Concept Design of Foundation

Builders have realized the need for stable foundations since structures began rising above the ground. Builders in the time of the Greeks and the Romans certainly understood the need for an adequate foundation because many of their structures have remained unyielding for centuries. Portions of Roman aqueducts that carried water by gravity over large distances remain today. The Romans used stone blocks to create arched structures many meters in height that continue to stand without obvious settlement. The beautiful Pantheon, with a dome that rises 142 ft above the floor, remains steady as a tribute to builders in the time of Agrippa and Hadrian. The Colosseum in Rome, the massive buildings at Baalbek, and the Parthenon in Athens are ancient structures that would be unchanged today except for vandalism or possibly earthquakes.
Perhaps the most famous foundations of history are those of the Roman roads. The modern technique of drainage was employed. The courses below a surface course of closely fitted flat paving stones were a base of crushed stone, followed by flat slabs set in mortar, and finally rubble. The roads provided a secure means of surface transportation to far-flung provinces and accounted significantly for Roman domination for many centuries. Some portions of the Roman roads remain in use today.


Concept in design may divided by 8 phases :

1. Visit the Site
   Not only can information be gained about the geology of the area, but other features of the site can also be considered. The topography, evidence of erosion, possible response of the foundations of existing structures, and accessibility of construction equipment are items of interest. The engineer will wish to consult with local building authorities to get information on criteria with regard to requirements for new construction. The locations of underground utilities should be obtained from the relevant agencies prior to the visit, and the presence of overhead lines should be observed.
2. Obtain Information on Geology at Site
   Except for the very small job where foundation design is straightforward, the engineer will want to employ the appropriate standard of care by obtaining available information on the geology at the proposed construction site.
3. Obtain Information on Magnitude and Nature of Loads on Foundation
   Obtaining information on the magnitude of the loads to be sustained by a structure would seem to be simple, but such is not the case. In many instances, when foundations are being designed, the structural design is continuing. Furthermore, a substantial difference exists between the factor of safety being employed by the structural engineer and by the foundation engineer. The foundation engineer wishes to know the working load to be sustained by the structure, which means the unfactored dead load and live load. Then the working load is factored upward to design the foundation, with the selected factor accounting principally for the uncertainties associated with the soil properties and the analytical procedure being employed.
   In many instances, statistics play an important role in determining loads on a structure. Offshore structures are designed to resist the largest storm that may occur once in perhaps 100 years. Offshore and onshore structures maybe designed to resist the maximum earthquake that could occur in the location of the proposed structure.
   If uncertainties exist in determining the magnitude of the loading, detailed discussions are in order among the various engineers, probably including representatives of the owner of the structure. A detailed discussion of the safety factor, including formal recommendations by agencies that employ load-andresistance-factor design (LRFD), is strongly advised.
   Two principal problems for the foundation engineer are the adequacy of the analytical technique to be employed and the adequacy of the properties of the soil to reflect the behavior of the soil in supporting the structure.
4. Obtain Information on Properties of Soil at Site
   If possible, a staged investigation should be employed, with the first stage aimed at identification and classification of the soils at the site. The selection of the foundation, whether shallow or deep, could be based on the results of the first-stage investigation. The second stage would focus on determining the necessary properties for the design. The work in the second stage could be minor or extensive, depending on the nature of the design and the soils at the site.
   A conceptual curve can be plotted to show how the total cost of a structure can be influenced by the cost of the investigation of the soils. At some stage, the maximum amount of information could be gained to minimize the cost of the structure. Most subsurface investigations do not allow for the optimum approach due to either time or cost constraints. The knowledgeable foundation engineer will benefit the owner and all other professionals on the job by presenting lucid and convincing arguments for a subsurface investigation that
   is fully adequate.
5. Consider of Long-Term Effects
   The foundation engineer is obligated to consider effects on the structure that could occur with time. Examples are settlement due to consolidation of clays, settlement due to compaction of sand by vibration, movement of a foundation due to swelling and shrinkage of a clay, and the adverse effects of timerelated erosion.
6. Pay Attention to Analysis
   The methods of analysis presented in this book contain many equations that include parameters dependent on soil properties. The available computer programs are so efficient that parametric studies can be undertaken and completed in a short time. The engineer is obligated to study the methods proposed to gain a full understanding of the purpose and appropriateness of the procedure. Full advantage should be taken of the speed of modern
   computers. A simple study that is always worthwhile is to use the results of the subsurface investigation and to select lower-bound and upper-bound values of the relevant parameters. Analyses can be made with the two sets of data to allow the selection of properties to be used in the final design.
7. Provide Recommendations for Tests of Deep Foundations
   Studies of the design of foundations at a particular site may indicate the need to perform a full-scale load test of the deep foundation to be employed in the construction. A justification for the test would be that no data are available on the performance of the type of foundation to be used in the soil that exists at the site. A further justification exists if the engineer can show that the cost of the deep foundations to be used without the test would be reduced by more than the cost of the test if testing is approved.
8. Observe the Behavior of the Foundation of a Completed Structure
   Some very successful foundation engineers have made extensive use of formal observation. This will allow corrections to be made if the observation shows deficiencies. Even if formal observation is not employed, many engineers make an effort, with the consent of the owner, to observe the performance of the foundation with time. On some occasions, instruments may be used to gain information on the distribution of loading to the various elements of the foundation. Such information is extremely valuable.
   

soil, geotechnical, civil engineering, site, foundation

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Prestressed Concrete

Reinforced concrete is the most widely used structural material of the 20th century. Because the tensile strength of concrete is low, steel bars are embedded in the concrete to carry all internal tensile forces. Tensile forces may be caused by imposed loads or deformations, or by load-independent effects such as temperature changes or shrinkage.

Figure 1
Consider the simple reinforced concrete beam shown in Figure 1. The external loads
cause tension in the bottom fibres which may lead to cracking, as shown. Practical reinforced concrete beams are usually cracked under the day-to-day service loads. On a cracked crosssection, the applied moment is resisted by compression in the concrete above the crack and tension in the bonded reinforcing steel. Although the steel reinforcement provides the cracked concrete beam with flexural strength, it does not prevent cracking and does not prevent the loss of stiffness caused by cracking. Crack widths are approximately proportional to the strain, and hence stress, in the reinforcement. Steel stresses must therefore be limited to some appropriately low value in order to avoid excessively wide cracks. Similarly, large steel strain is the result of large curvature, which in turn is associated with large deflection. There is little benefit to be gained, therefore, by using higher strength steel or concrete, since in order to satisfy serviceability requirements, the increased strain capacity afforded by higher strength steel cannot be utilized.

Prestressed concrete is a particular form of reinforced concrete. Prestressing involves the application of an initial compressive load on a structure to reduce or eliminate the internal tensile forces and thereby control or eliminate cracking. The initial compressive load is imposed and sustained by highly tensioned steel reinforcement reacting on the concrete. With cracking reduced or eliminated, a prestressed section is considerably stiffer than the equivalent (usually cracked) reinforced section. Prestressing may also impose internal forces which are of opposite sign to the external loads and may therefore significantly reduce or even eliminate deflection.

With service load behaviour improved, the use of high-strength steel reinforcement and highstrength concrete becomes both economical and structurally efficient. As will be seen subsequently, only steel which can be tensioned with large initial elastic strains is suitable for prestressing concrete. The use of high-strength steel is therefore not only an advantage to prestressed concrete, it is a necessity. Prestressing results in lighter members, longer spans, and an increase in the economical range of application of reinforced concrete.

Prestress is usually imparted to a concrete member by highly tensioned steel reinforcement (wire, strand, or bar) reacting on the concrete. The highstrength prestressing steel is most often tensioned using hydraulic jacks. The tensioning operation may occur before or after the concrete is cast and, accordingly, prestressed members are classified as either pretensioned or post-tensioned.

Figure 2
Figure 2 illustrates the procedures for pretensioning a concrete member. The prestressing tendons are initially tensioned between fixed abutments and anchored. With the formwork in place, the concrete is cast around the highly stressed steel tendons and cured. When the concrete has reached its required strength, the wires are cut or otherwise released from the abutments. As the highly stressed steel attempts to contract, the concrete is compressed.

Prestress is imparted via bond between the steel and the concrete. Pretensioned concrete members are often precast in pretensioning beds long enough to accommodate many identical units simultaneously. To decrease the construction cycle time, steam curing may be employed to facilitate rapid concrete strength gain and the concrete is often stressed within 24 hours of casting. Because the concrete is usually stressed at such an early age, elastic shortening of the concrete and subsequent creep strains tend to be high. This relatively high time-dependent shortening of the concrete causes a significant reduction in the tensile strain in the bonded, prestressing steel and a relatively high loss of prestress.

Figure 3
The procedures for post-tensioning a concrete member are shown in Figure 3. With the formwork in position, the concrete is cast around hollow ducts which are fixed to any desired profile. The steel tendons are usually in place, unstressed in the ducts during the concrete pour, or alternatively may be threaded through the ducts at some later time. When the concrete has reached its required strength, the tendons are tensioned. Tendons may be stressed from one end with the other end anchored or may be stressed from both ends, as shown in Figure 3b. The tendons are then anchored at each stressing end.

The concrete is compressed during the stressing operation and the prestress is maintained after the tendons are anchored by bearing of the end anchorage plates onto the concrete. The post-tensioned tendons also impose a transverse force to the member wherever the direction of the cable changes. After the tendons have been anchored and no further stressing is required, the ducts containing the tendons are often filled with grout under pressure. In this way, the tendons are bonded to the concrete and are more efficient in controlling cracks and providing ultimate strength. Bonded tendons are also less likely to corrode or lead to safety problems if a tendon is subsequently lost or damaged. In some situations, however, particularly in North America and Europe, tendons are not grouted for reasons of economy and remain permanently unbonded.

Most in situ prestressed concrete is post-tensioned. Relatively light and portable hydraulic jacks make on-site post-tensioning an attractive proposition. Post-tensioning is also used for segmental construction of large-span bridge girders.

Prestress may also be imposed on new or existing members using external tendons or such devices as flat jacks. These systems are useful for temporary prestressing operations but may be subject to high time-dependent losses.

concrete, prestressed, civil engineering, steel, tension, compression

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Useful Facebook Tools

Facebook as social networking sites in the world has many tools and Add-ons that can make you comfortable when playing with facebook. Facebook allows users to use applications and even create your own application.

The following 10 Tools and Facebook application that can make you comfortable playing with facebook and easier to manage your facebook.

1. Facebook Mobile
Facebook Mobile is an application that is used by many users. Gives you the ability to upload photos and notes from a camera phone directly to Facebook.

2. Friends Organizer
Friends Organizer is a nifty application that can be used to sort your contacts into groups, such as schoolfriends, work friends, friends of social media etc.

3. Facebook Toolbar
Facebook Toolbar has a search box, a notification, an icon that can be used to check the pictures your friends and status.

4. Simple Photo Uploader
Simple Photo Uploader is a desktop application for facebook that can help you to upload images easily. Simple Photo Uploader also provide the ability to tag photos.

5. FacePad
Facepad is a firefox add-ons that allow you to download the facebook friend and event albums.

6. Advanced Wall
Rather than post messages through the default option, Advanced Wall can post photos, pictures, graffiti, video, flash, change text size and color, along with many other things using the simple WYSIWYG editor.

7. ScrapBoy
ScrapBoy is a desktop application for the facebook application that can be used to do almost everything associated with facebook. With features such as writing a wall post, view photos or Facebook chat, see? Wall? some friends, photo album and chat window at the same time and the other.

8. Graffiti
Graffiti is a Facebook-based application that can be used for drawing on the walls of your friends.

9. Task Master
Task Master allows you to manage your tasks on facebook more efficiently.

10. Last.Fm Music
Last.Fm Music is a music application for all the people who love music and of course Last.fm. This application allows you to compare your music with friends, listening to their songs, and place of the artist and album photo in your profile.

There are still a lot of facebook tools which can make us to connect our friends easier, don't be afraid to try it and you can share it in here anytime you want if you get some problem. See yaaaa.

facebook, social, networking, tools, friends, online, chat

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Google Search Tricks

Searching on Google can be a magical experience once you find out how to make your search queries efficient. By making efficient I mean using some tricks or the cheat sheet provided by Google itself to quickly find what you actually require. Having being hooked onto Google for a long time now, I have come across some amazing search tricks which can change the way you look at Google today.

In this article I will list down the search tricks which I use quite frequently. Be it finding time, meanings or watching the cricket score, searching PDF’s, with Google as the search engine life cannot be more simpler.

Here are the 10 most amazing Google Search tricks:

1. Different Types of Files at your will
How many times would you have asked for materials (PDF, PPT, DOC) for a particular topic from a friend? Its almost everyday that we might have the necessity to ask them either for knowledge, preparing a presentation, white-paper or for case studies. Such times it mostly difficult to look out what to exactly search for because most of the times you don’t know about the topic at hand. But this petty keyword unleashes its lethal power at such occasions.
Let’s say I want to implement a case study on SOA which means I have to read a lot of information for SOA. So I just have to find materials which might have already been uploaded on the web in the form of PDF’s, DOC’s or PPT’s. These materials can be easily obtained by doing a search for:

PDF - service oriented architecture filetype:pdf

PPT - service oriented architecture filetype:ppt

DOC - service oriented architecture filetype:doc

2. Scholarly Search
If you want some authenticity of the materials then it would be better to find the materials from educational institutes or universities. For this use the Google scholar search.But suppose you don’t like to switch to Google scholar search you can add the same query with an additional parameter to the normal Google search box,

service oriented architecture filetype:pdf site:edu

3. Meanings of any word in an instant
Now you do not have to carry a dictionary or install a dictionary software just for the purpose of finding out a meaning of a word. With the wealth of information in Google’s hands, its a piece of cake to find out the meaning of the word. Just use the define: keyword. The meaning would of course be displayed but also a set of other links which might have an alternative definition are also given out with the link to read more about it.

define:beureaucracy

You would argue here that, a dicitionary gives out more information than this. But what about words that don’t actually fall within the vocabulary. Suppose you want to know what SOA (Service Oriented Architecture) is then you would have no choice. Google Search comes to your rescue in this case,

Abbreviations - define: SOA

Jargons - define: Web 2.0

SMS language - define: LOL

4. Find the time of any location
Many of us might be probably working for client which are based at different locations. And communication has to be carried out frequently carried out in such cases. But before a communication you have to know which time zone the location is falling into otherwise you would be causing a disturbance.
I have seen people installing time zone software for showing the time of the location they would be calling to. But with Google at your hands you don’t have to install any software. It would be just simple to use a query for finding the current time such as,

time new york

psst….look closely the time on the little clock graphic. It also shows the perfect time!

5. Weather at your fingertips
I had been to GOA for a Christmas vacation in the last week of December. But I made a mistake of not finding out the temperature of GOA before leaving. Had I known that it is hot even in the winter I would not have made the mistake of carrying additional luggage consisting of blankets and jackets.
If you are thinking to visit a place it is useful to know what the temperature of the place is before hand, it can make efficient packing. Google helps you here too.
Just use this query without asking anybody or waiting for the news to make a weather report. I wish I had thought of this!

goa weather

6. Google does live commentary too!
Indians are cricket fanatics. But its amusing to see the organizations here trying to put together tactics to devoid cricket lovers from wasting time to watch the cricket scores instead of doing their work. What I think they fail to understand is that by blocking the live cricket scoring sites they are actually making the employees more curios and provoking them to hunt for proxy networks or listen to the radio or chat with their friends elsewhere.
Jokes apart, you actually don’t need proxy networks to view the live cricket scores if you at least have access to Google. If you want to find the latest info about all the cricket matches then just type,

cricket

But if you want to find out only about a particular match then use only the names of the two playing nations,

India Australia

Remember that the scorecard will come only when the play is going on.

7. Calculate with your browser
Every OS has a calculator inbuilt but when the browser is the thing which is constantly open whey bother to open up a calculator. Open Google and straight away type your mathematical expression. You can go all the way from basic arithmetic to trigonometrical expressions. This is simply amazing stuff accomplished by Google.

26 * 9000

sin(90) / cos (90)

8. Compare your currency with others
Now that the dollar is declining, the rest of the world must be busy trying to check the impact of the dollar on their currencies. But first of all one must know how much a particular currency amounts to when cashed in another currency. Google’s inbuilt currency converter just does this.

1USD in IDR

1EUR in INR

9. Keep track of the stocks
With the booming stock market it is very important to track the stocks on a day to day basis. Putting a stock ticker in the search box is the most obvious thing you would think of. But it is not always you would remember the stock ticker, you should add the keyword “stocks:” to the company name.
The best part of the obtained result is that it provides a chart which shows the trend in the company’s stock along with important statistics.

stocks: INFY

Note: Currently the results are restricted to the companies listed in the US stock markets.

10. Wanna find some faces?
This is most interesting trick. You might be needing images for various occasions and searching for images is the most difficult thing because what we expect might not be possibly mapped to a query. But Google has a parameter in place for images in situations we need an image which describes a face.
Suppose I search for the term “happy” then the Google results page displays smileys. But I would like to use images of happy people. Even if I choose the term as “happy face” the results don’t show images which contain people. For this there is a parameter “imgtype” which you can use with the URL. For this put in the URL as follows:

http://images.google.com/images?q=happy&imgtype=face

There are many more variations which can be bought about with the above tricks thus making your search experience not only enriching but also exciting.
If I have missed any tricks of common usage, feel free to mention it.

google, search, tricks, internet, tutorial, syntax

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Introduction to Bamboo Reinforced Concrete

The use of bamboo as reinforcement in portland cement concrete has been studied extensively by Clemson Agricultural College. Bamboo has been used as a construction material in certain areas for centuries, but its application as reinforcement in concrete had received little attention until the Clemson study.
A study of the feasibility of using bamboo as the reinforcing material in precast concrete elements was conducted at the U. S. Army Engineer Waterways Experiment Station in 1964.
Ultimate strength design procedures, modified to take into account the characteristics of the bamboo reinforcement were used to estimate the ultimate load carrying capacity of the precast concrete elements with bamboo reinforcing.
Bamboo was given recent consideration for use as reinforcement in soil-cement pavement slabs in which the slabs behave inelastically even under light loads. For this case ultimate load analysis was shown to be more economical and suitable for use.
The following factors should be considered in the selection of bamboo culms (whole plants) for use as reinforcement in concrete structures:
1. Use only bamboo showing a pronounced brown color. This will insure that the plant is at least three years old.
2. Select the longest large diameter culms available.
3. Do not use whole culms of green, unseasoned bamboo.
4. Avoid bamboo cut in spring or early summer. These culms are generally weaker due to increased fiber moisture content.

concrete, bamboo, reinforced, steel, tension, compression, civil engineering

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Civil Engineering

Civil engineering is a professional engineering discipline that deals with the design, construction and maintenance of the physical and naturally built environment, including works such as bridges, roads, canals, dams and buildings. Civil engineering is the oldest engineering discipline after military engineering, and it was defined to distinguish non-military engineering from military engineering. It is traditionally broken into several sub-disciplines including environmental engineering, geotechnical engineering, structural engineering, transportation engineering, municipal or urban engineering, water resources engineering, materials engineering, coastal engineering, surveying, and construction engineering. Civil engineering takes place on all levels: in the public sector from municipal through to federal levels, and in the private sector from individual homeowners through to international companies.

civil engineering, basic, geotechnical, structural, surveying, construction

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