Benefits and drawbacks of steel members

Steel is formed by mixing iron, carbon and other components. Due to its extreme tensile strength and low cost, it is considered as a most vital component that is extensively utilized in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.

The steel provides lots of benefits as follows:

1. The steel members contain high strength. So, the steel members have the ability to withstand extreme loads with relatively light weight and small size of members.
Due to their small size, it becomes easier to deal with and transport steel members.
2. The steel members have strong resistance capacity against gas and water due to their high density power (the unit weight of steel is 7.85kN/m3).
3. The steel members last for prolonged periods due to great and standardized strength and density properties of steel.
4. The steel members are utilized as pre-fabricated members as they can be easily managed, fabricated and constructed.
5. The steel members can be easily disassembled or substituted.
6. The supplementary sections or plates can be added with the existing steel structure and structural components to improve the strength significantly.
7. The steel structures can be examined rapidly and smoothly.

8. It may be reprocessed / recycled in furnaces.
9. This material contains high ductility and it is very effective for earthquake resistance structures.

The drawbacks of steel members are as follows:

1. The steel members are vulnerable to corrosion. To get rid of corrosion, apply painting or other methods.
2. The steel members are expensive.

Source: civilsnapshot.com

Benefits and drawbacks of steel members

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Published By
Arka Roy
http://www.constructioncost.co
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Post Tension Slab and its benefits

Generally, post-tensioned (PT) slabs belong to flat slabs, band beam and slabs or ribbed slabs. PT slabs provide the leaner slab type, as concrete functions to its strengths, mostly being maintained in compression. Longer spans are obtained because of pre-stress, which are also utilized to resist deflections.

Post-tensioned slabs employ high-strength tensioned steel strands to compress the slabs to retain most of the concrete in compression. Reinforcement is arranged to control the compression.

In Post tension slab, the cables/steel tendons are applied to replace the reinforcement. It develops a very well-organized structure to reduce material usages as well as economic span range with regard to reinforced concrete.

Post-tensioning is very useful to defeat the natural weakness of concrete in tension and to optimize its strength in compression. In concrete structures, high-tensile steel tendons/cables are placed in the element prior to casting.

If the concrete attains the preferred strength the special hydraulic jacks are used to drag tendons and retain them in tension with specially designed anchorages fixed at each end of the tendon. It offers compression at the edge of the structural member that enhances the strength of the concrete for withstanding tension stresses.

If tendons are properly curved to a specific profile, they will employ, besides compression at the perimeter, a beneficial upward set of forces (load balancing forces) that will resist applied loads, alleviating the structure from a portion of gravity effects.

In this type of slab, cables are attached in spite of reinforcement. In Steel reinforcement the gapping among bars is 4 inch to 6 inch while in Post tension slab the gapping is over 2m.

Benefits:

• It facilitates slabs and other structural members to be slimmer
• It facilitates us to develop slabs on expansive or soft soils
• The produced Cracks are retained firmly mutually
• Post tension slabs are useful for building up stronger structures economically.
• It minimizes or removes shrinkage cracking. So, no joints, or fewer joints, are essential
• It allows us to design longer spans in elevated members, like floors or beams

Drawbacks:
• Only experienced professionals can construct post tension slabs.
• If precaution is not undertaken at the time of making it, it can cause future mishaps. In various situations, untaught workers become unable fill the gaps of the tendons and wiring entirely. These gaps lead to decay of the wires which become breakable quickly and unexpected collapsing may occur.

Post Tension Slab and its benefits

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Published By
Arka Roy
http://www.constructioncost.co
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Some practical issue prior to start foundation design

In foundation design, there may occur different types of issues associated with construction and costs.

Given below, the details of main issues :-

1. The foundations should be retained as shallow as possible, suitable for coping up with climatic effect, and strength of the surface soil; particularly in waterlogged ground. Excavation in severely waterlogged ground is extravagant and time consuming.

2. Expensive and complicated shuttering details should be bypassed specifically in stiffened rafts. Proper care should be taken with buildability.

3. Curtailment in the costs of piling, betterment in ground treatment, improvements in soil mechanics, etc. have significantly impacted the economics of design, and various standard solutions becomes obsolete. So, it is very much important to evaluate construction costs and methods on a regular basis.

4. Designers should have clear ideas on the assumptions which are provided in design. These range from the inconsistencies of ground conditions, the infrequent unsuitability of refined soil analyses and the feasibility of construction.

5. The authenticity of the soil analysis, through vital evaluation.

6. Impact of construction on ground properties that range from vibration from piling, degradation of ground uncovered with excavation in unfavorable weather conditions, exclusion of overburden, seasonal disparity in the water-table, compaction of the ground by construction plant.

7. Impact of changeable shape, length and inflexibility of the foundation, and the requirement for movement and settlement joints.

8. Consequences on finished foundations of sulfate attack on concrete, ground movements because of frost heave, shrinkable clays, and the impacts of trees; also modifications in local environment due to new construction, re-orientations of heavy traffic, setting up of plant in adjacent factories inducing impact and vibration.

9. Rapid but invaluable construction is more cost-effective as compared to low-cost but slow construction to clients to bring quick return on capital investment.

10. Impact of new foundation loading on obtainable adjacent structures.

For more information, go through the following construction article civilblog.org

Some practical issue prior to start foundation design

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Published By
Arka Roy
http://www.constructioncost.co
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Some useful terms and definition used in brick masonry

Brick masonry is applied for developing buildings and other structures by bonding brick stone, stone blocks, brick blocks with various types of masonry.

For temporary sheds mud mortar is suitable but for all permanent buildings lime or cement mortars are utilized.

Different terms and definitions associated with Brick Masonry:

Course: A course refers to a layer of the same unit that runs parallel in a wall.

It is also described as a continuous row of any masonry unit like bricks concrete masonry units (CMU), stone, shingles, tiles, etc.

Bed: It belongs to the surface of stone vertical to the line of pressure. It specifies the lower surface of bricks or stones in every course.

Back: It is the inward surface of a wall that is not uncovered. The material that is used to develop the back is called backing.

Face: The outside of wall uncovered to weather is called face. The material that is utilized in the face of the wall is named as facing.

Hearting: It belongs to the inside part of a wall among n the facing and backing.

Side: It refers to the surface that builds up the boundary of bricks or stones in a transverse direction to the face and bed.

Joint: It is the meeting point of two or more bricks or stones. If the joint is parallel to the bed of bricks or stones in a course then it is termed as bed joint. Alternatively, it is a horizontal layer of mortar on which masonry units are arranged.

The joints which are set perpendicular to the bed joints are called vertical joints or side joints or just joints.

Some useful terms and definition used in brick masonry

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Published By
Arka Roy
http://www.constructioncost.co
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The process of concrete by weight and volume

atching is defined as the method for computing & combining the various components (cement, fine aggregate, coarse aggregate and water) for the formation of concrete prior to mixing following the mix design.

If this calculation is accomplished based on the volume, it is known as volume batching. Batching is categorized as follow :-

1) Volume batching
2) Weigh batching

Volume batching: In volume batching, the mass of each component is not calculated before batching, rather than there are some fabricated boxes(generally wooden) which are calculated in volume to retain the concrete components.

• This method is normally suitable for small jobs.
• Gauge boxes are applied for estimating the fine and coarse aggregate.
• The volume of gauge box has the similarity with the volume of one bag of cement.
• Gauge bow are also titled as FARMAS.
• They are formed with timbers or steel.
• Normally, they are created as deep and narrow.
• Normally, bottomless gauge boxes are not recommended for application.
• At the time of filling the gauge boxes the material should be filled loosely, no compaction is permissible.

Weigh batching: Weigh batching is the proper and most recognized method of estimating concrete ingredients. Weigh batching is performed in very vital modern concrete batching and mixing plants.

• Batching by weight is better than volume batching in terms of perfectness. Besides, it offers more consistent proportioning. It is always recommended professionally.

• It does not contain uncertainties related to bulking.
• Its equipment’s are divided into 3 general categories.
• Manual
• Semi-automatic
• Fully automatic.
• If batching is done by hand all weighing and batching of concrete are performed by hand. It is suitably for small jobs.

• For semi-automatic batching the aggregate bin gates are opened by operating switches with hand and gates are closed automatically when the material is delivered. This system also comprises of interlock that resists charging and discharging.

The process of concrete by weight and volume

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Checklist of Concrete Formwork at Construction Site throughout Concreting and Striking

Concrete formwork stands for a temporary supporting structure for concrete. It is arranged at the job site to retain the concrete in perfect position and shape unless it becomes solidified.

Ensure that formwork should be done prior to start of concreting work, throughout concreting and after elimination of formwork. Concrete formwork contains both quality and safety threats. If the formwork is improper for the concrete and work is accomplished at height, safety issue may occur.

If the formwork is imperfectly organized and does not have good resistance capacity against leak, the quality of concrete may hamper. If the concrete formwork is stored sufficiently, the cost of the project is reduced significantly.

Checklist of concrete formwork in construction site:

Formwork Checklist for Walls:

1. Make sure lateral bracings rigidly supports the forms at all points of support.
2. Layout (stop end) braced to withstand vertical and lateral loads.
3. Form panels are sufficiently braced and attached with each other.
4. Formwork corners shall be adequately attached so that leakage, bulging and spreading of concrete do not occur.
5. Make sure there is adequate length for wall ties as well as necessary strength and spacing as necessary.

6. Verify wales to maintain proper spacing and joints and they should be staggered from one tier to the next.
7. In double member wales, one member remains continuous over the location of form ties.
8. Wall ties and bolts are tightened properly.
9. In case of double member, wales are utilized and both wales should contain similar depths.

10. Verify that sufficient lap exists among forms and previously cast concrete.
11. Make sure that there is no grout leakage at joints among panels and joints connecting old concrete and panels over them.
12. Examine the provision of resistance against uplift for sloping faces of concrete formwork.

13. Make sure that the installation of wall forms and placement of concrete should be done at the construction site in the presence of an experienced supervisor.

To get more details, go through the following construction article dssekamatte.blogspot.in

Checklist of Concrete Formwork at Construction Site throughout Concreting and Striking

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Published By
Arka Roy
http://www.constructioncost.co
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AStrutTie 2017 – The powerful software for structural design

HanGil IT develops AStrutTie 2017, a software that can be used for strut-tie model analysis and design for concrete members having disturbed stress region(s).

This software facilitates the construction professionals to design corbel (bracket), abutment/pier footing, bridge pier coping (pier cap), frame corner, anchorage zone, deep beam, etc. The software is compatible with U.S (ACI 318, AASHTO LRFD) and Europe (EuroCode 2) codes and specifications.

A concrete member is segregated into B-region(s) and D-region(s). D-regions stand for the portions of structure where the strain distribution is extremely nonlinear. Empirical approaches are followed for most design practices for D-regions.

The strut-tie model is suitable to understand load transfer mechanisms and structural behavior in an efficient manner and it enhance the capability of the designers to deal with unconventional circumstances along with D-regions.

The most accurate strut-tie models is developed based on the principal stress flows and/or evolutionary structural optimization (ESO) results. A specialized solver is connected that has the ability to deal with any types of internally/externally (in)determinate strut-tie models. The strut-tie model provisions of ACI 318-14 (2014), AASHTO LRFD (2014), and EC2 (2004) are employed.

In order to design the strut-tie model rapidly and easily, multirole templates are arranged for corbel (bracket), abutment footing, pier footing, bridge pier coping (pier cap), frame corner, anchorage zones together with inclined and straight tendons, and deep beams with concentrated and distributed loads.

The shapes of concrete members and truss models are also formed by importing .dxf files. Advanced element sets illustrate truss mechanism, truss and arch mechanism, and fan action is arranged.

AStrutTie offers several automated design checks concerning the conditions for rebar requirement and strength verification of struts and nodal zones.

Visual verifications of strength conditions can also be performed. A structural design report is created automatically, and design results are evaluated by previewing the report. The structural design report is printed as a .rtf or .xlsx file format.

To download the software, click on the following link http://astruttie.aroad.co.kr

AStrutTie 2017 – The powerful software for structural design

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Published By
Arka Roy
http://www.constructioncost.co
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Definition of mortar and it’s different types

Mortar is a useful construction material combined with cement, lime, fine aggregates (sand, surkhi), water and various types of admixtures. It is utilized in masonry construction to bind the masonry or structural units as well as fill & seal the spaces among the stone, bricks and cement blocks applied in construction. It comes in the form of a paste and sets solid.

Often decorative colors are included for the architectural purpose. When the mortar in exact ratios of two or more components is available in premix mortar form, it is known as ready mix mortar.

The purpose of ready mix mortar is to unite building materials, to accomplish pointing work and plaster work, develop an flat and soft bedding layers, develop joints of pipe, conceal the open joints of brickwork and stone, accomplish structure maintenance work etc.

Given below, the details of various types of ready mix mortar accessible in the market on the basis of their functionality and mixture of binding material.

01. Ready mix cement mortar
02. Ready mix lime mortar
03. Ready mix surkhi mortar
04. Ready mix cement lime mortar

Ready mix Cement mortar is admixture of cement and sand, where cement functions as a binding material. The ratio of cement to sand fluctuates from 1:2 to 1:6 on the basis of their strength necessary for a specific work.

Ready mix Lime Mortar is premix of lime and sand, where lime functions as a binding material. The proportion of lime to sand ratio is maintained as 1:2(1 part of dry lime is combined with 2 part of dry sand).

Ready mix Surkhi Mortar is premix of lime, surkhi and water. Lime to surkhi ratio is kept 1:2 (1 part of dry lime is mix with 2 part of dry surkhi). It is type of lime mortar where sand is replaced by surkhi for saving and potency. Surkhi stands for finely burnt clay particles and normally formed with slightly under burnt bricks. Good surkhi should be rinsed properly and does not contain any admixture of foreign substances.

Ready mix Cement Lime Mortar is premix of Cement, lime and sand, where cement and lime function as binding materials. It is recognized as combination or gauge ready mix mortar. The formation of cement to lime mortar by volume is approximately 1:6 to 1:9. This type of mortar combination (i.e. lime and cement) is considered as tough, solid and cost-effective.

Ready mix mortar is obtainable in 5 kg (For Repairing), 25 kg and 50kg bags. Water should have been added on the construction site following specific work requirement.

Adding water in premix on the construction site should be done on the basis of IS Code or as suggested by an engineer in charge. In recent times, special mortar is utilized for the repair and maintenance purpose which contain properties like the free flow and high strength with regard to the normal mortar.

Based on their function, better shelf life and strength, several brands are found in the market with cost of Rs150to Rs700 per 50 kg bag of ready mix Mortar.

Definition of mortar and it’s different types

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Published By
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http://www.constructioncost.co
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How to estimate cement bags in 1 cubic meter

Suppose the proportion of nominal mix is 1:2:4 (one part cement, 2 part sand and 4 part aggregate)

Wastage of cement is taken as 2%
Output of mix is provided as 67%.

For 1 cum output, the requirement of dry mix is 1/0.67 = 1.49 say 1.50 cum.
After including the wastage (2%), the output will be (1.50 + 0.02) = 1.52 cum.
Volume of cement = (cement/cement+sand+aggregate) × Total material

= (1/1+2+4) × 1.52
=0.2171 cum
The density of cement is 1440 kg/cum and
Weight of 1 bag cement = 50 kg.

So, volume of 1 bag cement = 50/1440
=0.0347 cum.
No. of cement bags essential in 1 cubic meter = 0.2171/0.0347
= 6.25 bags.
The above formula can be utilized for measuring cement for other nominal mixes.

To get more details, watch the following video tutorial.

How to estimate cement bags in 1 cubic meter

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Arka Roy
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Units of measurement used in surveying & construction works

Unit of measurement is also known as the International System of Units, or SI. Units of measure in the metric system. The units of length or linear size are derived from the metre. They comprise of the kilometre (km) that is 1000 meters, the centimetre (cm), and the millimetre (mm) which is 1/1000th of a meter.

A unit of measurement refers to a specific magnitude of a quantity, described and approved by convention or by law, that is used as a standard for measurement of the same kind of quantity.

Any other quantity of that type can be stated as a multiple of the unit of measurement. As for instance, a length is a physical quantity.

Standard unit of measurement :-

Type – U.S. Unit – Metric Unit
Length – Inches, Feet, Yards, Miles – Millimeters, Centimeters, Meters, Kilometers
Weight – Ounces, Pounds – Grams, Kilograms
Time – Seconds, Minutes, Hours – Seconds, Minutes, Hours
Volume – Ounces, Gallons – Milliliters, Liters

Given below, the details of measurements which are utilized in surveying and construction works :-

For construction work: feet, inches, fractions of inches (m, mm)
For most surveys: feet, tenths, hundredths, thousandths (m, mm)

For National Geodetic Survey (NGS) control surveys: meters, 0.1, 0.01, 0.001 m

The following equivalents are used frequently :-
1 meter=39.37 in =3.2808 ft
1 rod =1 pole=1 perch=16.5ft(5.029 m)
1 engineer’s chain =100 ft =100 links (30.48 m)
1 Gunter’s chain= 66 ft (20.11 m) =100

Gunter’s links(lk)=4 rods=0.020 km
1 acre=100,000 sq (Gunter’s) links=43,560ft2 = 160 rods2 =10 sq (Gunter’s) chains=4046.87m2 = 0.4047 ha
1 rood=1011.5 m2 =40 rods2
1 ha= 10,000 m2 =107,639.10 ft2 = 2.471 acres
1 arpent=about 0.85 acre, or length of side of 1 square arpent (varies) (about 3439.1 m2)

1 statute mi=5280 ft=1609.35 m
1 mi2 = 640 acres (258.94 ha)
1 nautical mi (U.S.)= 6080.27 ft= 1853.248 m
1 fathom=6 ft (1.829 m)
1 cubit=18 in (0.457 m)
1 degree=0.01745 rad=60 min =3600 s
sin 1 =0.01745241
1 rad = 57.30 degree

For more information, go through the following link www.onlinecivilforum.com

Units of measurement used in surveying & construction works

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Published By
Arka Roy
http://www.constructioncost.co
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