Public Disclosure Authorized Public Disclosure Authorized PRACTICAL SEISMIC DESIGN AND CONSTRUCTION MANUAL FOR RETROFITTING SCHOOLS IN THE KYRGYZ REPUBLIC Public Disclosure Authorized Svetlana Brzev and Ulugbek Begaliev Public Disclosure Authorized © 2018 The World Bank 1818 H Street NW, Washington DC 20433 Telephone: 202-473-1000; Internet: www.worldbank.org Some rights reserved This work is a product of the staff of The World Bank with external contributions. Note that The World Bank does not necessarily own each component of the content included in the work. The World Bank therefore does not warrant that the use of the content contained in the work will not infringe on the rights of third parties. The risk of claims resulting from such infringement rests solely with you. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, the Executive Directors of The World Bank or the governments they represent. 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Practical Seismic Design and Construction Manual for Retrofitting Schools in the Kyrgyz Republic. © World Bank” Cover photos: Svetlana Brzev All queries on rights and licenses, including subsidiary rights, should be addressed to World Bank Publications, The World Bank Group, 1818 H Street NW, Washington, DC 20433, USA; fax: 202-522-2625; e-mail: [email protected]. TABLE OF CONTENTS ACKNOWLEDGMENTS 1. INTRODUCTION 1.1 Overview 1-1 1.2 Purpose, Objectives, and Goals 1-2 1.3 Audience and Beneficiaries 1-3 1.4 Scope 1-3 1.5 Organization of the Document 1-3 1.6 Key Resources 1-4 1.7 Disclaimer 1-5 2. SEISMIC HAZARD SETTING AND SEISMIC DESIGN APPROACHES 2.1 Introduction 2-1 2.2 Seismic Hazard in the Kyrgyz Republic 2-1 2.2.1 History of past earthquakes in the Kyrgyz Republic 2-1 2.2.2 Seismic zoning maps 2-4 2.3 Seismic Design Approaches 2-7 2.3.1 Force-based versus performance-based seismic design approach 2-7 2.3.2 Limitations of the force-based seismic design approach for seismic evaluation and retrofit of existing buildings 2-8 2.4 Seismic Design According to СНиП КР 20-02:2009 2-10 2.4.1 Spectral Method 2-10 2.4.2 Seismic resistance (capacity) verification according to СНиП КР 20-02:2009 2-13 2.4.3 Verification of earthquake-induced lateral displacements according to СНиП КР 20-02:2009 2-13 2.5 A Primer on the Performance-Based Seismic Design 2-13 2.5.1 Background 2-13 2.5.2 Seismic performance levels and seismic performance objectives 2-14 2.5.3 Nonlinear analysis procedures 2-17 2.5.4 Nonlinear static (pushover) analysis 2-18 2.6 Seismic Analysis of Nonstructural Building Elements 2-22 2.7 References 2-24 3 BUILDING TYPOLOGIES FOR SCHOOLS IN THE KYRGYZ REPUBLIC 3.1 Introduction 3-1 i 3.2 Earthquake Effects on Buildings 3-1 3.3 Seismic Deficiencies 3-3 3.4 An Overview of Building Typologies for Schools in the Kyrgyz Republic 3-5 3.5 Masonry School Building Typologies 3-7 3.5.1 Unreinforced masonry with wooden floors (EMCA 11) 3-7 3.5.2 Confined masonry buildings with precast RC floors (EMCA 13) 3-11 3.6 RC School Building Typologies 3-15 3.6.1 Monolithic RC moment frame with brick infill walls (EMCA 23) 3-15 3.6.2 Precast RC frame with exterior precast RC panels (EMCA 34) 3-20 3.7 Current Seismic Assessment Approaches in the Kyrgyz Republic 3-30 3.8 Past Seismic Assessment Studies of School Buildings in the Kyrgyz Republic 3-30 3.9 References 3-31 4 SEISMIC RETROFITTING STRATEGIES AND TECHNIQUES FOR REINFORCED CONCRETE AND MASONRY BUILDINGS 4.1 Introduction 4-1 4.2 Seismic Retrofitting Process 4-1 4.3 Performance Objectives for Retrofitted Buildings 4-2 4.3.1 Selection of performance objectives 4-2 4.3.2 Seismic assessment of existing buildings: force-based versus performance-based approaches 4-3 4.4 Feasibility of Seismic Retrofitting 4-3 4.5 Retrofitting Strategies 4-4 4.5.1 Enhancement of ductility, capacity and/or stiffness of the building 4-4 4.5.2 Local versus global retrofitting 4-5 4.6 Addition of New Structural Elements 4-6 4.6.1 Addition of reinforced concrete shear walls 4-8 4.6.2 Addition of steel bracings 4-14 4.7 Seismic Retrofitting Techniques for Reinforced Concrete Buildings 4-20 4.7.1 Background 4-20 4.7.2 RC jacketing of existing RC beams and columns 4-20 4.7.3 Steel jacketing of RC frame members 4-27 4.7.4 Jacketing using Fiber Reinforced Polymer (FRP) overlays 4-28 4.8 Seismic Retrofitting Techniques for Masonry Buildings 4-32 4.8.1 Background 4-32 4.8.2 Use of RC jacketing/reinforced plaster for seismic retrofitting of masonry walls 4-33 ii 4.8.3 Use of Fiber Reinforced Polymer (FRP) overlays and strips for seismic retrofitting of existing masonry walls 4-38 4.9 Comparisons of Seismic Retrofitting Techniques for Reinforced Concrete and Masonry Buildings 4-41 4.10 Seismic Retrofitting of Horizontal Floor and Roof Diaphragms 4-44 4.10.1 Seismic deficiencies addressed by this retrofit technique 4-44 4.10.2 Description 4-44 4.10.3 Analysis and design considerations 4-45 4.10.4 Detailing and construction considerations 4-47 4.10.5 Design applications and performance in past earthquakes 4-47 4.10.6 Design codes and guidelines 4-47 4.11 References 4-47 5 RETROFIT CASE STUDY 1: REINFORCED CONCRETE FRAME BUILDING 5.1 Building Description 5-1 5.2 Numerical Model of the Existing Building 5-8 5.2.1 Description of the model and the key modelling assumptions 5-8 5.2.2 Material properties 5-10 5.2.3 Seismic weight 5-11 5.3 Seismic Evaluation of the Existing Building 5-11 5.3.1 Linear elastic analysis (Spectral Method) 5-11 5.3.2 Nonlinear static (pushover) analysis 5-17 5.3.3 Effect of the welded beam-to-column connection on nonlinear behavior and failure mechanism of RC frames (pushover analysis) 5-23 5.4 Seismic Retrofit Schemes 5-28 5.5 Retrofit Scheme 1 (RS1): RC Jacketing of Existing Columns 5-29 5.5.1 An overview of the retrofit scheme 5-29 5.5.2 Numerical model 5-29 5.5.3 Linear elastic analysis (Spectral Method) 5-31 5.5.4 Nonlinear static (pushover) analysis 5-34 5.5.5 Design of retrofitted columns with RC jackets 5-37 5.5.6 Typical construction details: RS1 5-37 5.5.7 Construction procedure: RS1 5-37 5.5.8 Construction cost estimates: RS1 5-38 5.6 Retrofit Scheme 2 (RS2): RC Jacketing of the Existing Columns and New Steel Braces 5-44 iii 5.6.1 An overview of the retrofit scheme 5-44 5.6.2 Numerical model 5-45 5.6.3 Linear elastic analysis (Spectral Method) 5-46 5.6.4 Nonlinear static (pushover) analysis 5-50 5.6.5 Design of steel braces 5-52 5.6.6 Typical construction details: RS2 5-52 5.6.7 Construction procedure: RS2 5-53 5.6.8 Construction cost estimates: RS2 5-53 5.7 Retrofit Scheme 3 (RS3): New RC Shear Walls 5-58 5.7.1 An overview of the retrofit scheme 5-58 5.7.2 Numerical model 5-60 5.7.3 Linear elastic analysis (Spectral Method) 5-62 5.7.4 Nonlinear static (pushover) analysis 5-65 5.7.5 Design of new RC shear walls and foundations 5-69 5.7.6 Typical construction details: RS3 5-70 5.7.7 Construction procedure: RS3 5-70 5.7.8 Construction cost estimates: RS3 5-71 5.8 A Comparison of Retrofit Schemes RS1, RS2, and RS3 5-73 5.9 References 5-75 6 RETROFIT CASE STUDY 2: MASONRY SCHOOL BUILDING 6.1 Building Description 6-1 6.2 Numerical Model of the Existing Building 6-5 6.2.1 Description of the model and key modelling assumptions 6-5 6.2.2 Material properties 6-6 6.2.3 Seismic weight 6-6 6.3 Seismic Evaluation of the Existing Building 6-7 6.3.1 Seismic analysis parameters 6-7 6.3.2 Dynamic properties of the structure 6-8 6.3.3 Capacity evaluation of the existing building 6-9 6.3.4 Displacements 6-11 6.4 Seismic Retrofit Schemes 6-12 6.5 Retrofit Scheme 1 (RS4): RC Jacketing of Existing Masonry Walls 6-12 6.5.1 An overview of the retrofit scheme 6-12 6.5.2 Numerical model 6-13 6.5.3 Linear elastic analysis (Spectral Method) 6-17 iv 6.5.4 Design of retrofitted walls with RC jacketing 6-18 6.5.5 Typical construction details: RS4 6-20 6.5.6 Construction procedure: RS4 6-22 6.5.7 Construction cost estimates: RS4 6-23 6.6 Retrofit Scheme 5 (RS5): Carbon Fiber Reinforced Polymers (CFRP) 6-28 6.7 A Comparison of the Seismic Retrofit Schemes 6-29 6.8 References 6-30 APPENDICES A.