prominent role in the design of the foundation system. Geotechnical engineers work with structural engineers to design foundations.
3.
Generally, the foundation must be checked for: 1) bearing capacity, 2) settlement, and 3) deflections.
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Design Considerations
Foundations - Introduction and Design ConsiderationsSaturday, January 12, 2019 1:48 PM
Ch. 3 Structural Infrastructure Page 3
Spread footingfoundation
Shallow FoundationsSaturday, January 12, 2019 1:48 PM
Ch. 3 Structural Infrastructure Page 4
Different Types of DeepFoundations
Pile Driven into Ground
Pile and Mat Foundation
Deep FoundationsSaturday, January 12, 2019 1:48 PM
Ch. 3 Structural Infrastructure Page 5
Three Story Building Collapses , Bearing Capacity Failure Maihar Madhya Pradesh.K Bamel
Bearing Capacity FailureSaturday, January 12, 2019 1:48 PM
High-rise structures, while typically privately owned, are of particular importance to infrastructure systems due to the demands created by a large number of people occupying a relatively small footprint; a high-rise condominium may ‘‘concentrate’’ the population equivalent of a small city into the area of a single city block. Needs for water, wastewater, parking, and traffic must be carefully considered when designing these structures and their integration into existing infrastructure systems. The structural design of skyscrapers and the design of the foundations are extremely complex, requiring education beyond a bachelor’s degree.
Penn, Michael R.. Introduction to Infrastructure (Page 43). Wiley Higher Ed. Kindle Edition.
Design Considerations
Limit State Design1.Speed of Building Construction2.Loadings3.Strength and Stability4.Drift Limitations5.Stiffness6.Human Comfort7.Creep, Shrinkage and Temperature Effects8.Fire9.Foundation Settlement and Soil-Structure Interaction10.https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
Buildings - Introduction and Design ConsiderationsSaturday, January 12, 2019 1:48 PM
The aim of this approach is to ensure that all structures and their constituent components are designed to resist with reasonable safety the worst loads and deformations that are liable to occur during construction and service, and to have adequate durability during their lifetime. The entire structure, or any part of it, is considered as having “failed” when it reaches any one of various “limit states.
“Two types of limit states must be considered: The ultimate limit states, corresponding to the loads to cause failure, endangering lives and causing serious financial losses, the probability of failure must be low. The serviceability limit states, which involve the criteria governing the service life of the building. Since the consequences are not catastrophic, a much higher probability of occurrence is permitted. A particular limit state may be reached as a result of an adverse combination of random conditions.
Partial safety factors are employed for different conditions that reflect the probability of certain occurrences or circumstances of the structure and loading existing. The implicit objective of the design calculations is then to ensure that the probability of any particular limit state being reached is maintained below an acceptable value for the type of structure concernedhttps://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
Buildings - Limit State Design PhilosophySaturday, January 12, 2019 1:48 PM
The speed of elections a vital factor in obtaining a return on the investment by minimizing the cost of interest payments on the large capital costs involved in such large-scale projects. Most tall buildings are constructed in congested city sites with difficult access, and with no storage areas. Careful planning and organization of the construction sequence become essential. The story-to-story uniformity of most multi-story buildings encourages construction through repetitive operations and prefabrication techniques. The progress in the ability to build tall buildings has gone hand in hand with the development of more efficient equipment and improved methods of construction, such as:-Slip-and flying-formwork-Concrete pumping-The use of climbing tower cranes and large mobile cranes. https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
The dead load includes loads that are relatively constant over time, including the weight of the structure itself, and immovable fixtures such as walls, plasterboard or carpet. The roof is also a dead load. Dead loads are also known as permanent or static loads. Building materials are not dead loads until constructed in permanent position.[8][9][10] IS875(part 1)-1987 give unit weight of building materials, parts, components.Live load, imposed loads, transient load[edit]Live loads, or imposed loads, are temporary, of short duration, or a moving load. These dynamic loads may involve considerations such as impact, momentum, vibration, slosh dynamics of fluids and material fatigue.Live loads, sometimes also referred to as probabilistic loads, include all the forces that are variable within the object's normal operation cycle not including construction or environmental loads.Roof and floor live loads are produced during maintenance by workers, equipment and materials, and during the life of the structure by movable objects, such as planters and people.Bridge live loads are produced by vehicles traveling over the deck of the bridge.Environmental loads[edit]Environmental Loads are structural loads caused by natural forces such as wind, rain, snow, earthquake or extreme temperatures.Wind loads•Snow, rain and ice loads•Seismic loads•Hydrostatic loads•Temperature changes leading to thermal expansion cause thermal loads•Ponding loads•Frost heaving•Lateral pressure of soil, groundwater or bulk materials•Loads from fluids or floods•Permafrost melting•Dust loads•
From <https://en.wikipedia.org/wiki/Structural_load>
Buildings - LoadingsSaturday, January 12, 2019 1:48 PM
The primary requirement of the ultimate limit state design procedure is that the structure have adequate strength to resist and remain stable under the worst probable loads during its lifetime. This includes all critical load combinations, augmented moments from second-order deflections (P-delta) plus an adequate reserve, study all critical members whose failure may lead to a progressive collapse of part or the whole structure. Finally, the whole building must be checked against toppling as a rigid body about one edge of the base. Moments are taken about that edge with the resisting moment of the dead weight of the structure to be greater than the overturning moment by an acceptable factor of safety (FS > 3).https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
Toppling or overturning failure
The collapse at the Lotus Riverside, a complex of 11 residential buildings in Shanghai, early on Saturday morning killed one construction worker and left hundreds of prospective tenants angrily demanding their money back.
From <https://www.telegraph.co.uk/news/worldnews/asia/china/5685963/Nine-held-over-Shanghai-building-collapse.html>
Buildings - Strength and StabilitySaturday, January 12, 2019 1:48 PM
First, the definitions: Lateral (story) drift is the amount of sidesway between two adjacent stories of a building caused by lateral (wind and seismic) loads (Fig. 11.1). For a single-story building, lateral drift equals the amount of horizontal roof displacement. Horizontal deflection of a wall refers to its horizontal movement between supports under wind or earthquake loading. Vertical deflection of a floor or roof structural member is the amount of sag under gravity or other vertical loading.
FIGURE 11.1: Story drift caused by lateral loads.From <https://www.globalspec.com/reference/70269/203279/chapter-11-lateral-drift-and-vertical-deflections>
The parameter that measures the lateral stiffness is the drift index. It is defined as the ratio of the maximum deflection at the top of the building to the total height of the building. In addition, each floor has an index called the inter-story drift index which checks for localized excessive deformation. There is no national code requirement for the drift index, but 1/400 is a traditionally accepted limit. Different countries use from 0.001 to 0.005 (1/1,000 to as low as 1/200). Lower values are used for hotels and condominiums because the noise and discomfort at those levels are unacceptable. For conventional structures, the preferred range is 0.0015 to 0.0030 (in other words, from 1/700 to 1/350).https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
Buildings - Drift LimitationsSaturday, January 12, 2019 1:48 PM
Stiffness: The lateral stiffness is a major consideration in the design of a tall building. Under the ultimate limit state, the lateral deflections must be limited to prevent 2nd-order P-delta effects from gravity loading to be large enough to precipitate collapse. In addition, serviceability requires these deflections not to affect elevator rails, doors, glass partitions, and prevent dynamic motions to cause discomfort to the occupants and sensitive equipment. This is one of the major differences of tall buildings with respect to low-rise buildings.https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
Buildings - Lateral StiffnessSaturday, January 12, 2019 1:48 PM
Buildings subjected to both lateral and torsional deflections (plus vortex shedding and other usual effects) may induce in their human occupants from discomfort to acute nausea. These are major factors in the final design of the building. When a tall structure is subjected to lateral loads, the resulting oscillatory movements can induce a wide range of responses in the building’s occupants, ranging from mild discomfort to acute nausea. This may prove the structure undesirable or un-rentable. There are no codified standards for comfort criteria. A dynamic analysis is required to determine the response of the structure in order to determine its adequacy to the comfort criteria.https://www.slideshare.net/ce_arafat/basic-design-criteria-for-high-rise-buildings-62473145
How Tall Buildings Tame the Wind | The B1MThe B1M
Buildings - Human ComfortSaturday, January 12, 2019 1:48 PM
