Showing posts with label Dictionary. Show all posts
Showing posts with label Dictionary. Show all posts

Tuesday, December 16, 2014

What is Wobble Coefficient in post tensioning system?

Lets us answer this question from scratch, the word wobble means unsteady jerking movement from one end to other or move unevenly while coefficient is a symbol or number that defines the relation between two or more variables.

While post tensioning we use strand wire that is being joined by twisting around one and other to make a tendon, this tendon is to be inserted within a profile pipe called sheathing or duct after the concrete will achieve a specified compressive strength.



Sometimes the jacking force is applied from one end or both ends. The duct or profile pipe is to be inserted as per the designed curvature and location. The strand wire or tendon can’t be completely set as per the designed curvature and profile due to field restrictions and faulty workmanship.


Due to these reasons the curvature is bit shifted from the designed curvature and thus causes some loss in tensioning force. When jacking force is applied at one end, it decreases as we moves to the farther end due to friction between the tendon and the profile pipe or duct, this friction losses is of two types,
1)      Curvature friction loss
2)      Wobble friction loss
Curvature friction loss is basically the loss in tensioning or jacking force due to design curvature while wobble friction or wobble coefficient is a function of unintended deviation due to faulty workmanship or field restrictions.
Wobble coefficient is usually denoted by K and is measured in units of per length. It is found by multiplying the jacking force at any distance from jacking end with the average of the intended angular deviation from the design profile.

Usually having value of 0.0088. 

Tuesday, September 16, 2014

Download The Wiley Dictionary of Civil Engineering and Construction by L.F. Webster

The definitions in the book have been compiled to be of use to those working in a wide range of professions related to civil engineering and trades involving architecture, engineering, surveying building, heavy construction, forestry, surface and open-pit mining, and public works. 
"Download The Wiley Dictionary of Civil Engineering and Construction"

Title of the Book

The Wiley Dictionary of Civil Engineering and Construction
the Wiley Dictionary of Civil Engineering and Construction

Author

L.F. Webster

About the book

Also included are many terms applicable to the tools and equipment employed in those specialties.
The Civil Engineering definitions and descriptions have been kept purposely brief in the expectation that this book will be used as a source of first reference, rather than as a definitive text.
Dictionary in any field of engineering is an essential book to have with oneself. This book of 600+ Pages is a well known book from mid 90s that serves the purpose and is regarded as reference for any term. 
Most of the terms we define here in iamcivilengineer.com related to civil engineering has been defined by this book. Countless words of full explanation will satisfy the appetite of your knowledge and thirst or quest for education. 

Preview of the Book

Here is a live preview of the Wiley Dictionary of Civil Engineering and Construction; 

Download The Wiley Dictionary of Civil Engineering and Construction

Download The Wiley Dictionary of Civil Engineering and Construction for Free just Click any of the link below and enjoy fast one click download free without any registration. 

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Wednesday, September 10, 2014

Fatigue (Alligator) Cracking

The word Fatigue means repetitive action of loads, thus fatigue cracking by names means cracking due to the repetition of loads. As the pavement is subjected to number of vehicles of different sizes and loads the stress keeps on pilling up and thus the cracks appears which are interconnected in nature. 

Development of Fatigue Cracking

The fatigue failure of a pavement consists of 4 states as;
Initiation of minor hairline cracks
Development of micro cracks into wider macroscopic cracks
Propagation of these cracks across the thickness of pavement
Development of Pothole and ultimate premature failure of pavement


Fatigue Failure leading to Development of Pothole

 Fatigue cracking is sometimes also called alligator cracking, as they resembles the shape of the skin of an alligator due to the interconnectedness of the micro cracks in asphaltic pavements. Factors influencing the fatigue cracks 

Factors affecting Fatigue cracking 

There are numerous factors that influence the development of alligator cracks, some of them can be number and magnitude of applied loads, the structural design of pavement including the type of layer materials and thicknesses of various layers, the quality and uniformity of foundation support, How much workable or consistent is the asphalt cement used, the quantity and quality of the asphalt, the presense of air voids and characteristics of the asphalt concrete mix and the last one can be the temperature or the climate condition of the site under consideration.

Problems due to Fatigue Cracking

Due to fatigue cracking there are numerous problems to be faced by the pavement if not proper maintenance is ensure, the structure failure is at the top having, moisture infiltration, roughness and development of pothole are further worse situation inter-related to fatigue cracking.

Causes of Fatigue Cracking

Despite of the fact that fatigue stresses are directly caused because of traffic loading but the factors that can make the situation more worse are the environment factors including weather. 
Similarly due to moisture or any other reason when the subbase or base of the pavement is weakened the pavement will not be able to handle more loads and thus failure would occur.
Sometimes when the drainage characteristics of pavement is not properly optimized the bed of the road degraded causing base or sub-base weakness. 
Sometimes due to poor adhesion between the asphalt and the aggregates, the aggregates started to dislodge from the surface this process is called stripping or raveling due to this exercise same result of fatigue cracking can be observed. 

Fatigue Cracking and Edge Cracking

Alligator Cracking (Fatigue cracking)
Sometimes there is confusion between the edge cracking and fatigue cracking. Both of these are not similar, the basic difference between edge cracking and fatigue cracking is that edge cracking starts from surface and propagate downwards where as fatigue cracking starts from bottom and propagate to the surface. 

Presentation of Fatigue Cracking

As we now, know the reasons of fatigue cracking we can easily prevent them, by making sure the pavement have sufficient resistance against the causing factors, these my include, 
Lowering or reducing the load on asphalt pavement by increasing the thickness of the pavement. 
Provide adequate drainage at the ends and shoulders to avoid collection of water there as well as its percolation into the body of pavement which may worsen the situation. 

How to repair Fatigue Cracking

Similarly like presentation, in repair work one must know the reason of fatigue cracks, but sometimes the specific cause is fairly difficult to determine, and prevention is there correspondingly difficult. Any investigation should involve digging a pit which means coring of the pavement body to determine the structural makeup of the pavement as well as determining whether or not subsurface moisture is a contributing factor. 
While the fatigue crack is in its early stage, crack sealant may heal the bad effects and avoid further damage of the road, but ultimately the crack will propagate and failure will be unavoidable at the end only one solution exists and that is to do overlay of the cracked pavement by a hot Mix asphalt (HMA) of sufficient strength to resist the loading effects. 
According to the conclusion from some of the laboratory tests one can say; for thin asphalt concrete layers which are less than 5 inches, asphalt cement of low stiffness or low viscosity should be used to avoid premature failure due to fatigue, and thus for the asphalt concrete layer of 5 and more than 5 inch thick asphalt cement of high stiffness should be used. 


Monday, September 8, 2014

What is Formwork, Shuttering, Scaffolding, Shouring


During construction of reinforced concrete works as well as their maintenance, we need to support the structure as long as it is in its premature state or plastic state as it could not even bear its own load. After the suitable duration of time, i.e. when concrete sets enough to take its own load, these temporary supports are removed systematically.


Here are some of the definitions that must be known to a construction engineer as well as civil engineer.

What is Formwork:

Concrete construction in the modern building works has achieved considerable importance, roughly speaking 80% of civil engineering works utilize concrete for their constructions. Concrete being plastic material in fresh state, has to kept within an enclosure (moulds) till it gain reasonable strength, this temporary structure which has to be built for any concrete member is called “Formwork”.

shuttering, formwork, scaffolding, shoring


Formwork is thus a sort of mould used for pouring fresh or plastic concrete. It is closed from all sides and can carry the hydrostatic load of fluid concrete, additional load due to vibration, and load of men and machinery. Formwork should be such that it can be easily removed after hardening of concrete.

Timber, plywood panels or steel sheets are used for formwork. Timber is the most common material for formwork construction, it is easy to work with and it is also economical. However the use of steel forms thus gained lot of popularity in the recent years. They can be obtained for all types of structures. The initial cost of steel forms may be high but they can be repeatedly used for a number of times.

What is Shuttering?

Shuttering is a temporary plateform constructed with the help of wooden planks, wooden logs, steel rods or bamboos over which formwork is supported and ultimately pouring of concrete is done.

What is Scaffolding?


Scaffolding is a grid of bamboo, wooden planks or circular steel pipes by which labour can have access to any point of the structure to be constructed and further formwork and shuttering can rest over it. Steel scaffolding is most commonly used as it is easy to dismantle and reassemble.

What is Shoring?

Shoring is the temporary support given to the existing structure for repair purposes. When dismantling any central building, the surrounding building is also temporarily supported.

Tuesday, September 2, 2014

What is Timber, Merits, Demerits Growth and Structure

Variety of Construction Materials are being used now a days depending upon the availability and transportation cost, lesser the material available expensive will be the structure and as a result structural engineer might have to think to change the material accordingly. In mountains where brick is not easily available due to less availability of plain surface timber is preferred, similarly in areas where there is great danger of earthquake and light structure is needed Timber is preferred.  

In this post I will be sharing with you some key terms related to Timber engineering, merits demerits, of timber, growth of trees and structure of trees. It is a series of post related to timber construction so stay tuned for more updates. 
Timber Construction
"In developed nations like the United States, timber is used as lumber in the construction industry and to produce furniture, pulp and paper, and wood-based composites."

Definition of Timber:

“Wood which is suitable for building or any other civil engineering purpose is called Timber”
When it is a port of living tree it is called standing Timber.When that tree has been felled it is called Rough Timber. When it is sawn or converted into various forms it is called “Converted Timber”

Uses of timber

Despite of the aesthetic use of timber for decoration and finishing work, Timber is used as a structural material in houses as well as structural components like beams, columns, slabs etc. Because Timber is easily available in hilly and cold areas it is used for partial and full insulation. Some times Timber is used to construct Small Span bridges as well, we can see many of the bold bridges being that of timber along with the cables. Similarly in past Railway engineers used Timber as sleepers under the railway track to bear the thrust of the steel rail gauges and to provide them stability as well. 

Merits and De-merits of Timber

Timber is cheap and economical as it is easily available, in comparison to concrete where which need specified gradation of aggregates and sand as well which is not readily available in some hilly backward areas. Timber can be cut easily to any shape as required in the shape of column, beam or even you can construct truss out a timber log. Timber is durable and long lasting as far as it is dynamite proof. It is harder and light weight which enhances its ability to be constructed on sites of low bearing capacity soils. 

"Early citizens in the Massachusetts Bay Colony started to refer to sawed planks as lumber"
But Timber has some demerits as well, It can easily be attacked by insects which can convert whole of the structure into powder just in few days. Moisture and water logging problems in few areas are destructive for it. It is less strong as compared to steel and concrete. In some plain areas it is very costly and environmental hazards and new environmental laws and regulations do not appreciate its usage. 


Classification of Timber (Trees)


There are two types of trees depending upon their mode of growth;
Endogenous 

Exogenous

Endogenous

They grow inward in longitudinal fibrous mass. Examples are banana, bamboo, palm and cane.Their stem is rough and light yet it is flexible enough to be useful for engineers.

Exogenous 

They grow outward by the addition of one concentric ring every year. These concentric rings are called annual rings. The no of concentric rings indicates no of years or age of that tree. Exogenous trees are mostly used for engineering purpose.

Exogenous trees are further classified into two types;
a) Trees yielding soft wood, 
        a. Conifers or evergreen
        b. Trees with pointed leaves
        c. Deodar, pine, chir, kail belong to this group
b) Trees yielding hard wood,
        a. Deciduous with broad leaves
        b. Teak, sal, shisham belong to this group


Growth and Structure of Timber Trees


The growth is done in summer and autumn season;

In spring, roots suck a solution of salt from the soil, this solution is than transmitted to the branches and leaves. The salt solution losses moisture because of evaporation, then it absorbs carbon dioxide from the atmosphere, then in the presence of sun light this solution is transformed into a viscous solution called a sap.

In autumn this sap is descend below the bark where it gets thick and its transformed into wood forming a cambium layer. Cambium layer is again with the passage of time gets thicker and thicker and is then form an annual ring. The modullary rays carry the sap from inside the bark to the interior of tree getting itself nourished. 


Structure of Timber Construction
The cross-section of the an exogenous trees shows the following structure
i) Pith or Medalla
ii) Annual Rings
iii) Heart wood
iv) Sap wood
v) Cambium layer
vi) Medullary rays
vii) Bark

Pith


The first formed round dark portion of the tree is called pith, around pith annual rings are formed the pith, when the plant is young contains large amount of fluid and it nourishes the plant. It dies up and decays when the plant becomes old. 

ANNUAL RINGS

Woody fibre formed and arranged in concentric rings around the pith are called annual rings, they are called annual because each year one ring is developed, with the help of annual rings we can find the age of tree by counting dark or bright rings, each annual ring consists of two parts outer part being darker and inner one being lighter. The outer portion is dark, solid as compared to inner portion. Wood formed during spring season is called spring wood and the wood formed during summer season is called summer wood. 

Bark or Cortex

It is the outermost protective covering of the tree which is exposed to air. 

Heart Wood or Duramen

The central rings surrounding the pith and is near to the pith is generally darker and is called heartwood. It is non-active part of the tree and generally gives rigidity or strength to the trees.

Sap Wood

Ring near to the bark or away from pith is generally lighter in color and is weaker as well, its main task is to provide sap from root to branches. Heart wood  is generally harder than sap wood thus it must be used for all types of engineering works and sap wood must be avoided as is not rigid is more exposed or liable for decomposing. 

Cambium Layer

Rings between bark and sap wood constitutes cambium layer, it is that part which is not yet converted into wood. If the cambium layer is exposed to atmosphere by removing the bark it will result in ultimate death of the tree.

Medullary Rays

These are thin horizontal veins radiating from the pith towards the bark. The main purpose of modularly rays is to carry sap from inner to bark, and they also keep the inner or outer rings bound together. 

What is Brick Masonary and some important terms civil engineers must know.

When bricks are laid in mortar in a proper systematic manner, they form a homogeneous mass, which can withstand forces without disintegration. This mass of the structure, so made by the use of bricks is called "Brick Masonry" or simply "Brick work".

Bricks are of uniform size and shape, light in weight, durable, fire resistant, have high resale value, low maintenance cost and are easily available in plain areas.

Brick Masonry is commonly used for construction of ordinary as well as important buildings in plain areas now-a-days.

Some Important Terms Used in Brick Masonry

What is Brick Masonry?

(1) BRICK

An artificial structural element in the form of a rectangular block of clay is called a “Brick ".

Bricks can be manufactured of any required shape and size. The sizes of some standard bricks are given as follows:


These sizes are called "Nominal, designated or format sizes" and are used while estimating the number of bricks in a given volume of structure.
The actual sizes in which bricks are manufactured, are slightly smaller to allow for the layer of mortar present all around the brick, usually taken as 3/8 in thick. The Actual or Work size of English standard brick, which is mostly used in Pakistan, is usually taken as 8 5/8 in 4 1/8 in x  2 5/8 in.

(2) FROG

The depression provided in the face of a brick is called a "Frog". 

It is provided in the brick to achieve the following purposes:

(a) To form a key of mortar in between any two adjacent courses of brick work, so as to increase the lateral strength of the structure.

(b) To reduce the weight of the bricks, so that the bricks can be laid with convenience.

(c) To provide a place for putting the impression of trade-mark or the year of manufacturing of the bricks.

(3) POSITION OF BRICKS

(a) The position of brick, when laid with its Frog upward in the horizontal plane, is termed as "Brick on bed".
(b) The position of the brick when laid on its side "9 in  x  3 in", with frog in the vertical plane is called "Brick on edge".
(c) The position of brick when laid on its side "4 1/2 in  x  3 in", with frog in the vertical plane is called
"Brick on end".

(4) COURSE

Each horizontal layer of bricks laid in mortar in a brick work is called a "course".

(5) STRETCHER

Brick, laid with its length horizontal and parallel with the face of the wall or other masonry member is called a "Stretcher" 
and a course, in which, all the bricks are laid as Stretchers is called a “Stretching course" or "Stretcher course".

(6) HEADER

A brick laid, so that only its end shows on the face of a wall is called a "Header" and a course, in which all the bricks are laid as headers, is known as "Heading Course" or "Header course".

(7) QUOIN


The external corner of the wall is called a "Quoin".

(8) QUOIN BRICK


The brick, which forms the external corner of a wall is known as "Quoin brick".

(9) QUOIN HEADER

A corner header, in the face of wall, which is a stretcher in the side wall is known as "Quoin header".

(10) QUOIN STRETCHER

A corner stretcher in the face of a wall, which is header in the side wall is known as "Quoin stretcher".

(11) BRICK BATS


The pieces of bricks, cut long their length and having width equivalent to that of a full or half brick are called "Brick bats".

Some common Brick Bats are shown below:

(12) QUEEN CLOSER

Queen closer is a brick, which is half as wide as full brick and is made by cutting a whole brick lengthwise into two portions.
These are generally used next to the Quoin header for creating bonds in brickwork.

(13) KING CLOSER

A brick, whose one diagonal piece is cut off one corner by a vertical plane passing through the center of one end to the center of one side.

It is actually 7/8 of a full brick but is usually called a 3/4 brick


(14) BEVELED CLOSER

A brick cut longitudinally along a vertical plane, starting at the middle of one end to the far corner.
One quarter of the brick is cut off in this way.
           

(15) BULL NOSE BRICK

 
A  brick with rounded corners is called a “Bull Nose Brick”
                               

(16) SQUINT BRICKS

These bricks are used to construct acute (>90 degree) or obtuse (< 90 degree) corners in brick masonry.
These are special forms of bricks.


(17) JAMB

The vertical sides of door or window openings provided in a wall are known as "Jambs".

(18) REVEALS


The part of the Jamb opening , which is exposed between a door or window frame and the face or back of a wall is known as "Reveal".

(19) SILL

The horizontal part (either of timber, concrete, stone, metal, etc) at the bottom of a door or window, supporting the vertical members of the frame is known as " Sill " and its height window base from the floor level is known as " Sill level ".

(20) MORTAR

The paste obtained by mixing a binding material and a fine aggregate in suitable proportions in addition to water is known as "Mortar".

Cement and Lime are used as binding materials and Sand, Surkhi, Cinder, etc. are used as fine aggregates. The mortars are named according to the type of binding material used in their preparation such as, cement mortar, lime mortar, etc. The mortar prepared from simple earth is known as "Mud Mortar". The mortar not only acts as a cementing bed between any two courses of bricks but also, gives strength to the structure by holding the individual bricks together to act as a homogeneous mass.


Credits

These notes have been developed by Prof. Dr. Liaqat Ali Qureshi (UET, Taxila Pakistan)

Friday, August 29, 2014

What is slab?

Structural Concrete Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by structural steel beams, by columns, or by the ground. The depth of a slab is usually very small compared to its span.

What is a slab? Or Slab System?


Firstly we should not confuse this word with SLAB which is acronym of Slow Low and Bangin which is mainly used in the south for any car that is fully customized.
Concrete slab is a common structural element of modern building. That is usually horizontal and has smaller thickness comparative of its span.

Slabs are used to furnish a flat and useful surface in reinforced concrete construction.

Classification or Type of Concrete Slab


In general, slabs are classified as being one-way or two-way. Slabs that primarily deflect in one direction are referred to as one-way slabs. When slabs are supported by columns arranged generally in rows so that the slabs can deflect in two directions they are usually referred to as two-way slabs.

One way and two way slabs


One more definition regarding one-way and two –way slab is that if one direction span to other direction span ratio (or more precisely if longer dimension to shorter dimension ratio) is greater than 2 it is termed as two way slab, otherwise if less than two it is termed as two-way slab.
One way slab with beams
two-way slab with beams

Classification of Two way Slabs


Two way slabs may be strengthened by the addition of beams between the columns, by thickening the slabs around the columns (drop Panels), and by flaring the columns under the slabs (Column Capitals).

Flat Plates Slab Definition 


These are solid concrete slabs of uniform depths that transfer loads directly to the supporting columns without the aid of beams or capitals or drop panels.
flat plate

Flat Slabs Definition 


Flat slabs include two-way reinforced concrete slabs with capitals, drop panels, or both. These slabs are very satisfactory for heavy loads and long spans. Although the formwork is more expensive than for flat plates, flat slabs will require less concrete and reinforcing than would be required for flat plates with the same loads and spans. They are particularly economical for warehouses, parking and industrial buildings, and similar structures where exposed drop panels or capitals are acceptable.
Flat Slab

Flat slabs Vs Flat Plate Slabs



  • Flat plate slabs can be constructed quickly due to their simple form work and reinforcing bar arrangements. 
  • They need the smallest overall story heights to provide specified headroom requirements, and they give the most flexibility in the arrangement of columns and partitions. 
  • They also provide little obstruction to light and have high fire resistance because there are few sharp corners where spalling of concrete might occur. 
  • Flat plates are probably the most commonly used slab system today for multistory reinforced concrete hotels, motels, apartment houses, hospitals, and dormitories. 
  • Flat plat slabs present a possible problem in transferring the shear at the perimeter of the columns. In other words, there is a danger that the columns may punch through the slabs. 
  • As a result it is frequently necessary to increase column sizes or slab thickness or to use shear heads. Shearheads consist of steel I or channel shapes placed in the slab over the columns. 
  • Although such procedures may seem expensive, it is noted that the simple formwork required for flat plates will usually result in such economical construction that the extra costs required for shearheads are more than canceled. For heavy industrial loads or long spans, however, some other type of floor system may b required. 



Beam supported slab Definition


A two-way slab with beams is a type of floor system is obviously used where its cost is less than the costs of flat plates or flat slabs. In other words, when the loads or spans or both become quite large, the slab thickness and column sizes required for flat plates or flat slabs are of such magnitude that it is more economical to use two-way slabs with beams, despite the higher form work costs.

Friday, August 1, 2014

Download MS Project Full Project Management Software for MS Office

Project Management in general or construction management in particular is a very significant and important part of any civil engineering projects that includes labour, activities that has specific duration and some resources like machinery or time as well. A project by  a particular definition can be defined as;




What is Project

A project is a set of connected activities that have duration and a single goal that has to be completed in time and according to specification.


What is Project Management


Typical Project Management includes following;
•    Work breakdown structure
•    Project network of activities
•    Critical path method (CPM)
•    Resource management
•    Resource leveling
•    Risk assessment

Different techniques are employed to do the management in a project like PERT (program Evaluation and Review technique) method, CPM (critical Path Method). These all techniques include lengthy calculation and are very hectic to do that by hand.

Project Management and MS Project

 

So for our ease different companies have made Project Management tools like Primavera by Oracle and MS Project by Microsoft. They have a very easy to use interface where you can solve the network diagrams on a single click and generate important reports like gantt chart etc. Also you can perform typical project management activities like Scheduling and Crashing of activities etc.
In this post I am sharing with you very basic and easy to use software for project management i.e. Microsoft Project 2007 or MS Project 2007 it is a MS Office by part that comes with variety of diversity and functionality.



MS Project and Civil Engineering



In field of civil engineering both softwares are used i.e. Primavera and MS Project but most companies prefers Primavera which is a bit professional than MS office. But before you go to learn Primavera its very handy to learn MS Project for your basic knowledge.

MS project sometimes referred as MS Office Project is an Office compatible Project Management tool that helps users to set realistic goals for project teams and customers by creating schedules, distributing and assigning project resources, managing budgets. It helps you in generating reports and charts. MS Project comes with customizable wizard that walks users through the process of Project creation, from assigning their task and resources to reporting the final results.
Typical Gantt Chart in MS Project 2007

About the download (MS Project 2007)

 

This download includes 485 MB *.Zip file that has the main setup file along with the Serial Numbers and Keygen that is required.
The version of the software is 2007 so you might need MS Office 2007 installed. This version is the most stable version than others like 2010 and 2013, we will be sharing them soon as well.

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Download MS Project 2007 Full

 

To download MS Project 2007 full click the following button.
Click here to download

From Editor's Desk

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Friday, July 4, 2014

What is Liquidated damages? What are its clauses

Monetary compensation for a loss, detriment, or injury to a person or a person's rights or property, awarded by a court judgment or by a contract stipulation regarding violation of contract.

Definition

Cash compensation, agreed to by signed, written contract for breach of contract, payable to the aggrieved party. {Law Dictionary: (Black's Law Dictionary}

Generally, contracts that involve the exchange of money or the promise of performance have a liquidated damages stipulation. The purpose of this stipulation is to establish a predetermined sum that must be paid if a party fails to perform as promised.

Conditions when Liquidated damages are imposed:

Damages can be liquidated in a contract only if
1)    First, the amount of the damages identified must roughly approximate the damages likely to fall upon the party seeking the benefit of the term.

2)        Second, the damages must be sufficiently uncertain at the time the contract is made that such a clause will likely save both parties the future difficulty of estimating damages.

Difference between liquidated damages and un-liquidated damages (penalty)

At common law, a liquidated damages clause will not be enforced if its purpose is to punish the wrongdoer/party in breach rather than to compensate the injured party (in which case it is referred to as a penal or penalty clause).

A penalty will be imposed if the loss or damage is reasonably certain if it’s uncertain then liquidated damages clause will be imposed.

Examples of liquidated damage

For example, suppose Saad Iqbal agrees to lease a store-front to Zubair Saleem, from which Zubair intends to sell jewelry. If Saad breaches the contract by refusing to lease the store-front at the appointed time, it will be difficult to determine what profits Zubair will have lost because the success of newly created small businesses is highly uncertain. This, therefore, would be an appropriate circumstance for Zubair to insist upon a liquidated damages clause in case Saad fails to perform.

Undisclosed source code has value as a trade secret. Openly publishing the source code destroys the trade secret value. The trade secret value of source code is difficult or impossible to prove. There is no open market for "secret source code".

In the case of construction contracts, courts have occasionally refused to enforce liquidated damages provisions when both parties have contributed to the overall delay of the project.

Friday, April 11, 2014

What is finite element analysis and how many types are used in analysis and design of concrete structures

Advancements in the field of computer aided engineering during the last two decades have been quite extensive and have led to considerable benefits to many engineering industries. Similarly the advantages can also be observed in the building industry where the softwares and tools which uses finite element have allowed the introduction of innovative and efficient building products along with development of accurate design methods.
Finite Element Analysis

Definition of Finite Element Analysis

According to one definition;
Finite element method (FEM) is a technique for numerical solution of complex structural problems. In this method the structural system (consisting of all the elements which make up a structure) is modeled by a set of appropriate finite elements which are interconnected at points called nodes. Elements may have physical properties such as thickness, coefficient of thermal expansion, density, compressive strength, yield strength, young’s modulus, shear modulus and Poisson’s ratio.

Use of FEM

Traditionally, engineers have used laboratory testing to investigate the structural behavior of steel building products and systems subject to the expected wind and earthquake loads and to develop appropriate design rules. Laboratory testing was also used to develop new building products and systems. However, such reliance on time consuming and expensive laboratory testing has hindered progress in this area. The product manufacturers and designers often decided on conservative designs in order to avoid expensive and time consuming laboratory testing. However, advances in the field of computer aided engineering during the last two decades have changed this situation significantly in many engineering industries.

The finite element method (FEM) is the dominant discretization technique in structural mechanics. The basic concept in the physical interpretation of the FEM is the subdivision of the mathematical model into disjoint (non-overlapping) components of simple geometry called finite elements or elements for short. The response of each element is expressed in terms of a finite number of degrees of freedom characterized as the value of an unknown function, or functions, at a set of nodal points.

The response of the mathematical model is then considered to be approximated by that of the discrete model obtained by connecting or assembling the collection of all elements. The disconnection-assembly concept occurs naturally when examining many artificial and natural systems. For example, it is easy to visualize an engine, bridge, building, airplane, or skeleton as fabricated from simpler components. Unlike finite difference models, finite elements do not overlap in space.

A typical finite element analysis on a software system requires the following information:
1. Nodal point spatial locations (geometry)
2. Elements connecting the nodal points
3. Mass properties
4. Boundary conditions or restraints
5. Loading or forcing function details
6. Analysis options

Because FEM is a discretization method, the number of degrees of freedom of a FEM model is necessarily finite. They are collected in a column vector called u. This vector is generally called the DOF vector or state vector. The term nodal displacement vector for u is reserved to mechanical applications.
FEM Solution Process

Procedure

1. Divide structure into pieces (elements with nodes) (discretization/meshing)
2. Connect (assemble) the elements at the nodes to form an approximate system of equations for the whole structure (forming element matrices)
3. Solve the system of equations involving unknown quantities at the nodes (e.g., displacements)
4. Calculate desired quantities (e.g., strains and stresses) at selected elements

Basic Theory


The way finite element analysis obtains the temperatures, stresses, flows, or other desired unknown parameters in the finite element model are by minimizing energy functional. Energy functional consists of all the energies associated with the particular finite element model. Based on the law of conservation of energy, the finite element energy functional must equal zero. The finite element method obtains the correct solution for any finite element model by minimizing the energy functional. The minimum of the functional is found by setting the derivative of the functional with respect to the unknown grid point potential for zero. This is based on the principle of virtual work, which states that if a particle is under equilibrium, under a set of a system of forces, then for any displacement, the virtual work is zero. Each finite element will have its own unique energy functional.

Sunday, February 2, 2014

12+ Skills civil engineering students must have

Throughout the four years I have spent in an engineering college I have gone through various challenges and difficult situations where your survival sometimes look difficult for you and you think
“Now it’s the time to leave this world”. Don’t take engineering as easy as sciences or arts, although not any work in this world is easy but civil engineering by no means is easy.

Skills civil engineering students must have

Firstly entering in an engineering college itself is a challenge and if your are among those few lucky ones who have got this change – then be happy now fellow because you have got that potential and you have those solid nerves and patience that is needed ultimately.

Now let me state here the worlds of my heart. “Among the other entire tough engineering disciplines civil engineering is toughest and the most difficult one”; you might laugh at me once, but after you have grinded in the crusher for four years your heart will speak the same sentence. The truth of this sentence can also be observed after counting the number of female students you have with you in your class. :P

One of the very irritating thing you will observe in your starting years is people making statements like
“Civil is chill”
“They have nothing to do except staring at girls”
“They are the poor masons without instruments.”
“They are the only ones…always single……”
And bla bla.

Why you have to face these statements? Answer is simple it is because apparently it feels to others that civil engineering is very easy and one might say “Oh! Yeah! Those poor illiterate contractors can also build a house for me very easily, I dn’t need you!” but the only one standing alone within the fighting ring knows how those punches and kicks feel.
In this post I will be sharing with you the skills and abilities a civil engineering students must have so as to be a successful professional civil engineer for this world.


Patience and Control on Anger

 

Now you have already listened to those statements, results of those statements would only be anger in you; lets first know the reason why patience is needed, listening to teachers for continuous hours without break, listening to the statements of your parents and specially father, bearing the cold irritating behavior of your class fellows, seeing no beauty and colors in your life, and a lot more others. These all factors will make your brain hot, you will easily lose your temper, so you must have some patience and control over it otherwise the results will be problems, fights, more statements, and more anger.
So try to develop an ignoring attitude to what others say, always keeps a smile on your face, remain positive and let other do what they are doing and only thing you can change is yourself, develop yourself as a calm and cool engineer.

Confidence 

 

It is a basic need for being a successful human on this planet. Confidence will cover your inabilities and your weaknesses. It is like if we have a black ball with sun, we will not see it. So if you have confidence you will shine along with all of your weakness. Confidence is needed because you constantly have to give presentations, even in examinations you might have to give vivas; and it is like a short interview in which your instructor will judge and mark you on the basis of your confidence. Similarly to make new friends and to have a healthy communication with them you need confidence. Because it is a professional study where every one might have his/her own opinion and own designs you must have confidence on your abilities and skills to prove yourself right.
You can develop confidence by self-motivating yourself, set an aim and goal for yourself and when you will achieve it you will feel confident, participate in extra-curricular activities, sports and games it will boost up your confidence.

Physically Strong

 

It is the very important requirement and is needed because you in your education have to handle stones, aggregates, crush, heavy manual testing equipment, heavy machines, buckets and so on.
Similarly you have to stand while doing manual drawing for hours, and if on computer using structural and drawing softwares you need have that strong back-bone and strong mental skills to remain active and remain confident.

You in survey might have to handle equipment in rough and tough environment, might be too cold or 
might be too hot, but you have to handle, you must have strong immunity to fight with those extreme weathers and those extreme laboratory environment having smell of burning sulfurs, dusting cement, soil, blasting sounds of breaking steel bars and so much more.
You have to eat well, stay healthy, sleep as required, do exercise, take fruits and juices, protect yourself from unhealthy activities and drugs etc.

Absorb Pressure

It is already being explained why pressure is there, your family might not be that much strong 
economically they might be trusting you to get educated and earn a good livelihood for you and for them and thus they would be trusting you and they will have dozens of expectations for you. You at the other end are facing the odds and difficulties as a front war fighter.  You have to learn skills, softwares, remembers countless figures and countless points in your mind, thick chubby books of hundreds of pages and so on.

Thus you have stay calm, because if you take tension you might not be able to solve questions you will lose hope and will ultimately caught in that fear hole. Try to practice your religion and get those superficial powers in yourself and take help from that motivation.

Good Communication Skills

Civil engineering starts by communication, you in field have to satisfy your clients, you must have 
ability to say what your mind imagines and thinks, you have to constantly stay in touch with contractor and consultant and architects and thus you have to make your point and tell them what is feasible and what not.
In class you might not understand a thing and to ask a question from your instructor you will have to have that strong edge in communication skills, any one even not that much strong technically can excel if he/she has strong communication skills.
Try to talk as much as you can with your friends on facebook, on calls, in real life as well. You in start might have a fear calling a stranger like some service stations or some companies, you must have to overcome that fear to be successful.

Good Drawing skills 

 

Drawing is the language of engineers. You can’t communicate that much with words and writings as 
you can with drawings. You must have strong imagination as what a thing will look like in a different perspective view. You might have to draw elevations, sections and so much. You must be able to use manual drawing tools like T-Square, Set Square. Even if you use AutoCAD, you must have that skill because softwares just helps you they don’t have brain.

Try to sketch anything that interests you, you only need a paper and a pencil and a rubber to initiate creativity. Don’t hesitate that what others will say or how they comment. Just be confident and tell the world you have got skills. 

Strong in Mental Calculation

Calculation is what civil engineers mostly do after eating :P, as you might not have always a pocket calculator your brain must be that much fast in calculation that you might not need calculator very often.
You must be able to sum up or subtract or multiply or divide things on your finger tips. Because in calls your teacher might say “What is the dia of #4 bar” you will say ½” instantly but if you dn’t have that skill you will open up the calculator and say 4/8 = 1/2=0.5 and then say sir “0.5” and up to that time the class might be ended.

Must be rough and tough

 

That totally depends on what sort of field or major you select as your career, but if you hate extreme weathers, and harsh environments your chances for survival will be minimized.

Good Computer Skills

 

Because now a day’s computer has overcome all the calculations, manual drawing and manual structural calculations are now very rare and obsolete. Now engineers use ETABS, STAAD Pro and AutoCAD, and etc. etc. These all require from you a strong computer basic skills, you if have computer phobia that if will be difficult for you, you must start by just playing with it, do experiments, and see what happens. It will be a fun.

Good Convincing Skills


“No one is perfect” but if you have confidence you will say “NO ONE is perfect, and I am that NO ONE”. In civil engineering every field and every task has got variables that are obvious to have different answers for different humans. So you must have that convincing skills to tell others why you answer is more economical and more correct than others. Its like a marketing skills that are obviously required. Because you have to justify yourself.

Time Management

 

Time as we all know is money, you have to use it effectively and efficiently. Try to develop a schedule on daily basis follow it, set goals for each day and fight to achieve that goal.

Common Sense

 

“Civil engineering is an engineering of common sense”, this is the sentence that is being told by most of our teachers. Because in civil engineering whatever we build or whatever we develop it is physical, we don’t play with charges moving and we don’t see them. We play with bricks, aggregates, cement, sand, steel, you name it and we can touch that we can feel that and thus most laws and procedure are physical.
To understand and to imagine you must have a common sense. Like if you are a manager and you have to schedule a project activities, you must not set erecting walls before excavation and foundation design so there the common sense come.
But common sense is not very common :D

From Editor’s Desk

 

Civil engineering is a very interesting and very challenging field. But as it is rightly said, the more difficult the task is, the more beautiful the result will be. So don’t lose hope or don’t let yourself down, Your destiny is a few steps away.
I Hope you’d like the post, lets share it with your friends, there are many options available down there.

Saturday, February 1, 2014

Retaining Walls, the support soil needs to stand up

We know that soil or any other loose granular material has a safe angle of repose at which the soil or material can withstand without any requirement of confinement or support. But due to practical and property restrictions we in some cases need to cut or fill the soil at some unstable angle which if unsupported might cause failure of the slope.
Concrete Retaining Wall

If we provide stable slope rather than steep slope; we might need more space there and sometimes more economy is required; to cater this problem we use the retaining wall to support the material laterally after justifying its usage from economic considerations.
Thus we can define retaining wall;

What is Retaining Wall?

As a structure or a part of structure that holds back and retained the loose material behind within a limited space to provide safety and economy one at the same end.
 Or
McCormac and Nelson defines it as;
Retaining wall is a structure built for the purpose of holding back or retaining or providing one-sided lateral confinement of soil or other loose material.

Aurther H. Nilson and others define the retaining wall as;
Retaining walls are used to hold back masses of earth or other loose material where conditions make it impossible to let those masses assume their natural slopes.

Example Of Retaining Wall

Typical example of the retaining wall might be that of highways; in highways we have restricted property space called the right-of-way and within that limited space we have to provide the required width of the highway by using the cut and fill soil, and there those steep slopes come which needs retaining wall to get that support;

Types of Retaining Walls

Most commonly five types of retaining walls are used named as under;
(a)    Gravity Retaining wall
(b)    Cantilever Retaining Wall
(c)    Counter-fort Retaining wall
(d)    Buttress Retaining wall
(e)    Bridge-abutment type retaining wall

Gravity Retaining Wall;

The Gravity Retaining wall as the name suggests provide support or restraint to the loose material laterally because of its self-weight, it generally doesn’t contain reinforcement and mostly is used for 10 ft height and no more than that because more height will increase the need of more thicker cross-section and ultimately it will not be economical.
Gravity Type Retaining Wall

Cantilever Retaining Wall

Is a reinforced retaining wall that acts like a cantilever beam, it has four parts, the portion of the base slab or footing below the retained material is heel, and the other portion is toe, the vertical wall is called stem and to increase the slide friction key is provided below the base slab or footing.
The weight of the retained soil on the top of heel provides additional stability to the structure. It is mostly used for relatively greater heights upto 10 to 20 ft. 
Cantilever Type Retaining Wall

Counter-fort Retaining Wall

In Counter-fort retaining wall the stem and heel (the portion of the base slab below the retained slow) are joined together by inclined transverse walls at intervals called counterforts, Counterforts are in tension and mostly called counterfort ties. Counterfort retaining wall is mostly used for higher heights up to 25ft or more.
Counter Fort Retaining Wall

Buttress Retaining Wall

Buttress retaining wall is similar to counterfort retaining wall except that the inclined transverse walls are provided at the front of the stem called buttresses and acts like a compression member. Because of this property they are more stable and more economical, but because the buttresses are visible and occupies the space un-necessarily that might be useful if buttresses were not there; thus they are not generally used;
Buttress Retaining Wall

 Bridge Abutment Retaining Wall

It is a wall types bridge abutment, abutment and piers are the column-type structures used to support the deck of the bridge, the first and the last support of the bridge are called abutments because they retains the soil where as other supports are called piers. This type of retaining wall is just a simple cantilever retaining wall except that the bridge deck provides an additional horizontal restraint at the top of the stem. This wall is thus designed as a beam with fixed support at the bottom and simply supported or partially restrained at the top. 
Bridge Abutment Retaining Wall

From Editor’s Desk

Retaining Walls are very sensitive type of structures that protects our infrastructure like highways and roads from land-slides etc and helps us to let the roads be clear for us. In the retaining wall drain pipes are also provided along with pot-holes for reducing the amount of lateral load and to allow the wall to remain stable against overturning and sliding.
Hope you like this post, don’t forget to share it with your friends and colleagues.
Happy Civil Engineering!
 

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