Static indeterminacy

#Structural Analysis:

Static indeterminacy

(A) Pin Jointed or Truss

(B) Rigid jointed or Frames

(C) Beam

..................

Center of pressure & Position of Center of pressure

 #Fluid mechanics (Hydraulics):

• दबाव का केंद्र क्या है?
 उत्तर :समतल सतह पर दबाव का केंद्र वह  बिंदु होता है जिस पर परिणामी बल कार्य कर रहा होता है |

•What is center of pressure ?
 Answer : 

In plane surface the centre of pressure is the point of application on which the resultant force is acting.

The center of pressure is the point where the total sum of a pressure field acts on a body, causing a force to act through that point. The total force vector acting at the center of pressure is the value of the integrated vectorial pressure field. The resultant force and center of pressure location produce equivalent force and moment on the body as the original pressure field. Pressure fields occur in both static and dynamic fluid mechanics. Specification of the center of pressure, the reference point from which the center of pressure is referenced, and the associated force vector allows the moment generated about any point to be computed by a translation from the reference point to the desired new point. It is common for the center of pressure to be located on the body, but in fluid flows it is possible for the pressure field to exert a moment on the body of such magnitude that the center of pressure is located outside the body

Centre of Pressure depth

The centre of pressure for certain bodies are: 

(a) Rectangular with face coinciding with free surface

(b) Triangle with base at the free surface


(c) Triangle with apex at free surface

(d) Circle touching free surface

Question : The position of center of pressure on a plane surface immersed vertically in a static mass of fluid is

A. at the centroid of the submerged area

B. always above the centroid of the area

C. always below the centroid of the area

D. none of the above

Answer: Option C

Efflorescence (full explanation )

 #Efflorescence:-

एफ्लोरेसेंस नमक का एक क्रिस्टलीय जमा होता है जो ईंट, कंक्रीट, पत्थर, प्लास्टर या अन्य भवन सतहों पर या पानी मौजूद होने पर बन सकता है।  इसमें एक सफेद या भूरा रंग होता है और इसमें नमक जमा होता है जो पानी के वाष्पीकरण के बाद सतह पर रहता है।

👇

If you want to join contact us through leaving comment on the comment section .

Efflorescence:-

Efflorescence is a crystalline deposit, usually white, that maydevelop on the surfaces of masonry construction (see Fig. 1).Often it appears just after the structure is completed—when builder, architect, and owner are most concerned with the appearance of the new structure. Although unattractive, efflorescence isgenerally harmless. However, some forms (alkali carbonates) maybe able to saponify paints, leading to failure of the paint-masonry bond. Other deposits can occur within the surface pores of thematerial, causing expansion that may disrupt the surface. This condition is sometimes termed cryptoflorescence.This information sheet examines the causes, prevention, andremoval of efflorescence encountered on masonry surfaces.

Formation of white patches on the surface of bricks due to the presence of insoluble salts in the clay used for making bricks.

👇

The presence of efflorescence, if any, is classified as under:

 (a) No efflorescence: If the deposit of efflorescence is imperceptible. 

(b) Slight efflorescence: When the efflorescence doesnot cover 10% of the exposed area of the brick. efflorescence is more than 10% but less than 50% of the exposed area and the deposit does not

(c) Moderate efflorescence : When thepowder or flake the surface. 

(d) Heavy efflorescence: When the efflorescence covers 50% or more area but the deposit does not or flake the surface.powder 

(e) Serious efflorescence: When the deposit of efflorescence salts is heavy and is accompanied bypowdering and/or flaking of the exposed surfaces.

(ईंटों को बनाने के लिए उपयोग की जाने वाली मिट्टी में अघुलनशील लवणों की उपस्थिति के कारण ईंटों की सतह पर सफेद धब्बे बनना।) 👇

https://youtu.be/aVRFOe5ri3w

Causes

A combination of three common circumstances causes efflorescence:

• soluble compounds in the masonry or adjoining materials

• moisture to pick up the compounds and carry them to the surface

• evaporation or hydrostatic pressure that causes the solution to move

Prevention

Since many factors influence the formation of efflorescence, it is difficult to predict if and when any will appear: There is no accepted standard test method for measuringtheefflorescencepotential of masonry mortar. Several experimental methods havebeen proposed, but none has been accepted as effectively predicting the performance of mortar materials in actual use.

ASTM C 67 does include an efflorescence test for clay brick. 

The test is helpful in indicating whether or not clay units will 

effloresce by themselves when exposed to moisture. However, 

it does not address the potential for efflorescence resulting fromcement-brick reactions or other external conditions that oftenoccur in service.

Given the characteristics of masonry materials and construc-tion, it is virtually impossible to eliminate all the soluble salts, construct walls containing no free moisture, or completely eliminate paths of moisture migration. However, steps can betaken to minimize the extent of these three contributing factors.

Good workmanship is one of the most effective means of limiting

the potential for efflorescence.

Most efflorescence can be classified as temporary. Often termed

"new building bloom," indicating its link to the exposure 

conditions and excess moisture that accompany new masonry 

construction, it is harmless and should not cause undue concern.

On the other hand, recurrent efflorescence indicates a chronic

moisture problem. Efforts should be taken to correct the moisture

problem, thereby preventing and eliminating recurrent efflorescence. 

The following recommendations are targetedtoward that goal:

Provide for good drainage

— Correctly install waterstops, flashing, weepholes, and cop-

ings per design details. Maintain clean cavities and unob-

structed weepholes during the construction of cavity walls.

Construct good mortar joints

— Tool all mortar joints with a V- or concave-shaped jointer to

compact the mortar at the exposed surface and create a tight

bond between mortar and masonry unit Weeping, raked, and untooled struck joints are not recommended in exposed applications.

— Assure that joints are properly filled. Deteriorated or defec-tive mortar joints should be repointed to keep moisture outof the wall.

Ensure proper curing

— Assure adequate hydration of cementitious materials by 

protecting masonry from cold temperatures, premature 

drying, or improper use of admixtures.

Limit water entry

— Apply paint or other proven protective treatment to the 

outside surfaces of porous masonry units. Caulk around 

window and door openings. Seal or otherwise repair cracked

joints in walls. Also, use through-wall flashing at ground level to prevent capillary rise of ground moisture.

— Install vapor barriers in exterior walls (interior surfaces of

exterior walls) or apply vaporproof paint to interior surfaces

and use designs that minimize condensation within masonry.

— Carefully plan the installation of lawn sprinklers or any 

other water source so that walls are not subjected to unnecessary wetting.

— If feasible, use wide overhanging roofs to protect walls from rainfall.

Removal

Since efflorescence often occurs during or right after construction,the first impulse is to immediately wash it off with water or 
a masonry cleaning solution. This is not advisable, particularly in cool or cold damp weather, when the RemovalSince efflorescence often occurs during or right after construction,the first impulse is to immediately wash it off with water or a masonry cleaning solution. This is not advisable, particularly in cool or cold damp weather, when the primary result of suchaction will be to introduce more water into the masonry wall.
Given time, efflorescence will often disappear by itself or at mostmay require mild cleaning measures such as dry brushing or rinsing and brushing with a stiff brush. If this does not producesatisfactory results, it may be necessary to wash the surface witha proprietary masonry cleaning solution or a very dilute solutionof muriatic acid (1% to 10%). In any case, prior to removingefflorescence from a surface, the surest way to establish an appropriate cleaning procedure is to chemically identify thedeposit (see table on next page). Following cleaning, the wallshould be thoroughly rinsed with clean water to remove all traces of the cleaner Prior to using a proprietary cleaneror muriatic acidsolution, the cleaning agent’s
compatibilty with the masonry unitsshould be verified with the manufacturer of the units.Where integrallycolored concretemasonry units or mortars areinvolved, use only a 1% to 2% acid solution or a proprietarycleaner specificallyrecommended for that application. In any event, careshould be taken tprimary result of such action will be to introduce more water into the masonry wall.

Removing Some Forms of Efflorescence

Common compound Recommended cleaning method

Alkali sulfate Stiff brush. If necessary, brush with water.

Calcium sulfate Stiff brush. If chronic, add water washing.

Calcium carbonate Stiff brush if not adherent. 

If adherent, apply dilute acid or proprietary cleaning 

solution to dissolve efflorescence.

R.C.C और P.C.C क्या है ? What is R.C.C and P.C.C ?

 #R.C.C और P.C.C  क्या है ? What is R.C.C and P.C.C ?

Answer :-

(1)R.C.C :-

In Hindi :-R.C.C (आर.सी.सी) का पूरा नाम (पूर्ण रूप) " प्रबलित सिमेंट कंक्रीट " है । सीमेंट, मोटा मिलावा (coarse aggregate), बारीक मिलावा (fine aggregate) और पानी से बने मिश्रण 'कंक्रीट' में जब इस्पात की छड़ों को दबाकर सिविल इंजीनियरिंग के किसी अवयवcomponent) की संरचना की जाती है तो वह प्रबलित सीमेट कंक्रीट या आर. सी. सी. (reinforced cement concrete) कहलाती है।

कंक्रीट की संपीडन सामर्थ्य (compressive strength), इसकी तनन सामर्थ्य (tensile strength) की तुलना में बहुत अधिक होती है। कंक्रीट की संपीडन सामर्थ्य 15 N/mm^2  होती है जो डिजाइन के लिए केवल 5 N/mm^2  ली जाती है । कंक्रीट की तनन सामर्थ्य कंक्रीट की तुलना में 10 से 15% ही होती है, परंतु कक्रीट की तनन क्षमता शून्य मानते हैं। अतः स्पष्ट है कि प्रबलित सीमेन्ट कक्रीट में सीमेंट कंक्रीट तो केवल संपीडन (compression) ही वहन करती है, जबकि तनाव इस्पात द्वारा वहन किया जाता है। अर्थात् प्रबलन का प्रायोजन केवल तनाव वहन करना होता है ।

IN English :-Full form of RCC is "Reinforced Cement Concert "

Reinforced concrete (RC), also called reinforced cement concrete (RCC), 

 RCC is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars (rebar) and is usually embedded passively in the concrete before the concrete sets. Worldwide, in volume terms it is an absolutely key engineering material.

What is properties of good RCC?

1. It should be capable of resisting expected tensile, compressive, bending and shear forces.

2. It should not show excessive deflection and spoil serviceability requirement.

3. There should be proper cover to the reinforcement, so that the corrossion is prevented.

4. The hair cracks developed should be within the permissible limit.

5. It is a good fire resistant material.

6. When it is fresh, it can be moulded to any desired shape and size.

7. Durability is very good.

8. RCC structure can be designed to take any load.

Uses of RCC ( reinforced cement concrete)

RCC is a widely used as building material in construction of all structural member of Industrial and residential building part like footing, column, beam and slab and also some of others structure like building of bridge, dams, water tanks, stairs, bunkers etc.

Some of its important uses of rcc are listed below:

1) rcc is used as a structural element, the common structural elements in a building where rcc is used are:

(a) Footings (b) Columns

(c) Beams and lintels (d) Chejjas, roofs and slabs.

(e) Stairs.

2) RCC is used for the construction of storage structures like

(a) Water tanks (b) Dams

(c) Bins (d) Silos and bunkers.

3) RCC is used for the construction of big structures like

(a) Bridges (b) Retaining walls

(c) Docks and harbours (d) Under water structures.

4) rcc is used for pre-casting

(a) Railway sleepers (b) Electric poles

5) RCC is used for constructing tall structures like

(a) Multistorey buildings (b) Chimneys

(c) Towers.

6) rcc is used for paving

(a) Roads (b) Airports.

7) rcc is used in building atomic plants to prevent danger of radiation. For this purpose rcc wall built are 1.5 m to 2.0 Thick.

• Watch this video it is very  use full  for RCC concept .

(2) P.C.C:-

In Hindi :- P.C.C (पी.सी.सी) जिसे हिंदी में सादा सीमेंट कंक्रीट कहते है। रेत, एग्रीगेट (कपची), और पानी के मिश्रण से बने कंक्रीट को प्लेन सीमेंट कंक्रीट कहते है। इसे सीमेंट कंक्रीट भी कहते । इसमे स्पात (Steel) नही डाली जाती ।

In English :-Plain cement concrete is the mixture of cement, fine aggregate(sand) and coarse aggregate without steel. PCC is an important component of a building which is laid on the soil surface to avoid direct contact of reinforcement of concrete with soil and water.

 

#Uses of Plain Cement Concrete 

Plain cement concrete is generally used for the foundation. However, its other uses are:

Other Uses of Plain Cement Concrete are listed below:

As bed concrete below the wall footings, column footings and on walls below beams.

As sill concrete to get a hard and even surface at window and ventilator sills.

As to coping concrete over the parapet and compound walls.

For flagging the area around the buildings.

To make pavements.

To make tennis courts, basketball courts etc.

Plinth Protection

Storm/ Sewer at drains, small retaining walls.

Limitations:-

Do not mix the materials on bare land.

Do not just-pour the water in materials by means of a pipe. i.e. without any measurement control.

Do not allow the PCC without formwork.

Do not pour concrete without levelling and compacting.

Do not pour concrete in the pit from a height of more than 1.5 m.

Do not allow extra cement mortar on top of PCC. for smooth finishing.

                                    ________