Note for Prestressed Concrete - PC By Karthik M P

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SSM INSTITUTE OF ENGINEERING AND TECHNOLOGY, DINDIGUL DEPARTMENT OF CIVIL ENGINEERING COURSE CODE & NAME : CE 6702 PRESRESSED CONCRETE STRUCTURES YEAR & SEMESTER : IV & VII BRANCH : CIVIL ENGINEERING COURSE INSTRUCTOR : M.P.KARTHIK ACADEMIC YEAR : 2016 -2017

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CONTENTS SL. NO. DESCRIPTION PAGE NO. UNIT -1 INTRODUCTION - THEORY AND BEHAVIOUR 1 INTRODUCTION 1 2 BASIC PRINCIPLE OF PRESTRESSING 2 3 APPLICATIONS OF PRESTRESSED CONCRETE 2 4 ADVANTAGES & DISADVANTAGES OF PRESTRESSED CONCRETE 3 5 USES OF PRESTRESSED CONCRETE 3 6 DEFINITIONS 4 7 DEGREE OF PRESTRESSING 6 8 PRESTRESSING SYSTEM - PRETENSIONING SYSTEM 7 9 PRESTRESSING SYSTEM - POSTTENSIONING SYSTEM 8 10 ANALYSIS OF PRESTRESS MEMBER 10 11 PRESSURE LINE OR THRUST LINE 15 12 LOAD BALANCING CONCEPT 20 13 DEFLECTIONS 23 14 LOSSES IN PRESTRESS 25 UNIT - 2 DESIGN FOR FLEXURE AND SHEAR 15 BASIC ASSUMPTIONS FOR CALCULATING FLEXURAL STRESSES 32 16 TYPES OF FLEXURAL FAILURE 32 17 FRACTURE OF STEEL IN TENSION 33 18 STRAIN COMPATIBILITY METHOD 35 19 SIMPLIFIED CODE PROCEDURES 38 20 DESIGN OF PRETENSIONED AND POST TENSIONED FLEXURAL MEMBERS 44 21 DESIGN OF PRETENSIONED BEAMS 46 22 DESIGN OF POSTTENSIONED BEAMS 53

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UNIT - 3 DEFLECTION AND DESIGN OF ANCHORAGE ZONE 23 FACTORS INFLUENCING DEFLECTIONS 62 24 LIMITS OF DEFLECTION 62 25 LIMIT STATE OF SERVICEABILITY 65 26 ANCHORAGE 66 27 BURSTING FORCES IN ANCHORAGE ZONES 71 28 STRESS DISTRIBUTION IN END BLOCKS 72 29 MAGNEL'S METHOD 74 30 GUYON’S METHOD: 77 31 ANCHORAGE ZONE REINFORCEMENT 81 UNIT - IV COMPOSITE BEAMS AND CONTINUOUS BEAMS 32 COMPOSITE STRUCTURAL MEMBERS 88 33 ADVANTAGES IN USING PRECAST PRESTRESSED UNITS 88 34 TYPES OF COMPOSITE CONSTRUCTION 89 35 ANALYSIS OF STRESSES: 91 36 DIFFERENTIAL SHRINKAGE 93 37 DEFLECTION OF COMPOSITE MEMBERS 97 38 STRESSES AT SERVICEABILITY LIMIT STATE 98 39 FLEXURAL STRENGTH OF COMPOSITE SECTIONS 99 40 DESIGN OF COMPOSITE SECTIONS 100 UNIT - V MISCELLANEOUS STRUCTURES 41 DESIGN OF NON-CYLINDERICAL PIPES 101 42 CIRCUMFERENTIAL PRESTRESSING 102 43 DESIGN OF CYLINDER PIPES 109 44 WATER TANKS 111 45 PARTIAL PRESTRESSING 115

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Prestressed Concrete Structures UNIT- I INTRODUCTION – THEORY AND BEHAVIOUR 9 Basic concepts – Advantages – Materials required – Systems and methods of prestressing – Analysis of sections – Stress concept – Strength concept – Load balancing concept – Effect of loading on the tensile stresses in tendons – Effect of tendon profile on deflections – Factors influencing deflections – Calculation of deflections – Short term and long term deflections Losses of prestress – Estimation of crack width. Introduction: The idea of prestressed concrete has been around since the latter decades of the 19th century, but its use was limited by the quality of the materials at the time. It took until the 1920s and ‘30s for its materials development to progress to a level where prestressed concrete could be used with confidence. Freyssinet in France, Magnel in Belgium and Hoyer in Germany were the principle developers. The idea of prestressing has also been applied to many other forms, such as: Force-fitting of metal bands on wooden barrels The metal bands induce a state of initial hoop compression, to counteract the hoop tension caused by filling of liquid in the barrels. Pre-tensioning the spokes in a bicycle wheel The pre-tension of a spoke in a bicycle wheel is applied to such an extent that there will always be a residual tension in the spoke. Force-fitting of metal bands on wooden barrel M.P.Karthik, AP/Civil, SSMIET, Dgl Pre-tensioning the spokes in a bicycle wheel Page 1