calculate the percentage loss of stress in wires if (a) the beam is pre- tensioned and (b) the beam is post-tensioned, using the following data: es = 210 kn/mm 2 and e c = 35 kn/mm 2; relaxation of stress in steel = 5 percent of the initial stress; shrinkage of concrete = 300 x 10-6 for pretensioning and 200 x 10-6 for post tensioning; creep b) Extreme alignment 6. Loss of head is incurred by fluid mixing which occurs at fittings such as bends or valves, and by frictional resistance at the pipe wall. The energy loss due to noise and vibration in the apparatus was assumed to be about 0.5%. 10. Calculate the maximum stress to be applied to the wires at the jack?a) 900n/mm2b) 960n/mm2c) 850n/mm2d) 800n/mm2Answer: bClarification: Px = 600n/mm2, e = 2.7183, = 0.5Px = Pe-,600 = Pe-(0.5/2),P = (600) (2.71830.79) = 1320n/mm2, Average stress in wires = (1320+600/2) = 960n/mm2. Head loss - (Measured in Meter) - Head loss is a measure of the reduction in the total head (sum of elevation head, velocity head and pressure head) of the fluid as it moves through a fluid system. 2. Add your answer and earn points. Coulomb friction, named after Charles-Augustin de Coulomb, is an approximate model used to calculate the force of dry friction. For members constructed and prestressed in a single stage, relative to the stress immediately before transfer, the loss may be taken as: View Answer, 9. Most Asked Technical Basic CIVIL | Mechanical | CSE | EEE | ECE | IT | Chemical | Medical MBBS Jobs Online Quiz Tests for Freshers Experienced . none of these: Answer: Option B. View Answer, 2. 3.2.12 Skin friction drag. Concept: Loss of stress due to relaxation of steel Relaxation is assumed to mean the loss of stress in steel under nearly constant strain at constant temperature. 8. Typical boundary layer velocity profiles for laminar and turbulent flows are shown in Fig. The decrease in stress in steel as a result of decreased strain of the steel, such as results from shrinkage and creep of the concrete in a prestressed concrete unit. Length effect: The stress at any distance 'x' is given as: P x = P 0 e k x Where K is Wobble correction Loss at distance x due to length effect = P o - P x 2. Friction due to surface irregularity- When two objects come into contact, they create friction due to surface irregularities. A post tensioned concrete beam 200mm wide and 450mm deep, of span 10m, initial stress of 840n/mm2 is available in the un jacked end immediately after the anchoring. The Indian standard code recommends a value varying from 0 to 90 N/mm2 for stress in wire varying from 0.5 fup to 0.8 fup . Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. Friction is reduced by _____ (a) Ball bearings (b) Glass (c) Both of these (d) None of these. Frictional losses can be reduced by several methods: Over tensioning the tendons by an amount equal to the maximum frictional loss 6 days ago, Posted Due to shrinkage stresses, a simply supported beam having reinforcement only at bottom tends to a) deflect downward b) deflect upward PRESTRESS LOSS DUE TO WOBBLE FRICTION (Ref. Like a concrete column getting more compressed, or a beam bending. This stress is complex but is essentially shear along with compressive and tensile. b) 0.12 This set of Prestressed Concrete Structures Multiple Choice Questions & Answers (MCQs) focuses on Loss Due to Friction. Based on the observation, about 2 per cent loss occurs in pre-tensioned members, whereas about 3 per cent loss of stress occurs in post-tension members . 3. c) 850n/mm2 The candidates who will get qualified in the prelims are eligible to attend the mains. View problem 2 on loss of stress due to friction.pdf from CIVIL 001 at Osmania University. Find the angle between tangents to the cable at supports?a) 0.13b) 0.12c) 0.10d) 0.23Answer: bClarification: b = 200mm, d = 450mm, l = 10m, r = 84m, d = 5m,Angle between the horizontal tangent drawn to the cable at support sin = (5/84) = 0.06radians,Cumulative angle between tangents to the cable at supports = (20.06) = 0.12radians. The friction between tendon and duct due to change of duct profile. Therefore I have come up with the following equation to solve for the coefficient of kinetic friction . Bearing friction loss generally depends on the type of bearing used and on the viscosity of the lubricant. Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. ii) . To know more check the a) 4 types The loss due to friction is the summation of losses due to these two effects. area of contact only [B]. The thinner the fluid, the lesser the fluid friction will be, and vice versa. f = 64/Re The friction factor for turbulent flow depends strongly on the relative roughness. View Answer, 10. 1ACoouale beam of Prustnsed by dleep, s Cable i Cable ta oo Nmm TSDrmm bdlow at Cable Ond 200 All surfaces contain hills and valleys found when zoomed . 1. 12 days ago, Posted The amount of static friction depends only upon the nature of the surfaces in contact, rather than the area of the surfaces in contact. The surface shear stress ( w) depends on the viscosity of the . a) 150mm 4. The experimentally observed linear relationship between the macroscopic static friction coefficient and the critical length l c indicates that the imprint corresponds to the stress distribution when the propagation length of the precursor reaches l c, which is maintained after the subsequent precursor has passed. 2007-2022 Learnify Technologies Private Limited. SOLUTION p = function (D v ) = K Da vb c d p is pressure per metre [p] = ML-2T-2 [D] = L -1-1T-1 loss due to creep,friction and shrinkage.docx - Free download as Word Doc (.doc / .docx), PDF File (.pdf), Text File (.txt) or read online for free. is the friction coefficient, and it is used to evaluate friction losses, the value of related to duct material. only in post-tensioned beams only in pretensioned beams in both post-tensioned and preten-sioned beams none of the above The temperature reinforcement in the vertical slab of a T-shaped R.C. 9 days ago, Posted b) 1-(+Kx) View Answer, 6. The losses of prestress due to creep and shrinkage of concrete and the relaxation of the steel are all time- dependent and inter-related to each other. 2.What is friction? The wobble or wave effect is the result of accidental or unavoidable misalignment. Due to the relaxation of steel, the prestress in the tendon is . Use the following data: RELAXATION OF STEEL Loss due to Relaxation of Stress in Steel Loss of Stress due to Friction. (a) Shape (b) Size (c) Shape and size both (d) None of these. Privacy Policy, 1. View Answer, 7. 56. d) Exterior point Friction is a/an _____ (a) Evil (b) Foe (c) Evil and foe both (d) None of these. (2) Why does friction not depend upon area of contact_ - Quora - View presentation slides online. depends upon the type of wedges and the stress in the wires. a) Post tensioned members c) Tensile alignment This preview shows page 1 - 3 out of 3 pages. In systems where the tendons are Exams 100+ PYPs & Mock Test, KPSC Assistant Engineer Civil Mock Test 2020, Maharashtra Subordinate Services Group B Mock Test, MPSC Subordinate Services Previous Year Papers, MPSC Assistant Town Planner Previous Year Papers, MPSC Livestock Development Officer Previous Year Papers, MPSC Motor Vehicle Inspector Previous Year Papers, MPSC Food Safety Officer Previous Year Papers, MPSC Assistant Commissioner Food Previous Year Papers, MPSC Assistant Director Previous Year Papers, MPSC Assistant Public Prosecutor Previous Year Papers. 5. Share this: Twitter; Facebook; Related posts: . Examples of Bad News & Good News Messages (Memos) . The gradual reduction of this introduced compressive stress in a prestressed member due to various reasons is called losses of prestress. Pages 277 This preview shows page 184 - 186 out of 277 pages. Home Prestressed Concrete Structures Objective Questions 250+ TOP MCQs on Loss Due to Friction and Answers. In the case of post tensioned members the tendons are housed in ducts preformed in concrete. c) Chemical members The various types of losses in prestress. The ducts are either straight or follow a curved profile depending upon the design requirements. On what force friction depends? 2. LOSS OF STRESS DUE TO FRICTION: On tensioning the curved tendons, loss of stress occurs in the post-tensioned members due to friction between the tendons and the surrounding concrete ducts. (adsbygoogle = window.adsbygoogle || []).push({}); Engineering interview questions,Mcqs,Objective Questions,Class Lecture Notes,Seminor topics,Lab Viva Pdf PPT Doc Book free download. Loss due to curvature effect, which depends upon the tendon form or alignment, which generally follows a curved profile along the length of the beam. Prestress loss due to friction occurs. 7 days ago, Posted Losses in pre-stressing are listed below: Post tensioning: Elastic deformation (No losses if all the wires are simultaneously tensioned but losses are recorded if the bars are successively tensioned), Relaxation of stress in steel, Shrinkage of concrete, Creep of concrete, Friction, Anchorage slip. The action of the frictional shear stresses on the surface of the body leads to a frictional drag force, opposing the motion of the body through the fluid. The loss of stress due to curvature effect depends upon ____________ A cylindrical concrete tank, 40m external diameter is to be prestressed circumferentially by means of a high strength steel wire (Es = 210kn/mm2) jacked at 4 points and 90 degrees apart. 5. KPSC Assistant Engineer Mock Previous Year Question Paper. Loss of stress due to elastic deformation of concrete depends upon (a) relaxation of steel (b) friction and anchorage slip (c) modular ratio, 2. The loss of stress due to friction is given as ____________ a) 1- (+Kx) b) 1- (+Kx) c) 1- (+Kx) d) 1- (+Kx) View Answer 7. b . The total loss of prestress due to friction is of ____________a) 4 typesb) 2 typesc) 8 typesd) 3 typesAnswer: bClarification: The total loss due to friction is divided into two types:Loss of prestress due to effect of curvature, Loss of prestress due to wobble effect and frictional losses can be reduced by over tensioning the tendons by an amount equal to the maximum frictional loss and jacking the tendons from both ends of the beam adopted generally, when the tendons are long or when the angles of bearing are large. This sums up to be 18%. ---- >> Below are the Related Posts of Above Questions :::------>>[MOST IMPORTANT]<, Your email address will not be published. It is determined by the Colebrook equation. The loss of stress due to curvature effect depends upon ____________a) Alignmentb) Midpointc) Centerlined) Exterior pointAnswer: aClarification: The loss of stress due to the curvature effect, which depends upon the tendon form or alignment which generally follows a curved profile along the length of the beam, curvature coefficient is expressed as and wobble coefficient is expressed as k/m. Stress times the true area of contact is equal to the friction force, F=S x A. In addition, there may be losses due to sudden . I am inclined to answer no because according to my equation it depends on acceleration, but on the other hand acceleration . a) Alignment The method of obtaining f will depend on whether the flow . Only if you are an existing PayPal customer. Losses of prestress depend on the va Continue Reading David Wilmshurst Get plagiarism-free solution within 48 hours, Submit your documents and get free Plagiarism report, By creating an account, you agree to our terms & conditions, We don't post anything without your permission, (Rate this solution on a scale of 1-5 below), Log into your existing Transtutors account. The friction factor for laminar flow is independent of roughness of the pipe's inner surface. problem 2 on loss of stress due to friction.pdf - 1ACoouale beam of Prustnsed by dleep, s Cable i Cable ta oo Nmm TSDrmm bdlow at Cable Ond 200. Other related documents. 463 pre stress loss due to friction occurs c shape of. Scribd is the world's largest social reading and publishing site. View Answer. d) 3 types A cylindrical concrete tank, 40m external diameter is to be prestressed circumferentially by means of a high strength steel wire (Es = 210kn/mm2) jacked at 4 points and 90 degrees apart. b) Midpoint The loss of stress due to the curvature effect, which depends upon the tendon form or alignment which generally follows a curved profile along the length of the beam, curvature coefficient is expressed as and wobble coefficient is expressed as k/m. 3. The wobble or wave effect is the result of accidental or unavoidable misalignment. . Prestressed Concrete Structures Objective Questions, 250+ TOP MCQs on Loss Due to Shrinkage and Answers, 250+ TOP MCQs on Loss Due to Anchorage Slip and Answers, 250+ TOP MCQs on Loss Due to Creep of Concrete and Answers, 250+ TOP MCQs on Loss Due to Elastic Deformation and Answers, 250+ TOP MCQs on Nature of Losses and Answers, 250+ TOP MCQs on Loss Due to Relaxation of Stress in Steel and Answers, 250+ TOP MCQs on Loss of Head due to Friction in Viscous Flow and Answers, 250+ TOP MCQs on Principles and Classifications of Prestressing and Answers, 250+ TOP MCQs on Need and Terminology and Answers, 250+ TOP MCQs on Types of Friction and Answers, 250+ TOP MCQs on Concrete Sleepers and Answers, 250+ TOP MCQs on Design for Shear and Torsion and Answers, 250+ TOP MCQs on Laws of Solid Friction and Limiting Friction and Answers, 250+ TOP MCQs on Stresses in Tendons and Answers, 250+ TOP MCQs on Shear and Principal Stresses and Answers, 250+ TOP MCQs on Tensioning Devices and Answers, 250+ TOP MCQs on Basic Assumptions and Answers, 250+ TOP MCQs on Prestressed Concrete Structures Basic Concepts and Answers, 250+ TOP MCQs on Historic Development and Answers, 250+ TOP MCQs on Long Term Deflections and Answers. 9. c) Type of steel This loss is associated with the angular change of duct profile. During compaction several types of friction occur as follows: (a) friction between moving punches and die wall, which is relatively small and pressure loss caused by it is particularly negligible . 463 Pre stress loss due to friction occurs C Shape of aggregates D All the above. a) Misalignment The amount of Frictional force by a fluid on an object depends upon the following: 1. c) Bubble effect Find the expected extension at the jack? View Answer, 4. Clarification: The loss due to elastic deformation of concrete depends on the modular ratio and the average stress in concrete at the level of steel, consider a post tensioned member which is prestressed by a single tendon and the shortening of concrete occurs till the tendon is jacked and no shortening of concrete is observed after it. In the above expression L is the length of pipe, D its diameter, and v the average velocity of flow. both (a) and (b) [D]. The loss of stress due to friction is given as ____________ Question: Coefficient of friction depends upon [A]. We store cookies data for a seamless user experience. 2. c) 8 types Loss of prestress due to shrinkage of concrete depends upon (a) modulus of elasticity of concrete (b) stress in concrete at level of steel (c) shrinkage strain, 3. The total loss of prestress due to friction is of ____________ a) 4 types Consequently on tensioning the curved tendons, loss of stress occurs in the post tensioned members due to friction between the tendons and the surrounding concrete ducts. b) 130mm It is similar to creep of concrete. View Answer, 3. Find the angle between tangents to the cable at supports? Answer: a Clarification: Loss of prestress due to friction occurs in the case of post tensioned members, the tendons are housed in the ducts performed in concrete and the ducts are either straight or follow a curved profile depending upon the design requirements. 5. A concrete tank if has a minimum stress in wires 600n/mm2 immediately after tensioning and the coefficient of friction is 0.5.
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