Construction of Railway Track Methods

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Construction of Railway Track Methods

There are three distinct methods of construction of railway track. These are:

Telescopic Method
Tramline Method
Mechanical Method

1. Telescopic Method of Construction of Railway Track

In this method, rails, sleepers and fastenings are unloaded from the material train as close to the rail head as possible. The sleepers are carried by carts or men along the adjoining service road and spread on the ballast. The rails are then carried on pairs to the end of last pair of connected rails and linked.

To carry rails manually over a long distance is a tedious job. So certain carriers called Anderson rail. Carriers are used to carry rails to the ends of the rail head.

It can also take rails up to a head last pair linked with the help of temporary track consisting of 3″ x 3″ angle irons of the same length as rails and fastened to the sleepers.

A further consignment of the material is deposited at the advances rails head and the procedure is repeated.

2. Tramline Method Railway Track Construction

This method is used where tram carrier are installed for carrying earthwork or in rainy season due to difficulty in movement of cart. Some tramline is established on with a gauge of 2′-2′-6″. The basic difference between this and telescopic method lies in the conveyance and spreading of the sleepers.

The track can be assembled at more than one points simultaneously, which is the great advantage of this method. Sometimes an additional track is laid on the side of existing track for which this method is best.

3. Mechanical Method Railway Track Construction

This method is extensively used in Britain and America by using special track laying machine. There are two types of machines available. In first type of machine, the track material carried by the material. Train is delivered at the rail head and laid in the required position by means of projecting arm or mounted on the truck nearest to the rail head. The material train moves forward on the assembled track and operation is repeated.

In the second type of machines a long cantilevered arm projecting beyond. The wagon on which is fitted. A panel of assembled track consists of pair of rail with appropriate number of sleepers on the ballast layer. This panel is conveyed by special trolley running over the wagons of material train to the jibs. It is lowered by the jib in the required position and connected to the previous panel. The track laying machine then movies forwarded and operation is repeated.

Retaining Wall with Anchors Analysis and Design Spreadsheet

This spreadsheet provides the design and analysis of retaining wall with anchors.
Retaining walls with anchors shall be dimensioned to ensure that the total lateralload, Ptotal, plus any additional horizontal loads, are resisted by the horizontal component of the anchor Factored Design Load Thi, of all the anchors and the reaction, R, at or below the bottom of the wall. The embedded vertical elements shall ensure stability and sufficientpassive resistance against translation. The calculated embedment length shall be the greater of that calculated by the Designer or Geotechnical Services.

Typical design steps for retaining walls with ground anchors are as follows:

Step 1 : Establish project requirements including all geometry, external loading conditions (temporary and/ or permanent, seismic, etc.), performance criteria, and construction constraints. Consult with Geotechnical Services for the requirements.

Step 2 : Evaluate site subsurface conditions and relevant properties of the in situ soil or rock; and any specifications controlled fill materials including all materials strength parameters, ground water levels, etc. This step is to be performed by Geotechnical Services.

Step 3 : Evaluate material engineering properties, establish design load and resistance factors, and select level of corrosion protection. Consult with Geotechnical Services for soil and rock engineering properties and design issues.

Step 4 : Consult with Geotechnical Services to select the lateral earth pressure distribution acting on back of wall for final wall height. Add appropriate water, surcharge, and seismic pressures to evaluate total lateral pressure. Check stability at intermediate steps during contruction. Geotechnical numerical analysis may be required to simulate staged construction. Consult Geotechnical Services for the task, should it be required.

Step 5 : Space the anchors vertically and horizontally based upon wall type and wall height. Calculate individual anchor loads. Revise anchor spacing and geometry if necessary.

Step 6 : Determine required anchor inclination and horizontal angle based on right-of-way limitations, location of appropriate anchoring strata, and location of underground structures.

Step 7 : Resolve each horizontal anchor load into a vertical force component and a force along the anchor.

Step 8 : Structure Design checks the internal stability and Geotechnical Services checks the external stability of anchored system. Revise ground anchor geometry if necessary.

Step 9 : When adjacent structures are sensitive to movements Structure Design and Geotechical Services shall jointly decide the appropriate level and method of analysis required. Revise design if necessary. For the estimate of lateral wall movements and ground surface settlements, geotechnical numerical analysis is most likely required. Consult with Geotechnical Services for the task, should it be required.

Step 10 : Structure Design analyzes lateral capacity of pile section below excavation subgrade.
Geotechnical Services analyzes vertical capacity. Revise pile section if necessary.

Step 11 : Design connection details, concrete facing, lagging, walers, drainage systems, etc.
Consult with Geotechnical Services for the design of additional drainage needs.

Step 12 : Design the wall facing architectural treatment as required by the Architect.

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Excel Construction Management Templates

Excel Construction Management Templates are very important for managers as it’s very difficulit to manage construction projects. they Require alot of stakeholders, details and documentation. So we provide more than 15 free excel construction management templates to download and use themthe templates involve :

Construction Timeline
Construction Budget
Construction Estimator
Bid Tabulation Template
Abstract of Bids Template
Subcontractor Documentation Tracker
Construction Documentation Tracker
Daily/Weekly Inspection Report
Contractor Progress Payment Template
Change Order Request Summary
Change Order Log
Request for Information Log
Residential Remodel Project Timeline
Certified Wage & Hour Payroll Form
Time & Materials Invoice
Project Punchlist
Project Closeout Checklist
Construction Management with Smartsheet

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Design of Bridge Slab Spreadsheet

Reinforced Slab Bridges used For short spans, a solid reinforced concrete slab, generally cast in-situ rather than precast, is the simplest design to about 25m span, such voided slabs are more economical than prestressed slabs.

Slab bridges are defined as structures where the deck slab also serves as the main load-carrying component. The span-to-width ratios are such that these bridges may be designed for simple 1-way bending as opposed to 2-way plate bending. This design guide provides a basic procedural outline for the design of slab bridges using the LRFD Code and also includes a worked example.

The LRFD design process for slab bridges is similar to the LFD design process. Both codes require the main reinforcement to be designed for Strength, Fatigue, Control of Cracking, and Limits of Reinforcement. All reinforcement shall be fully developed at the point of necessity. The minimum slab depth guidelines specified in Table 2.5.2.6.3-1 need not be followed if the reinforcement meets these requirements.

For design, the Approximate Elastic or “Strip” Method for slab bridges found in Article 4.6.2.3 shall be used.
According to Article 9.7.1.4, edges of slabs shall either be strengthened or be supported by an edge beam which is integral with the slab. As depicted in Figure 3.2.11-1 of the Bridge Manual, the #5 d1 bars which extend from the 34 in. F-Shape barrier into the slab qualify as shear reinforcement (strengthening) for the outside edges of slabs.

When a 34 in. or 42 in. F-Shape barrier (with similar d1 bars) is used on a slab bridge, its structural adequacy as an edge beam should typically only need to be verified. The barrier should not be considered structural. Edge beam design is required for bridges with open joints and possibly at stage construction lines. If the out-to-out width of a slab bridge exceeds 45 ft., an open longitudinal joint is required.

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Steel Connection Design Spreadsheet

Steel Connection is divided into two common methods: bolting and welding.
Bolting is the preferred method of Steel connecting members on the site. Staggered bolt layout allows easier access for tightening with a pneumatic wrench when a connection is all bolted. High strength bolts may be snug-tightened or slip-critical. Snug-tightened connections are referred to as bearing connections Bolts in a slip-critical connection act like clamps holding the plies of the material together.Bearing type connections may have threads included ( Type N ) or excluded ( Type X ) from the shear plane(s). Including the threads in the shear plane reduces the strength of the connection by approximately 25%. Loading along the length of the bolt puts the bolt in axial tension. If tension failure occurs, it usually takes place in the threaded section.Three types of high strength bolts A325, A490 (Hexagonal Head Bolts), and F1852 (Button Head Bolt). A325 may be galvanized A490 bolts must not be galvanized F1852 bolts are mechanically galvanized. High strength bolts are most commonly available in 5/8” – 1 ½” diameters. Bolting requires punching or drilling of holes. Holes may be standard size holes, oversize holes, short slotted holes, long slotted holes

Due to high costs of labor, extensive field -welding is the most expensive component in a steel frame. Welding should be performed on bare metal. Shop welding is preferred over field welding. The weld material should have a higher strength than the pieces being connected.Single-pass welds are more economical than multi-pass welds. The most economical size weld that may be horizontally deposited in one pass has 5/16”. Fillet welds and groove welds make up the majority of all structural welds. The strength of a fillet weld is directly proportional to the weld’s throat dimension. The capacity of a weld depends on the weld’s throat dimension and its length.

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Reinforced Concrete Mechanics and Design 5th Edition

Reinforced concrete design encompasses both the art and science of engineering.

This book presents the theory of reinforced concrete as a direct application of the laws

of statics and mechanics of materials.

In addition, it emphasizes that a successful design not only satisfies design rules,

but also is capable of being built in a timely fashion and for a reasonable cost.

A multi-tiered approach makes Reinforced Concrete: Mechanics and Design

an outstanding textbook for a variety of university courses on reinforced concrete design.

Topics are normally introduced at a fundamental level, and then move tohigher

levels where prior educational experience and the development of engineering

judgment will be required.

This is probably the best textbook for reinforced concrete design in the market,

especially for the two to three semester sequences of reinforced concrete

courses that are taught at universities.

It provides many in-depth examples and clearly explains

all procedures in a very concise manner, making the textbook very readable.

The authors also spent a lot of time discussing the MECHANICS of reinforced concrete,

which is something that many other textbooks do not thoroughly cover.

I would highly recommend this textbook to any student in Structural Engineering.

It is also serves as an excellent reference for practicing structural engineers.

You will not be disappointed when you read this textbook.

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Contiguous Piled Wall With Ground Anchor Support Design Spreadsheet

Contiguous Piles, structures made of piles, and pile-like structures are useful structural elements to support deep excavations and cuts in slopes, and to retain creeping or sliding slopes, not uncommonly in seismic areas.

Depending on the static system and the dimensions the structural elements transfer forcesmainly by shear (“dowel”) and/or mainly by bending (“beam”) to the ground.

In numerous cases they are particularly effective in combination with otherstructural measures like (pre-stressed)

anchors and/or drainage systems. The paper presents case histories including piles and pile-like structures, which are applied for retaining structures in slopes.

The main focus is on infrastructureprojects in creeping slopes. Two case historiesfrom Austria and Sloveniaare presented in detail. Miscellaneous projects from European countries concentrating on various aspects complement

the contribution.

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New Bridge Composite Twice as Strong as Concrete and Steel

The University of Maine’s Advanced Structures and Composites Center tests the strength of their new composite girders at a ceremony on July 12th. (Image courtesy of University of Maine.)

Researchers at the University of Maine have developed a lightweight composite bridge that is twice as strong as steel and concrete bridge girders.

In a mid-July demonstration, the university’s Advanced Structures and Composites Center tested a 21-foot span of the composite with computer-controlled hydraulic equipment that can simulate the weight of highway traffic. The test was necessary to ensure that the bridge passed American Association of State Highway and Transportation Officials (AASHTO) Bridge Design Specifications, and it succeeded with flying colours.

“Today’s bridge test exceeded our expectations,” said Habib Dagher, executive director of the Center. “The composite bridge withstood forces equivalent to more than 80 cars stacked on top of each other, and more than 5 times the HL 93 design load specified by AASHTO. The composite bridge girder exceeded twice the collapse strength of steel and concrete girders.”

The design is made up of lightweight composite FRP girders connected to precast concrete panels, a system which the team says can allow a bridge to be built in as little as three days. The composite is an undisclosed blend that involves thermoset resin, glass fiber and carbon fiber, which means that the girders are relatively light (approximately 1-2 tons for 40- to 80-foot spans). The lighter weight makes the bridge easier to ship, as does the “stackable” shape of the girders. To Dagher and his team, the ease of transport was an important consideration: “Our design philosophy has been to look at the entire lifecycle.”

The test came a little over a month after the US Department of Transportation announced that they would grant UMaine up to $14.2 million to lead a push to improve the durability of New England’s transportation infrastructure. And it looks like the bridge will stand up to the challenge. According to the team, the girders are designed to last for up to 100 years, and the panels are relatively easy to replace. “The unique connection system we’ve developed allows you to come in 50 years later, essentially pull the deck out and then put the new deck on without having to jackhammer the concrete deck like you typically would,” Dagher said.

The Center is also responsible for the famous Bridge-In-A-Backpack, a lightweight FRP composite structure to reinforce arch bridges. And Advanced Infrastructure Technologies, the company that licensed Bridge-in-a-Backpack, is looking forward to licencing the new composite after another round of trials in August.

“As the commercialization partner of the Center’s composite arch bridge system, today’s event allowed us to showcase this new technology with potential investors as well as DOT partners and executives,” said Brit Svoboda, chairman and CEO of AIT Bridges, on the day of the trial. “We’re ready to go to market.”

Source : www.engineering.com

Dams and Appurtenant Hydraulic Structures

Water, one of the few natural resources without which there is no life, is distributed throughout the world unevenly in terms of place, season and quality. For this reason it is essential to construct dams on rivers, thus forming reservoirs for the storage and the even use of water.

To date, forty-two thousand large dams have been built worldwide, and hundreds of thousands of smaller ones, which have made possible a rational use of a certain amount of river water – the most important water resource for human life and activity. Dams, together with their appurtenant hydraulic structures, belong among the most complex engineering works, above all because of their interaction with the water, their great influence on the environment and their high cost.

Therefore great significance is given to theoretical research relating to dams, to improving the methods of analysing and constructing them, and to the knowledge gained in the course of their exploitation. In the past forty years great progress has been made in this respect.

Water plays an exceptionally significant role in the economy and in the life of all countries. It is of crucial importance to the existence of people, animals, and vegetation. The settling of people in different regions of the Earth has always been closely dependant on the possibilities for water supply, parallel with those for providing food, shelter, and heat.

The increase in population, as well as the development and enrichment of mankind, in a number of places has reached a level at which the water supply, needed for the population, industry, irrigation, and production of electric power, has been brought to a critical point.

On the other hand, reserves of water on Earth are very large. They have been estimated to amount to 1.45 billion km3 (Grishin et al., 1979). If we assume that the above quantity of water is uniformly spread over the Earth’s surface, then the thickness of such a water layer would be almost 3,000 m. As much as 90% of that quantity is attributable to the water of oceans and seas, while the remainder of barely 10% belongs to lakes, rivers, underground waters, and glaciers, as well as moisture from water in the atmosphere. Only 1/5 of the freshwater, which is suitable for man’s life and activities, is available for use.

More than twenty large dams and over a hundred smaller ones have been built in the Republic of Macedonia, which have still only partially exploited the available water, and flood control remains incomplete. The majority of the large dams were built in the period from 1952 to 1982 while, principally because of the lack of investment, the past twenty years have seen the construction mainly of smaller dams with a height of up to twenty metres and a reservoir volume of 300,000 cubic metres.

In the next few years some two or three more large dams will be completed which will still not
satisfy the need for water for the water supply, for irrigation and for the production of electrical energy, which are continually on the increase. The situation in all developing countries is similar, so that dams will continue to be built in the future despite the resistance on the part of devotees of the unobstructed flow of rivers.

An important unfavourable circumstance, which renders difficult a more complete utilization of water, is the fact that it is very not uniformly distributed on the Earth’s surface – considering space, time, and quality. That is to say, particular countries and regions suffer from drought, while others possess too large quantities of water. Also, the very same region could, in the course of a particular period of the year, be exposed to drought, while suffering from floods in another period. In that way, water, that common nationwide wealth without which no life is possible, can be an irreplaceable friend to man, but also his great enemy if he is not able to utilize it in a correct manner and to keep it under control.

Hydraulic land reclamation, i.e. irrigation of land, or else drainage of excess water from a specific territory. At the moment, irrigation systems cover approximately 270 × 106 ha, or 20% of the total cultivated areas. In many countries, especially in developing ones, increased food production is only possible by improving or increasing irrigation. The greatest amount of water is spent on irrigation – 3⁄4 of total consumption in the world. Great efforts are made to develop effective ways of saving water by avoiding losses in distribution networks and by applying more skillful irrigation techniques.

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Dam Failures and Incidents

I. Reasons Dams Fail

Dams can fail for one or a combination of the following reasons:

1. Overtopping caused by water spilling over the top of a dam. Overtopping of a dam is often a precursor of dam failure. National statistics show that overtopping due to inadequate spillway design, debris blockage of spillways, or settlement of the dam crest account for approximately 34% of all U.S. dam failures.

2. Foundation Defects, including settlement and slope instability, cause about 30% of all dam failures.

3. Cracking caused by movements like the natural settling of a dam.

4. Inadequate maintenance and upkeep.

5. Piping is when seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam. [See an animation of a piping failure.] Another 20% of U.S. dam failures have been caused by piping (internal erosion caused by seepage). Seepage often occurs around hydraulic structures, such as pipes and spillways; through animal burrows; around roots of woody vegetation; and through cracks in dams, dam appurtenances, and dam foundations.

II. History of dam failures around the world

Here are some cases of dam failures around the world

1. Malpasset arch dam failure in France in 1959 (421 deaths)

The causes:

High uplift pressures following heavy rainfall & a weakness in the left abutment rock

Lessons learnt:

Appropriate SI and assessment by experts in all areas of dam design

2. Vaiont dam overtopping incident in Italy in 1963 (2600 deaths)

The causes:

Instability of reservoir slopes causing a landslip & 125m high wave over the dam

Lessons learnt:

Measure pore water pressures & movements at depth as well as at the surface

3. Dale Dyke dam breach in 1864 ( 244 deaths )

The causes:

Internal erosion possibly caused by hydraulic fracture of the core

Lessons learnt :

Designs include wider cores, use of cohesive & compacted fill and placing pipes in tunnels through natural ground

4. Eigiau & Coedty dam failures in 1925 (16 deaths)

The causes :

Foundation failure of Eigiau & overtopping failure of Coedty

Lessons learnt :

Dams need to be designed, supervised and inspected by qualified engineers

Slide Failure at Dam – Association of State Dam Safety Officials (ASDSO)