Design of the Office Building of Yangzhou Yangtze River Group文献综述

文献综述

I) Briefly talk about the cognition and experience of concrete structure.Concrete is perhaps the most widely used building material in the world today, thanks to its availability and versatility. Its also the material we have to thank for some of the worlds most impressive buildings, including the Sydney Opera house, the Lotus Temple in Delhi, and the Burj Khalifa in Dubai.Concrete is one of the most frequently used building materials worldwide. The distinctive characteristics like strength, durability, low-maintenance, energy-efficient, sustainability are the reasons for wide range usage of concrete in the field of civil engineering. You can find concrete almost anywhere you look, including buildings, bridges, walls, swimming pools, roadways, airport runways, floors, patios or even a cement house. All of these structures depend on a man-made material with a simple formula. How is all that concrete made?Concrete is composed of cement, water and coarse aggregates. When mixed together, they create a construction material that hardens over time. How much water and cement you use determine the properties of concrete, such as: Strength Durability Resistance to heat or radiation WorkabilityFresh concrete has many applications and can be cast into circles, rectangles, squares and more. It can also be used for staircases, columns, doors, beams, lentils and other familiar structures. Concrete is made in different grades, including normal, standard and high-strength grades. These grades indicate how strong the concrete is and how it will be used in construction. What kind do you need? Our guide can help you decide based on your project requirements.How Do You Make Concrete?When you make concrete, regardless of what you plan to use it for, you have to mix the right proportions to achieve the quality you desire. You can use different mixes to make concrete:1. Nominal mix2. Design mix3. Machine mixing4. Hand mixingUses of ConcreteThe major uses of concrete are1. Concrete Dams2. Residential Buildings3. Commercial Buildings4. Roads or Driveways5. Marine Construction6. Culverts and Sewers7. Foundations8. Fences9. Concrete BridgesOther Uses As the concrete is an important part of a building, it is prioritized over wood as a construction material. Concrete once cast and cured does not require any maintenance and can hold up against any weather condition. Concrete is a non-combustible or decaying material that makes it inert material that doesnt burn, mildew or feed rot. Its superior structural integrity provides an added degree of protection from the severe weather as well as an earthquake. Concrete is produced from locally available materials and leaves a small environmental footprint while still providing high-level durability. Concrete can be shaped in various forms when freshly mixed. A concrete floor can be stamped to create an attractive surface. It can admit natural light during the day and transmit artificial light after work. It is a durable and cost-effective material which is a necessity for underground use.Main Properties of Concrete for ConstructionConcrete is a mixture of several materials. At the hardened state, this heterogeneous material becomes stone-like mass. The extensive use of concrete in the construction field has made it a material of huge concern for engineers. To participate in the vast uses of concrete an engineer must know its properties.Strength, Workability, Elastic Properties, Durability, Impermeability, Segregation, Bleeding, FatigueHow Concrete Buildings Are Made?Concrete buildings are made with metal forms, which hold the concrete in place while it cures. Typically, the forms are set into place and then braced. Rebar, grooved steel rods of various thicknesses, are placed inside the forms to reinforce the concrete.The first step in the making of a concrete building is its design. Designers take into consideration how the characteristics of concrete, including its weight, strength and stability, will affect their design. This is important because the concrete walls and floors become the structure of the building.DesignThe first step in the making of a concrete building is its design. Designers take into consideration how the characteristics of concrete, including its weight, strength and stability, will affect their design. This is important because the concrete walls and floors become the structure of the building. In a skyscraper, the concrete must be able to withstand the weight of many floors.FormsConcrete buildings are made with metal forms, which hold the concrete in place while it cures. Typically, the forms are set into place and then braced. Rebar, grooved steel rods of various thicknesses, are placed inside the forms to reinforce the concrete. Some buildings are constructed of poured concrete pillars and floors, with other materials used to construct the walls.PouringConcrete is poured into the forms by large trucks. Some have booms that pump the concrete up from the truck container and deposit it into the forms. The foundation and the floor of the concrete building are poured first. Utility pipes are pre-installed before the concrete is poured. Once the floor and foundation have cured, the walls and pillars can be poured. Rebar from the floor is tied to the rebar set in the wall forms. Concrete buildings can be constructed level by level in this fashion.The Advantages of ConcreteYou dont become the second most used material on Earth for no reason. What are the key advantages of using concrete for building structures?Concrete is Easily AvailableAs stated above, concrete is made up of four incredibly simple components; cement, aggregates, sand and water. Since each of these key ingredients is readily available from a variety of sources, not only are they easy to acquire, theyre also affordable.Both the ease of getting the ingredients and how simple it is to make are key reasons why concrete is a popular choice when it comes to large structures like overpasses.Concrete is Easy to ShapeWhen concrete is in its green (wet) state, its incredibly easy to shape and mould, which means its a great choice for a variety of functions. While its in its wet state, concrete is also easy to transport from the place it was mixed to the place where it will be used and left to set.Concrete is Extremely VersatileAnother great advantage of concrete is that it can be manufactured specifically to a desired strength, depending on the structures requirements. For example, concrete is often reinforced with steel in order to create a material with a high compressive strength compared to others. Reinforced concrete also requires little to no maintenance and lasts a long time.From single blocks to entire flyovers, concrete structures are incredibly robust and durable, which is one reason its so widely used.Concrete is Non-CombustibleUsing concrete for structures adds extra fire safety since concrete is non-combustible by nature. Its ranked as a class A1 building material, which means it has the highest classification of fire resistance.Concrete can also withstand extremely high temperatures and does not exude any toxic fumes when affected by fire.Concrete is DurableNot only does concrete stand up to the test of time and fire, but it is also resistant to wind and water. This is why concrete is a popular material for building storm shelters or weatherproofing other structures such as barns.Disadvantages of ConcreteNow that weve looked at why concrete is the worlds favourite building material, were going to explore some of the disadvantages of concrete structures.Low Tensile StrengthWhen compared to other building materials, concrete is shown to have rather low tensile strength, which can lead to the concrete cracking under too much tension. Therefore larger concrete structures require the concrete to be reinforced with steel.Cracks in concrete can also be caused by drying, shrinkage and moisture expansion. This is another reason why most concrete needs to be reinforced.Concrete is Not SustainableUnfortunately, concrete is not the most environmentally sustainable choice when it comes to building materials. It has been claimed that because of its worldwide popularity, concrete is responsible for 5% of the worlds total carbon emissions.If youd like to learn about more sustainable alternatives to concrete, why not read our blog below?Concrete is Susceptible to EfflorescenceConcrete can sometimes contain soluble salts, which, when the water in the concrete evaporates, causes efflorescence.Efflorescence in concrete shows as a whitish coloured salt deposition that sits on the surface of the concrete when the moisture evaporates. However, efflorescence can be removed from the concretes surface simply by using a dilute solution of household white vinegar and water.While concrete isnt without its flaws, it still remains the most used building material across the globe and will probably stay that way for a little while more.2) General steps of structural concrete design.The primary objective of structural analysis and design is to produce a structure capable of resisting all applied loads without failure during its intended life. If improperly designed, elements of a structure would fail causing serious consequences such as large expenses or ultimately losses in lives which cannot be compared with any cost.Once the architectural engineer sets the function and layout of the structure, the role of the structural engineer begins which can be summarized in the following steps to develop a safe, functional and economic structures.STEP 1: CONCEPTUAL DESIGN In this stage, initial design of the building elements (e.g. slabs, beams, columns etc.) is performed based on code recommendations.It starts with selecting the appropriate columns locations and orientation in such a way that they do not interfere with the architectural drawings. For example, you do not want a column to be in the middle of a room or something like that. Also, one should consider that at least 30% of the total number of columns to be in either x- or y- directions to give adequate earthquake resistance of the building.After that, the type of structural system is selected. For instance, the slab might be chosen to be solid slab, hollow block or flat slab etc. Accordingly, the location of beams are determined.STEP 2: DETERMINING THE INTERNAL FORCES OF EACH ELEMENTAfter finishing the initial design, the exact dimensions of each building element shall be determined. First, an analysis model is created for the building with its initial dimensions as determined from STEP 1 on an analysis software such as SAP 2000.All the loads that act on the structure have to defined in the model such as dead loads, live loads, wind and earthquake loads etc.From the model, the internal forces [Normal Force, Shear Force, Bending Moments] on each elements is calculated.STEP 3: ITERATIVE DESIGNNow you have the straining actions on the elements based on the initial sizing and simply, you can use them to design according to the relevant code. The design process became so easy by using some spreadsheets or any other software that facilitates the design.Next, the analysis model should be modified to the new dimensions obtained from the previous design and the analysis is re-run. Internal forces are obtained and design is made again based on the new forces.This iterative process is repeated until the element design be the same in two following iterations.STEP 4: FOUNDATION DESIGNAfter the final dimensions of members are found, the foundation system type can be selected taking in consideration, the bearing capacity of the soil and the loading coming from the structure.STEP 5: DRAFTINGIn this step, the structural plans are created. These plans should be fully detailed such that the construction process in the site can proceed smoothly and not delayed due to missing data in the drawings.What are the basics of structural design?Structural design is the process of creating a safe and functional structure under any load that it may experience. Generally, there are four steps: (1) modelling, (2) load analysis, (3) structural analysis, and (4) design.3) Discuss the contents, problems and solutions of structural concrete design.Concrete is one of the most used building materials in the world. Concrete is a mixture of powdered cement, sand, aggregate such as stone, and water. It allows for treatment and has high compressive strength and low tensile strength. In contrast, reinforced concrete (RC) is a mixture of concrete with reinforcements (steel bar).RC is a building material discovered in late 19th century and was credited for inventing it into Joseph Louis Lampot in 1848 and has obtained a patent through the design of 1867 reinforced garden basins, and then beams-patented concrete beams and elements for railways and road fences. After that, the major developments of the armed concrete began since the year 1900 [3]. RC columns (RCC) are usually structural linear elements, which are generally casted vertically. RC is containing embedded plates, steel bars, or fibers that support the material. Also, RC is responsible for carrying loads from floors to foundations. The stability, inflexibility, and strength of any structure are closely associated with the strength and robustness of the columns. The capacity to carry loads is maximized by these materials, and because of this, RCC is widely used in all construction. In fact, building materials have become the most used. Therefore, the concrete columns must be reinforced identically to the global analysis of the structural system, in order to ensure quality, efficiency and security.RC, as a building material, is used extensively around the world because of its importance in the development of urbanization. It has a lot of pros and cons. For example, some advantages of armed concrete are: 1. Compared to other construction materials, RC has high compressive strength. 2. RC can withstand a great deal of tensile stress due to the reinforcement provided. 3. Fire resistance and weather. 4. Considered to be more robust building system than any other building system for RC. 5. Initially, RC, as liquid materials, can be formed in an almost unlimited range of shapes. 6. Less skilled labour to establish the structure, compared to using steel in the structure.On the other hand, some disadvantages: 1. Tensile strength up to ten compressive strength. 2. RC steps are mixing, casting, and processing, which undoubtedly have a significant impact on the final power. 3. The cost of models used for casting RC is quite higher. 4. Deflation causes crack expansion and loss of strength. There are many topics to be presented such as: concrete materials and different environments that are exposed to concrete and durability, concrete durability in the global building code, distressed RC tradition structures, concrete cracks, corrosion, and causes of deterioration, and solutions for the treatment of these problems, for example concrete injectors, repair by concrete, repair and prevention of rust, especially cathodic protection, reinforcing bars made of fiber reinforced plastic (FRP). Developed countries spend a huge proportion of their annual infrastructure budgets on repairs, maintenance and replacement of present and new structures, which is a significant indication of deficiencies in past construction practices, designs and techniques.

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