الأحد، 27 أكتوبر 2013

REINFORCING BARS




The most common type of reinforcing steel  is the form of round bars , available in a large range of diameters from about 0.375 to 1.375 in. for ordinary applications and in two heavy bar sizes of about 1.75 and 2.25 in. these bars are furnished with surface deformations for the purpose of increasing resistance to slip between steel and concrete.
For a number of years ASTM standards have included a second designation for bars size , the International System of Units (SI), with the size being identified using the normal diameter in millimeters to limit the number of bar designations, reinforcing bar producers in United States have converted to SI for making the bars

السبت، 9 أبريل 2011

Mechanistic-Empirical Design Method

The most advanced pavement structural design uses a mechanistic-empirical method approach. Unlike an empirical approach, a mechanistic approach seeks explaining phenomena by reference to physical causes. In pavement design, the phenomena are the stresses, strains and deflections within a pavement structure, and the physical causes are the loads and material properties of the pavement structure. The relationship between these phenomena and their physical causes is typically described using a mathematical model.
Various mathematical models we can use.

Along with this mechanistic approach, empirical elements are used when defining what values of the calculated stresses, deflections strains and result in pavement failure.
The relationship between physical phenomena and pavement failure is described by empirically derived equations that compute the number of loading cycles to failure. The basic advantages of a mechanistic-empirical pavement design method over a purely empirical one are:

* It can be used for both existing pavement rehabilitation and new pavement construction.
* It accommodates changing load types.
* It can better characterize materials.
* It uses material properties that relate better to actual pavement performance.
* It provides more reliable performance predictions.
* It better defines the role of construction.
* It accommodates environmental and aging effects on materials.


A mechanistic-empirical approach can also accurately characterize in situ material (including subgrade and existing pavement structures). This is typically done by using a portable device (like a falling weight deflectometer) to make actual field deflection measurements on a pavement structure to be overlaid. These measurements can then be input into equations to determine the existing pavement structural support and the approximate remaining pavement life. This allows for a more realistic design for the given conditions.


So, expert knowledge is required to use mechanistic-empirical approaches; a pavement design expert should be consulted if you are considering its use

الأربعاء، 6 أبريل 2011

Structural engineering is a branch of civil engineering, and its applications are extremely diverse

Superman may be can leap tall buildings with a single bound, but the tall buildings wouldn't be there if it weren't for structural engineers.

Structural engineering is a branch of civil engineering, and its applications are extremely diverse. A great deal of what structural engineers do involves designing things to be built, and then helping to build them: buildings, tunnels, bridges, towers. "Probably 75% of our clients are architects," says Scott McConnell, project manager at the engineering firm of Schoor DePalma in Manalapan, N.J. "Most of what I do is building design. The architect comes up with a building design, and then it's the structural engineer's responsibility to fit the structure to the architecture, and decide on what structural system is best suited to that particular building. We design the beams, the columns, the basic members to make the building stand up."

But a structural engineer might also be involved in the demolition or dismantling of a structure, either permanently or in order to repair it. For both of these processes, they need to know about the forces that act on structures—the stresses put on a bridge by heavy traffic or on a high building by strong winds, or on any structure by seasonal temperature changes or earthquakes.

Structural engineers also inspect buildings, both during and after construction, and oversee the use of the concrete, steel and timber of which they are made. They must also be aware of both obvious and inobvious uses for the structures and how these uses affect its design. "For example, if they're putting in sensitive computer equipment or doing pharmaceutical work, you have to use a floor system that's very stiff and doesn't move much," explains McConnell.

Like all engineers whose work may affect life, health or property, new structural engineers go through a rigorous training process during their first few years of work. This training involves several years of work experience under the supervision of experienced engineers and one or more state examinations, and results in a license as a Professional Engineer (P.E.). This is one profession where an advanced degree is more of a necessity than an option.

"My advice to students is that if they're really committed to structural engineering, they should get their master's degree in structural engineering or civil engineering as quickly as possible," says Terry Blackburn, Ph.D., senior vice president and head of the structural department at Schoor DePalma. "The basic courses at the undergraduate level just can't touch on all the necessary aspects of structural engineering. Your advance in the profession is greatly impaired by not having a master's degree."

Along with technical know-how, a structural engineer needs a host of other skills to be able to interact with professional and nonprofessional co-workers and clients. "Sales ability, public speaking and time management are very important when we have to make contact with clients," says Blackburn. "And problem resolution is a skill that isn't typically taught in engineering schools. But when there's an enormous amount of work that costs a lot of money, that is going on very rapidly, and there are problems, then the problems have to be resolved as quickly as possible."

This branch, like other civil engineers, frequently hold the lives of others in their hands, a point that Blackburn says should be explained early and often to would-be structural engineers. "I know I was very surprised at the amount of responsibility that is piled on an engineer," he says. "It's enormous. You hear about things like the Kansas City skyway collapse. Someone is still personally blaming himself today for that. He has to live with that... It's almost heart-stopping when you get a telephone call from a job and something's gone wrong. I think that at some point in the career of most engineers, it just dawns on them, all the responsibility they've assumed over the years—not just the professional responsibility, but the personal liability, too."

الأحد، 7 فبراير 2010

All About Software Engineering And Development

are engineering, known as SE, is the development, design, maintenance and documentation of software by applying practices and various technologies from fields such as computer science, engineering, application domains, project management, digital asset management and interface design.

The conception, development and verification of a software system is what software engineering is all about. It is necessary to identify, define, realize and verify the resultant software's required characteristics. Necessary testing is required for attributes such as reliability, functionality, testability, maintainability, ease of use, availability and portability. In software engineering, software can be verified to meet these requirements by having design and technical specifications prepared and implemented correctly. The characteristics of the software development process are also important in software engineering. Development itself, development duration and risks in software development are examples of such characteristics.

A computer uses software as part of its system that allows the hardware to operate properly. Software can be system software or application software. System software includes the main operating system and a variety of other utilities that enable the computer and its applications to run. Application software includes the computer programs and relevant documentation responsible for end-user data processing tasks. This kind of software is developed for such tasks as word processing, payroll, inventory and production control.

What Are Shop Drawings?

By Brian M. Curran


I started back in the AEC industry in the late nineties, and it probably wasn't long after that when I first heard the phrase "shop drawings". I'm sure the phrase conjured up pictures in my imagine as I thought about the meaning of that phrase, and now many years later I'll answer the same question that put my imagination in gear back then, namely "What are shop drawings?"

Since I have years of experience in the AEC Industry, through which hands-on I have learned a thing or two about shop drawings, for this article I think the best way to answer the question at hand is to: Do a short web query on the topic, then to quickly parse through a few of the results, and finally to offer up a consolidating statement by tying together my experience and web query results.

With having just mentioned my web search method to collecting some definitions, I actually didn't start on the web, if that makes sense! Rather I first started on my bookshelf and found that The Means Illustrated Construction Dictionary Third Edition Unabridged defined shop drawings as, "Drawings created by a contractor, subcontractor, vendor, manufacturer, or other entity that illustrate construction, materials, dimensions, installation, and other pertinent information for the incorporation of an element or item into the construction."

Then I moved onto the web as I said I would, and dug up two more definitions. The first of my web definitions was from the online AIA Document Commentary, A201-2007 General Conditions of the Contract for Construction which stated in section 3.12.1, "Shop Drawings are drawings, diagrams, schedules and other data specially prepared for the Work by the Contractor or a Subcontractor, Sub-subcontractor, manufacturer, supplier or distributor to illustrate some portion of the Work."

Lastly, my web query results turned up Wikipedia's site. They externally cited R Pietroforte (1997)(PDF), Construction Management & Economics, Taylor & Francis Retrieved 2007-02-23, which gave a definition of, "A shop drawing is a drawing or set of drawings produced by the contractor, supplier, manufacturer, subcontractor, or fabricator."

With these three definitions I have a mini sample set of definitions, so that I can check for consistency amongst them, and compare them to my life's experience within the AEC Industry. Considering just that I think the definitions are fairly consistent, and do pretty good job of explaining what shop drawings are without needing any extra explanation. Regardless though, let me further clarify what the definitions are saying through a hypothetical example.

Lets say that there is a man who wants a 20 story building constructed, and so he hires an Architecture / Engineering firm to put together the construction documents for doing so. Well, the construction documents, which will be taken in hand by a Contractor who will actually construct the building, some times don't have all the information that the Contractor will need in order for him to complete the construction of the building. This is where shop drawings come in. They act as the bridge that fills in the gap between the contract documents and the Contractor.

This example admittedly doesn't cover all the varying scenarios in which shop drawings are used, but I do hope it can be extrapolated upon in order to better understand a different shop drawing situation.

About the author: From New York City Brian M. Curran runs a CAD drafting service that provides outsourced AutoCAD drafting services to AEC industry companies, homeowners and others with CAD drafting needs throughout the entire United States. His CAD services include, but are not limited to: Building Surveys / As-built drawings of: building systems, building elevations, roof plans, floor plans, and reflected ceiling plans. Also, hand sketches converted into AutoCAD format, Paper-to-CAD conversions, structural drawings, steel detailing, rebar placing drawings and construction logistics drawings

Structural Drawings - On Demand Structural Engineering Services

Written by Harvesh Modh
Construction is one of the finest and most fruitful business sectors these days. Perhaps that's why it is gaining more and more popularity. Structural engineering services are most widely used by professionals to get huge benefits in short amount of time. Amongst such structural engineering services, structural drawings are most demanded of all.

What are structural drawings? How can we use them to get effective building designs? - Most common questions in anyone's mind. Structural drawings are set of diagrams, graphical representation of pre-fabricated building components. These drawings illustrate detailed technical specifications about almost every important building component/ part. This includes height, width, angles and dimension specifications.

Pre-fabricated building components are the components that are to be used in construction. Main aim behind preparing structural drawings is to get clear idea about complete information about measures, different dimensions and specifications of various building parts. With such bunch of information in your mind, you will definitely be able to build your proposed building structure in an effective manner.

Structural drawings are useful in many ways such as:
• Structural steel drawings with structural drawings symbols
• Steel fabrication drawings
• Structural steel fabrication
• Structural steel dimensions
• Structural steel framing and structural steel erection
• Custom steel shop drawings, structural building drawings
• Structural drafting drawings, structural steel detailing drawings
• Structural CAD drawings
• CAD drafting and design drawings

Structural engineering services like these structural drawings are generally performed by expert structural engineers. They have excellent domain expertise and relative experience to provide superb structural drawings for professionals such as builders, architects and contractors.

Residential Steel Buildings Will Stand the Test of TimeBy Jordan Laurent

Using steel as the structural element for any kind of building especially a residential building is actually a revolutionary thought considering that man has been programmed to think of a house being built only out of bricks and stone. However, steel has qualities that can beat any kind of building material over the centuries as far as safety and durability as well as aesthetic appeal goes. Residential steel buildings will be able to pass the test of time because of the anti corrosion feature that steel as a material has. This means that you can be rest assured that your home will be safe from all kinds of weather hazards and environmental issues that we are all currently fretting about which might very easily harm other buildings.

That feature is only about the exterior superior quality that residential steel buildings command. But on the interior as well, steel has the strength in its very core and structure that enables it to stand erect and stand strong for much longer than buildings made of any other material. Not only will the steel building be structurally strong, but steel is a material that will surely not be affected by termites and other degenerating influences that eat away a building from the inside, thus making residential steel buildings immune to this kind of a break down as well. It is no wonder therefore, that steel has become now the most sought after material for building construction as a substitute to bricks and stone.