Limitations Of Precast Cantilever Construction Method-
In cantilever method construction procedure is very complex.
It require great care to maintain stability of structure during construction.
Special attention is required for precast segments as they have joints. An epoxy agent is used to the joint before putting it in the superstructure.
Size and weight of precast elements are limited by capacity of placing and transportation.
Success of this process relies strongly on accurate geometry control.
Large heavy equipments are needed for erecting the segments.
Pre-casting yard needs investment in equipments.
Segments are fabricated in factories and are taken to the site with the help of transportation ,it may be costly if large distance from construction site.
Components Of an Open Spandrel Arch Bridge
Abutments
Foundation
Road deck
Floor Beam
Spandrel Columns
Arch Ribs or Barrel
Springing lines
Extrados and Intrados
Crown and Rise
Arch axis
Sidewalk
Concrete Requirements
As my structure is an open spandrel Arch bridge that is made up of Reinforced concrete i.e. concrete as well as steel reinforcement hence it can be benefited by using unconventional concrete that is High Strength or High Performance concrete (HSC or HPC). HSC is that concrete which satisfies all the requisites in terms of all the critical fabrication and utilization at the lowest possible cost.It is a new type of concrete that needed unconventional techniques and componenets.It offers high strength as well as durability to the structure.
Now a days HPC is expensive than conventional concrete. It require additional materials in some quantities as to meet specified performance.These additional materials are cement,silica fume,...
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...xibility to engineers and architects. It is often used in prestressed and precast girders which allows logger spans in bridge designs.
Disadvantages:-
Mixture is more prone to early drying problems and Shrinkage cracking.
It require additional admixtures and materials that may be a difficult task to implement them.
High Volume Fly Ash Mixtures
Advantages
Eliminate the problem of balling that was in silica fume
Improve structural strength, reduces bleeding, less cost, more resistant to chemical and sulfate attacks, and it is environmental friendly.
Gives superior finish to structure
Disadvantages
Should be handled properly otherwise may be dangerous
Require better quality control, good knowledge of mix proportions and mixing and good curing at least for 7 days.
Comparing above these two methods for HSC we should use high volume fly ash mixtures for the bridge design.
For almost as long as civilizations began they have been fighting against each other. Often times these wars come down to who has the better military equipment. When one army creates an elite war machine another army is sure to soon copy or improve it. For example the U.S. Army Signal Corps purchased the first ever military aircraft in 1902 (Taylor). Two years later the Italians were also using aircrafts. The trebuchet catapult is no exception; it was one of the most destructive military machines of its time (Chevedden, 2000). A trebuchet works by using the energy of a falling counterweight to launch a projectile (Trebuchet). In this research paper I intend to explain the history and dynamics of a trebuchet catapult.
According to Suspension bridges: Concepts and various innovative techniques of structural evaluation, “During the past 200 years, suspension bridges have been at the forefront in all aspects of structural engineering” (“Suspension”). This statement shows that suspension bridges have been used for over 200 years, and that people are still using them today because they are structurally better bridges. This paper shows four arguments on the advantages of suspension bridges, and why you should use one when building a bridge. When deciding on building a suspension bridge, it has many advantages such as; its lightness, ability to span over a long distance, easy construction, cost effective, easy to maintain, less risk
Current modifications to the design are making them have antiseptic and antimicrobial coatings. Some have a third channel to infuse saline. There have also been efforts to make the surface as smooth as possible to reduce bacterial infections.
The preferred alternative of ODOT is to widen and improve the structural integrity of the Yaquina Bay Bridge. The widening of the bridge shall follow the AASHTO LRFD Bridge Design Specification (Baker, 2008, p.3) using steel pier cap extensions (Quesnell Bridge Widening). The structural integrity of the bridge is to be enhance by improving the fatigue life of welds (Bennett, Matamoros, Barett-Gonzalez, & Rolfe, 2014, p.8)
Based on the above data and the requirements that are to be achieved for the construction of the dam are analyzed. Self compacting concrete has been used mostly in the design of major parts of the dam.For the first time China used new type of admixture known as Glenium type PCE admixture (PCE-3) for the mix used in constructing the power house.The SCC mixture contains large content of limestone powder to increase fluidity,cohesiveness and limit heat generation.These materials are less reactive and reduces the problem of fluidity loss of concrete.Three types of mixes have been used they are....
Throughout the construction industry, technology plays a role to help ease the completion of a project to all of the parties involved. The amount of technology application in the industry supports the belief that technology has a positive impact on project productivity. One of the main materials used in the construction industry that surrounds us every day, in which we overlook, is concrete. Concrete is an art form, in which it takes time and talent in order for it to be used efficiently, to produce its high strength and longevity. However, the downfall of this material is that it is extremely costly and nearly impossible to form it to an aesthetically pleasing surface. In spite of this, what if I told you that there is hope? That the dream of a material made of concrete, producing the same qualities, can be formed to any shape, and used anywhere was a reality.
ement occupies approximately 50% of the mixed concrete volume and is responsible for physiomechanical properties of concrete. Cement production is essential to infrastructure and building construction, creating demands in very large quantities. Energy resources invested in the production process and resulting greenhouse gas emissions have become problematic. The cement production process has become among the world’s largest anthropogenic sources of carbon dioxide emissions, contributing to approximately 5% of global anthropogenic CO2 emissions, (WBCSD, 2009). Increased pressure is being placed on the industry to reduce CO2 emissions, owning to awareness regarding sustainability....
Building Construction procedures involve the erection of various types of structures. The major trend in present-day construction continues away from handcrafting at the building site and toward on-site assembly of even larger, more integrated subassemblies manufactured away from the site. Construction in the United States is the product of a diverse group of subindistries, with many individuals and organizations involved in the construction of a single structure, from the manufacture of necessary components to final assembly. The major elements of a building are as follows: (1) the foundation, which supports the building and provides stability; (2) the structure, which supports all the imposed loads and transmits them to the foundation; (3) the exterior walls, which may or may not be part of the primary supporting structure; (4) the interior partitions, which also may or may not be part of the primary structure; (5) the environmental- control systems, including the heating, ventilating, air-conditioning, lighting, and acoustical systems; (6) the vertical transportation systems, including elevators, escalators, and stairways; (7) communications, which may include such subsystems as intercommunications, public address , and closed-circuit television, as well as the more usual telephone wiring systems; and (8) the power, water supply, and waste disposal systems.
The three most basic types of bridge structures are girder bridges, arch bridges, and suspension bridges (“Bridge Technology,” 2007). The girder structure consists of a chain of beams that are interconnected and supported vertically through the use of well allocated piers. The arch structure utilizes curved elements to disperse the applied forces downwards into end abutments. Finally, the suspension structure exploits the superior tensile strength of steel cables in order to help carry the massive loads applied to the bridge. While some bridges are built basic in structure, others are made through a combination of the structural forms mentioned above (“Bridges,” 2008).
In this report, we will introduce and illustrate on precast concrete, pre-stressed concrete, ready-mix concrete, reinforced concrete, terrazzo and Urbanite in details.
Most people may not realise but concrete plays a vital part in our lives daily. It shapes and creates the built environment in which we are surrounded by, such as schools, bridges, roads, housing, hospitals, dams and so much mores. Concrete is the most used man made material in the world, averaging around 3 tonnes annually for each person. In comparison with other building materials such as wood, steel, plastic and aluminium, over twice as much concrete is used globally than any of these materials. It is the material choice of most purposes due to its strength, durability, thermal mass and its cost.
Constituent materials are the fundamental materials required to produce concrete. The constituent materials of concrete consist of mainly three materials which are cement, aggregate and water, with admixtures included as addictive to alter the characteristics of the concrete (Scalenghe et al., 2011). “Cement is the chemically active constituent but its reactivity is only brought into effect on mixing with water” (Dhir & Yap, 1984). According to Bye (1999), in the industry, Portland cement, which was developed in 1824 by using calcium carbonate found in calcareous rocks, namely limestone or chalk and silica, alumina, and iron oxide found in sedimentary rock, namely clay or shale. Bye (1999) said that cement is produced by grinding the quarried limestone to powder form, blending it with water and heat with pulverized coal to drive out water at 100°C, carbon dioxide at 800°C and clinker at 1400°C, which is then cooled, grounded and mixed with 1%-5% gypsum to alter it fineness and goes through final grinding and the cement is ready to be distributed to the market. According to Sismondo & Sergio (2009), aggregate, which builds up the majority of the volume stability and the durability of the resulting concrete and is of lower price than cement, is always used to the maximum extend as possible in the production of concrete for maximum profit. Aggregates ar...
It produces total quality work the concrete formed with such formwork systems is more durable.
The materials used for the construction of the designed plan is steel of grade415 and to that for coloums and beams is concrete where grade of concrete for coloums is M40 and for beams is M30.
Shah, S., Wang, K. (2004). Development of "green" cement for sustainable concrete using cement kiln dust and fly ash.