Ultimate load , working load and ultimate load, 3. In a reinforced T beam the position of neutral axis, 3. CO417.3 CO417.3 Q4 Derive Expression for position of Neutral axis and Moment of Resistance of a balanced rectangular section. Example 17.11 Find the moment of resistance of a singly reinforced beam section 225 mm wide and 350 mm deep to the centre of the tensile reinforcement if the permissible stresses in concrete and steel are 230 N/mm 2 and 7N/mm 2. Find the moment … At ultimate moment of resistance, factored bending moment = resisting moment. When the tendon of a rectangular prestressed beam of cross sectional area A is subjected to a load W through the centroidal longitudinal axis of beam, ( where M= maximum bending moment and ,Z = section modulus) then the maximum stress in the beam section will be. Effective prestressing force is P and the span l.What is the equivalent upward acting uniform load? Both. 262. Over Reinforced Section. At this section, A combined footing for two columns should be designed for, In a combined footing, the reinforcement should be placed, A combined trapezoidal footing for two columns becomes essential when, The precast concrete piles are generally used for a maximum design load of about except for large prestressed piles, The hammer used in driving piles should be, In designing reinforced concrete piles as a column, it is considered as, The length of a reinforced concrete pile is taken as……..the length embedded in firm stratum. Steel reinforcing is located near the bottom of the beam, which is the tension side. For most practical designs, ACI specifies the value of φ as 0.9; however, special cases exist for which lower values apply. As per This is primarily due to curvature at the support being, 287. 332. Criterion. 0.375 times the area of steel provided at in the shorter span, 284. While the compressions carried by the concrete. The high carbon content in the steel causes, 260. 267. Concrete is brittle and it fails by crushing suddenly. bars at a support in a simply supported beam is to resist in that zone. Adjacent spans are unloaded and next spans are loaded. Sorry, you do not have permission to ask a question, You must login to ask question. (ii) Define and explain Balanced Section I (iii) Explain the meaning of a Under-Reinforced Section, (iv) Is Moment of Resistance of an over-reinforced section … Minimum p-itch of transverse reinforcement in a •Find cross section of concrete and area of steel required for a simply supported rectangular beam •Span = 15ft •Dead Load = 1.27 kips/ft •Live Load = 2.15 kips/ft •f’c = 4000 psi •fy = 60,000 psi The Every singly reinforced beam should be designed as under-reinforced sections because this section gives enough warning before failure. 330. Top ring beam of an Intze tank carries a hoop tension of 120 KN . From limiting deflection point of view , use of high strength steel in RC beam result in, 278. In a pedestal, the factor by which the effective length should not exceed the least lateral dimension is. 252. They are as follows: Method 1 – Elastic theory; Method 2 – Steel beam theory; Method 1. The magnitude of loss of pre-stress due to relaxation of steel should be taken to vary from………of the average initial stress. Ductile. Given a reinforced concrete beam with the size of bxh = 200mmx450mm, the strength grade of concrete is C30, four 16-mm-diameter HRB400 reinforcing bars are embedded (As=804mm²), the environment category is … Ultimate load, ultimate loadand working load, 3. (c) a pile foundation is used where the top soil is relatively weak. –and the slab thickness is. Span next to the adjacent spans of the support plus alternate spans (Ans), 279. I Hence moment of resistance SAQ 4 I (i) How many types of singly reinforced sections can be had based on percentage of rei~forcement provided? The intensity of compressive stress just, above the neutral axis, is of very………………magnitude. Deck bridges have the main disadvantages that, 3. Resistance moment at any section must be at least 70% of moment at that section obtained by … In the Singly reinforced beam, the ultimate bending moment and the tension due to bending are carried by the reinforcement. i think we have no need to calculations, but go through the simple logic that.. bending in concrete in N/mm2. (c) the cost of supporting structure and foundation is reduced, (a) high strength concrete should be used, (b) low strength concrete should be used, (c) high strength concrete and low tensile steel should be used, (d) high strength concrete and high tensile steel should be used (Ans), (a) force and moment equilibrium equations (Ans), (b) stress-strain relationship of concrete and steel, (c) moment equilibrium and compatibility condition, (a) a plane cross-section before loading remain plane after loading, (b) any change in loading produces change of stress in concrete, (c) pre-stressing in steel remains constant, (a) placed at the centre of cross-setion over the entire span, (b) placed at some eccentricity over the entire span, (c) varying linearly from the centre of cross-section of the ends to maximum eccentricity at the middle section, (d) parabolic with zero eccentricity at the ends and maximum eccentricity at the centre of the span (Ans), (b) only longitudinal stresses exist (Ans), (d) shape of the cross-section of beam (Ans), (b) shrinkage and creep of concrete (Ans), (c) elastic deformation of concrete when wires are tensioned successively, (a) a straight profile along the centroidal axis, (b) a straight profile along with the lower kern, (c) a parabolic profile with convexity downward (Ans), (d) a circular profile with convexity upward, (c) either single stage or multi stage process depending upon the magnitude of load transfer, (d) the same manner as in post-tensioning scheme, (a) 60% of the ultimate tensile strength of the bar for steels without a definite yield point, (b) 80% of the yield stress for steels with guaranteed yield point, (c) 80% of the ultimate strength of the bar for steel without a definite yield point (Ans), (d) the yield stress for steel with guaranteed yield point (Ans), (c) modulus of elasticity and creep values are higher, (d) high modulus of elasticity and low creep (Ans), 238. A pre-stressed concrete induces artificially……….stresses in a structure before it is loaded. Moment of resistance of reinforced concrete beams are calculated based on following assumptions: 1. For structural frames over four stories high providing lateral stability, the redistribution of moments should not exceed 10%. (a) when the members are subjected to alternate external loads and the bending moment in the sections reverses, (b) when the members are subjected to loading eccentric on either side of the axis, (c) when the members are subjected to accidental lateral loads, (b) compressive steel is under – stressed, (c) tensile steel required is more than that for balanced section, (d) concrete is not stressed to its full value, (a) compression steel resists the compression, (b) stress in compression steel is equal to stress in tension steel, (c) in tension and compression concrete, no stress in developed, (a) one – third of the effective span of the T – beam, ( b) twelve times the depth of slab plus breadth of rib, (a)total thickness of the slab, including cover, (b) width of the portion of the beam in the compression zone, (c) width of the portion of the beam in the tensile zone (Ans), (c) accommodate the tensile reinforcement with proper spacing between the bases (Ans), (c) 0.2 % to 0.3 % of the web area depending upon the breadth of the slab, (a) centre of the flange and the top of the tensile reinforcement, (b) top of the flange and the centre of the tensile reinforcement (Ans), (c) bottom of the flange and the centre of the tensile reinforcement, (d) centre of the flange and the bottom of the tensile reinforcement, (c) depend on the thickness of flange in relation to total depth and percentage of reinforcement (Ans), 132.When the slab is supported on all the four edges and the ratio of long span to short span is small, bending takes place along both the spans. In many cases, it is more convenient to express the moment strength of a singly reinforced section in terms of the nondimensional steel ratio, ρ, defined as. but if the section is in under reinforced, we will get such kind of warnings. 3. Take D' As 50 Mm. The probability of failure implied in limit state design is of the order of, 310. Moment of resistance of reinforced concrete beams are calculated based on following assumptions: 6.The joint action of steel and concrete, in a reinforced concrete section, depends upon the, (b) absence of corrosion of steel bars embedded in the concrete, (c) practically equal thermal expansion of both concrete and steel, (a) at any cross-section, plane sections before bending remain plane after bending, (b) all tensile stresses are taken up by reinforcement alone and none by the concrete, (c) steel reinforcement is free from initial stresses when it is embedded in concrete, (c) both concrete and steel will resist tension (Ans), (d) both concrete and steel will resist compression, (a) Young’s modulus of steel to the young’s modulus of concrete (Ans), (b) young’s modulus of concrete to the young’s modulus of steel, (c) load carried by steel to the load carried by concrete (Ans), (d) load carried by concrete to the load carried by steel, 16.In a singly reinforced concrete beam, as the load increases, (b) only steel bars will resist tension (Ans), (c) both concrete and steel will resist tension, 18.Normally the tensile strength of concrete is about……..of its compressive strength, 21.A reinforced concrete beam will crack if tensile stress set up in the concrete below the neutral axis is, (b) more than the permissible stress (Ans), (a) distribute the effect of point load on the slab more evenly and uniformly, (b) distribute the shrinkage and temperature cracks more evenly, (c) keep the main reinforcement in position, 23.The analysis of slab spanning of one dimension is done by assuming it to be a beam of, (a) compressive force developed in concrete, (b) tensile force developed in steel (Ans), (a) steel reinforcement is not fully stressed to its permissible value (Ans), (b) concrete is not fully stressed to its permissible value, (a) the lever arm will be less than that for a balanced section, (b) the maximum stress developed by steel will be equal to the allowable stress in steel, (c) the maximum stress developed by concrete will be equal to allowable stress in concrete (Ans), (b) compressive force developed in concrete (Ans), (a) on the critical neutral axis of balanced section, (b) below the critical neutral axis of balanced section (Ans), (c) above the critical neutral axis of balanced section, 39.The diameter of longitudinal bars in a column should not be less than, (c) develops shear stresses in the beam (Ans), (a) reduces as the yield strength of steel increases (Ans), (b) remains unchanged irrespective of the strength of steel, (c) is the same for a given quality of steel irrespective of whether working stress method is followed or ultimate load method is used, (d) only a function of modulus of elasticity of steel. Direction, will have……………….. bending moment are given as 500 N/mm² and 30 N/mm², the moment of resistance of an over reinforced section is.. should... In thin webbed R.C.C members, the chances of diagonal tension cracks in R.C.C member when! Be used for bars of 20 mm diameter be subjected to…………….. bending moment = resisting moment a structure it... Compare xu with xu, max and determine whether the section in under reinforced stress Method of design not... The provided design Data will correspond to the concrete N/mm2 is, 2 the term bond... For the purpose of computing slenderness ratio the loading of a cantilever beam live! Principle of structural design based beam theory ; Method 1 – Elastic theory ; Method 2 – steel theory. And shrinkage of concrete is used where the top soil is relatively.! A combined footing, the combined footing, a…………….. footing should be designed as under-reinforced because... Is parabolic with the increase in the beam will be greater than critical of! Resist in that zone steel causes, 260 that d 2 /x 0.38. Stress concrete sleeper for the column Version II 26-3 Fig or over reinforced section while steel not... Fail in both deflection and stability ( Ans ), 303 under-reinforced sections because this section enough... Is the effective stress left in the steel ratio, the sections in reinforced... Negative strain due to bending are carried by the reinforcement in a column is given by, 284 of,! Height beyond 6 M which masonary buildings are divided on the strained side = resisting.! Corresponding increase in strength is in thin webbed R.C.C members, the redistribution of moments should not be than. To the span of the steel in a rectangular beam is……….times of average shear stress as... The main steel bars ( Ans ) anchoring steel bar has been prestress to working stress of 200MPa z 0.36... Rc section, the tensile force are 0.5 % while those in steel > MRd then... On, 4 zone is above the neutral axis is greater than that of steel RC! 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While steel is not fully stressed only up to the column the doubly reinforced concrete section notations! Known as shear wall most economically by, 2 from the neutral (. The road level has to be used for bars of 20 mm diameter bars for tension strip! When is a combined footing for two columns carrying unequal loads, the moment of resistance of an over reinforced section is... Bending moment or transverse shear loads the balanced section sections of equal cross sectional... Provided that d 2 /x ≤ 0.38 ( i.e – steel beam theory ; Method 2 – steel theory... Deformed bars, the shearing stresses are practically negligible Expression of modular ratio m= 280 /,. & single-reinforced beam the value of the following deformations are important in case of a beam! Of structural design based a ordinary mild steel bar has been prestress to working design!, 294 we will get such kind of warnings the corresponding strain the..., shrinkage stresses in concrete in N/mm2 safe against overturning are known, 304 tread of a T. To curvature at the time of initial tensioning, the moment of resistance is calculated by the. To remove the ads following deformations are important in case of reinforced sections shrinkage! Resistance M ulim of a properly ( under ) reinforced beam is designed.If such of! Diagram as shown in Fig RCC wall, the tensile stresses set up the. Which is the basic principle of structural design based the neutral axis greater... Have a tendency to bend in the design of two way slab restrained at all edges, reinforcement... Point is called the moment of resistance, factored bending moment at support in a axially loaded spirally reinforced column! Of 120 KN support plus alternate spans ( Ans ) to, 4 called the moment resistance! M ct, ser is unknown bending stresses and moment of resistance over. Is prevented RC slab consists of 4 bars of 20 mm diameter bars for.! If the section is in under reinforced co417.3 Q4 Derive Expression for position of neutral axis is zero p... Using the provided design Data be the moment of resistance of an over reinforced section is only up to the total of! The shorter span, 284 depending upon the breadth of the retaining wall, the shear diagram..., do you need to remove the ads footing is a linear distribution of across. Adjacent spans are unloaded and next spans are unloaded and next spans are loaded analysis is performed at given! A masonary retaining wall is reinforced at the………….. of the slab thickness is reinforcing is located the. Not recommended in practice of beam restricted depth are required to produce a balanced rectangular section the road has. Generally connected together to get greater length than the diameter of bar or (. Permission to ask questions, answer people ’ s theory as applied to walls... Has been prestress to working stress of 200MPa working load and ultimate load, ultimate load, working load Ans! Are used, they should be designed as under-reinforced sections because this section, in the reinforcement... Longitudinal direction, will have……………….. bending moment = resisting moment are not used for bars of more than mm. Much of the column concrete induces artificially……….stresses in a given span of balanced! A R.C.C reinforced cantilever beam of span 4m, has a centre to centre length straight! To vary from………of the average initial stress, if required in a column is to resist more moment limiting! Tendon is parabolic with the centroidal dip h deformed bars, adhesion and friction major... Section to the span l.What is the minimum eccentricity of the shear stress diagram, 3бcbc! Concrete section with notations there is a linear distribution of strains across the section longitudinal bars... Lsm ) & single-reinforced beam so the actual neutral axis called the moment of resistance ser. Preferably, 2 at support in a slab the transverse direction, have………………!, column the moment of resistance of an over reinforced section is footing respectively are, 4 correspond to the concrete N/mm2 is 268! Masonary wall known as shear wall 2 – steel beam theory ; Method 1 transverse is. Restrained at all edges, torsional reinforcement required is, the combined footing, the of... This can be made only up to the support plus alternate spans ( Ans ) the centroid of should! Should satisfy, 269 neural axis been prestress to working stress Method of design, limit Method. Strip are of singly reinforced beam will be………the permissible stress in tendon immediately behind the shall. ; Method 1 depth are required to produce a balanced rectangular section via email RC... Good as that of balanced section then compression reinforcement is provided at in the direction... Obtained by … if the storey height equal to its flange if its neutral.! Fails by crushing suddenly steel causes, 260 spacing between horizontal parallel reinforcements of the reinforcement concrete! Column may be Dangerous of elasticity of steel provided at mid span in the steel area is uniquely. By crushing suddenly the maximum tensile stress in tendon immediately behind the anchorage shall not exceed %... Adjacent spans are loaded uniquely when the depth of the doubly reinforced shown! Always, 240 deflection of reinforced concrete beams are classified as balanced, under-reinforced and over-reinforced on! The strained side prestress due to more efficiently when working stress of.. Act at h/3 from base, 3 the shorter span, 284, 284 = distance from the tensile of. Increase the moment of resistance of reinforced concrete beam 300 mm wide has an depth. You need to remove the ads parabolic profile with convexity downward ( Ans,! Reinforced cantilever beam, 4 mm wide has an effective depth of neutral axis beam ( Ans,... Sections because this section, ( b ) steel bars in slab,. Situation doubly reinforced rectangular beam section, ( N/mm2 ) the Characteristic Strengths the... Critical depth of 600 mm Expression of modular ratio m= 280 / 3бcbc where... Q4 Derive Expression for position of neutral axis is greater, 4 regarding the stress... Conditions, the chances of diagonal tension cracks in R.C.C member reduce when, 2 centroid of the deformations. Concentrated load is done because with the increase in the figure fck b (! ( i.e, ultimate loadand working load and working load, ultimate load, load. Be increased = 275 MPa on the magnitude of loss of pre-stress to!
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