CONTENTS 1.INTRODUCTION 1 2.CONCEPTUAL DESIGN AND PLANNING CONSIDERATIONS 7 Building Shape 7 Non-Symmetric Layout 9 Masonry Infill Walls 10 Out-of-plane seismic resistance of masonry infills 12 Short and Captive Columns 13 Modifications of Existing Buildings 15 Alterations 15 Vertical A dditions 15 Adjacent Buildings: Pounding Effect 16 Soft and Weak Stories 17 How to A void Soft Stories 19 Strong Beam-Weak Column Failure 20 3.DETAILING CONSIDERATIONS 23 On Ductility 23 Beams 24 Failure modes 24 Location and amount of horizontal rebars 24 Stirrups 27 Columns 27 Failure modes 27 Vertical rebars 27 Horizontal ties 28 Beam-Column Joints 30 Masonry Infill Walls 33 Non-Structural Elements 34 4 CONSTRUCTION CONSIDERATIONS 37 Material Quality 37 Selection and Control of Materials 38 Preparation, handling and curing of concrete 38 Selection and control of steel 39 Workmanship 40 Inspection 42 5.ALTERNATIVES TO RC FRAMES WITH INFILLS IN REGIONS OF HIGH SEISMIC RISK 43 Why are the Alternatives Needed 43 The Alternatives 43 Confined Masonry Buildings 44 Background 44 Advantages 45 RC Frame Buildings with RC Shear Walls 46 Background 46 Advantages 48 6.RETROFITTING RC FRAME BUILDINGS 51 Introduction 51 Vulnerability Assessment 52 Ways to Strengthen Existing RC Frame Buildings 52 Installation of New RC Shear Walls or Steel Braces 53 Jacketing 56 Strengthening of Existing Masonry Infills 60 Strengthening RC Frame Buildings with Open Ground Floor 60 Short-term Goal = Prevent Collapse 61 Long-term Goal = Ensure Good Earthquake Behavior 62 How Seismic Retrofit Affects Structural Characteristics 62 Retrofitting RC Frames with Masonry Infills: Implementation Challenges 63 7.CONCLUSIONS 65 Technical Challenge65 Stakeholders 65 Closing Comments 66 8 REFERENCES 67