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Tuesday, 10 April 2018

A BRIEF HISTORY OF STRUCTURAL ARCHITECTURE

More than any other engineering discipline, Architecture/Mechanics/Structures is the proud outcome of a of a long and distinguished history. Our profession, second oldest, would be better appreciated if we were to develop a sense of our evolution.

1.1 Before the Greeks

2. Throughout antiquity, structural engineering existing as an art rather than a science. No record exists of any rational consideration, either as to the strength of structural members or as to the behavior of structural materials. The builders were guided by rules of thumbs and experience, which were passed from generation to generation, guarded by secrets of the guild, and seldom supplemented by new knowledge. Despite this, structures erected before Galileo are by modern standards quite phenomenal (pyramids, Via Appia, aqueducs, Colisseums, Gothic cathedrals to name a few).

3. The first structural engineer in history seems to have been Imhotep, one of only two commoners to be deified. He was the builder of the step pyramid of Sakkara about 3,000 B.C., and yielded great influence over ancient Egypt.

4. Hamurrabi’s code in Babylonia (1750 BC) included among its 282 laws penalties for those “architects” whose houses collapsed, Fig. 1.1.

1.2 Greeks
5 The greek philosopher Pythagoras (born around 582 B.C.) founded his famous school, which was primarily a secret religious society, at Crotona in southern Italy. At his school he allowed.

Archimed conqueror of Syracuse. 1.3 Romans 10 Science made much less progress under the Romans than under the apparently were more practical, and were not as interested in abstract thinking though they were excellent fighters and builders. 11 As the roman empire expanded, the Romans built great roads (some of them still in use) such as the Via Appia, Cassia, Aurelia; Also they built great bridges (such as the third of a mile bridge over the Rhine built by Caesars), and stadium (Colliseum). 12 One of the most notable Roman construction was the Pantheon,

CONSTRUCTION VOCABULARY

Air return: A series of ducts in air conditioning system to return used air to the air handler to be reconditioned.

Anchor Bolts: (also called J-bolts) Bolts embedded in concrete foundation used to hold sills in place.

Anchor Straps: Straps embedded in concrete foundation used to hold sills in place, most commonly MASAs in our houses.

Apron: A piece of the driveway between sidewalk and curb.

Back Fill: The replacement of dirt in holes, trenches and around foundations.

Backing (aka blocking) a non-structural (usually 2x) framed support (i.e. for drywall).

Balloon Framing: A special situationally required type of construction with studs that are longer than the standard length..

Bay: The space between two parallel framing members (i.e. trusses).

Beam: A horizontal structural member running between posts, columns or walls.

Bearing wall (aka partition): A wall which carries a vertical structural load in addition to its own weight.

Bevel: To cut an angle other than a right angle, such as on the edge of a board. Bird block (aka frieze board):An attic vent located between truss tails.

Bird’s Mouth: A notch cut in the underside of a rafter to fit the top plate.

Blocking (aka backing): A non-structural 2x framing support (i.e. for drywall)

Board: Lumber less than 2” thick.

Board Foot: The equivalent of a board 1’ square and 1” thick.

Box Header: A horizontal structural member over an opening having a rectangular cross-section with a hole in the middle, which we fill with insulation.

Building Code: A collection of rules and regulations for construction established by organizations based on experience and experiment, and enacted and enforced by local municipalities. California corner: A framing member used at the intersection of two walls, consisting of three studs nailed together to form a U-shaped cross-section.

Camber: The slight arch in a beam or truss which prevents it from bending into a downward shape under normal load.

Cantilevered: Extending horizontally beyond support.

Cant Strip: A triangular shaped strip used under the edges of roofing by walls on flat roofs.

Cased Opening: An interior opening without a door that is finished with jamb and trim. Caulking: A flexible material used to seal a gap in a joint

For All words Click Here

Definitions of Civil Engineering Terms Part-1 Prepared by TALAL AHMED KAMAL

ABRASION: The process of wearing away by friction.

ABUTMENT: A concrete support wall constructed at both ends of a bridge or an arch, in order to resist the horizontal force from the bridge or the arch, support the ends of the bridge span and to prevent the bank from sliding under.

ACCELERATOR: A substance such as calcium chloride (CaCl2), added in small quantities (max. 0.03% of the cement) to plain concrete to hasten its hardening rate, its set or both.

ACQUISITION: The process of obtaining Right-of-Way.

ACTIVE EARTH PRESSURE: The horizontal push from earth onto a wall. The active earth force from sand on to a free retaining wall is equivalent to that from a fluid of density 0.25 to 0.30 times that of the sand. The force from sand on to a fixed retaining wall is very much more.

ADDENDUM OR ADDENDA: Written instruments or documents issued prior to the execution of a contract to modify or revise the bidding documents.

ADHESION OR BOND: The sticking together of structural parts by mechanical or chemical bonding using a cement or glue.

Monday, 9 April 2018

What are the functions of different components of a typical expansion joint?

 In a typical expansion joint, it normally contains the following components: joint sealant, joint filler, dowel bar, PVC dowel sleeve, bond breaker tape and cradle bent. Joint sealant: it seals the joint width and prevents water and dirt from entering the joint and causing dowel bar corrosion and unexpected joint stress resulting from restrained movement. Joint filler: it is compressible so that the joint can expand freely without constraint. Someone may doubt that even without its presence, the joint can still expand freely. In fact, its presence is necessary because it serves the purpose of space occupation such that even if dirt and rubbish are intruded in the joint, there is no space left for their accommodation. Dowel bar: This is a major component of the joint. It serves to guide the direction of movement of concrete expansion. Therefore, the incorrect direction of placement of dowel bar will induce stresses in the joint during thermal expansion. On the other hand, it links the two adjacent structures by transferring loads across the joints. PVC dowel sleeve: It serves to facilitate the movement of dowel bar. On one side of the joint, the dowel bar is encased in concrete. On the other side, however, the PVC dowel sleeve is bonded directly to concrete so that movement of dowel bar can take place. One may notice that the detailing of normal expansion joints in Highways Standard Drawing is in such a way that part of PVC dowel sleeve is also extended to the other part of the joint where the dowel bar has directly adhered to concrete. In this case, it appears that this arrangement prevents the movement of joint. If this is the case, why should designers purposely put up such arrangement? In fact, the rationale behind this is to avoid water from getting into contact with dowel bar in case the joint sealant fails. As PVC is a flexible material, it only minutely hinders the movement of joint only under this design.

Bond breaker tape: As the majority of joint sealant is applied in liquid form during construction, the bond breaker tape helps to prevent flowing of sealant liquid inside the joint. Cradle bar: It helps to uphold the dowel bar in position during construction.

Problem 1: Design a plain concrete footing for a column of 400 mm x 400 mm carrying an axial load of 400 kN under service loads. Assume safe bearing capacity of soil as 300 kN/m2 at a depth of 1 m below the ground level. Use M 20 and Fe 415 for the design.

Solution 1:
Plain concrete footing is given in secs.11.28.2(A)1 and 11.28.5(b).

Step 1: Transfer of axial force at the base of column
It is essential that the total factored loads must be transferred at the base of column without any reinforcement. For that the bearing resistance should be greater than the total factored load Pu.
Here, the factored load Pu = 400(1.5) = 600 kN.

The bearing stress, as per cl.34.4 of IS 456 and given in Eqs.11.7 and 8 of sec.11.28.5(g) of Lesson 28, is brσ = 0.45 fck (A1/A2)1/2 (11.7)
with a condition that
(A1/A2)1/2 ≤ 2.0 (11.8)
Since the bearing stress brσ at the column-footing interface will be governed by the column face, we have A1 = A2 = 400(400) = 160000 mm2. Using A1 = A2, in Eq.11.7, we have

Pbr = Bearing force = 0.45 fck A1 = 0.45(20)(160000)(10-3) = 1440 kN > Pu (= 600 kN).
Thus, the full transfer of load Pu is possible without any reinforcement.

Sunday, 8 April 2018

Design a isolated footing for a column of 400mm*400mm subjected to an axial load of 1800KN. The safe bearing capacity of foundation soil is 150KN/MM.

ANS:-
Given Data
1.Size of column:- 400mm*400mm
2. Given load (p) :- 1800KN
3. SBC :- 150KN/mm
4. Assume m20 grade of concrete. And Fe 415 grade of
Steel.     
 STEP 1:-
Area of footing
Increase 10% of given load
Area of footing :- 10% of p+p /SBC
                             10*1800+1800 /100
                             1980 / 150
                              13.2mm
As we design square footing then,
                           A2 = 13.2
                           a = 3.63 =4m
Hence, provide 4*4mfooting size

How to Use Railing,wall and foliage command in 3ds-Max (Session-10)