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ACI MNL 3 2020

$73.13

ACI MNL-3(20): Guide to the Code for Assessment, Repair, and Rehabilitation of Existing Concrete Structures

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ACI 2020
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Advancements in the practice of assessment, repair, rehabilitation, and strengthening of concrete structures have developed through a collaboration of design professionals, contractors, suppliers, manufacturers, researchers, educators, and lawyers. The annual cost to owners for repair, protection, and strengthening of existing concrete structures is estimated between 8 and 1 billion (Vision 2020). Simply put, even sound concrete may require repair, rehabilitation, maintenance, or strengthening throughout the service life of a structure. Accordingly, from 2004 to 2006, the Strategic Development Council (SDC), an interindustry development group dedicated to supporting the concrete industry’s strategic needs, facilitated the development of “Vision 2020: A Vision for the Concrete Repair, Protection, and Strengthening Industry” to establish a set of goals that would improve the efficiency, safety, and quality of concrete repair and protection activities. One of the goals established by Vision 2020 was to create a concrete repair and rehabilitation code by 2015. The ACI 562-13 standard, “Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings and Commentary,” is the end result of that initiative. ACI 562-19 is the third edition of the Code with revisions, additions, and reorganized information to enhance the Code, providing more clarity and additional, updated information to assist the design professional. The purpose of the ACI 562 Code is to provide minimum material and design requirements for the assessment, repair, and rehabilitation of structural concrete members. Like other ACI codes, ACI 562 is organized in a dual-column format, with mandatory code provisions to the left of each page, and nonmandatory commentary to the right to provide additional guidance and information on the content presented in the Code provisions. Unlike other ACI standards, ACI 562 includes both prescriptive and performance requirements. The performance requirements provide great latitude and flexibility to the licensed design professional in satisfying the requirements of ACI 562. Accordingly, ACI 562 serves to unify and strengthen concrete assessment, repair, and rehabilitation projects while accommodating the diverse and unique strategies and materials used in the industry. In general, the overall use and function of ACI 562, with respect to existing concrete structures, can be compared to that of ACI 318-19, “Building Code Requirements for Structural Concrete and Commentary,” with new concrete construction. As with ACI 318 and the 2018 International Building Code (2018 IBC), plans are underway for ACI 562 an ANSI standard, to be adopted into the International Existing Building Code (IEBC) to address matters pertaining to assessment, repair, rehabilitation, and strengthening of concrete members within existing buildings. Local jurisdictions and building authorities can also adopt ACI 562 directly. Cities and states have both adopted ACI 562 and adopted use of ACI 562 on specific projects. Other jurisdictions are in the process of reviewing the Code for consideration and adoption. Accordingly, while ACI 562 currently defines the standard for the concrete assessment, repair, and rehabilitation industry, the code provisions of ACI 562 will likely then become mandatory requirements as part of the governing building codes that regulate work in existing buildings. Overview of the guide to ACI 562 Code content The primary purpose of this guide is to help licensed design professionals (LDPs) gain more knowledge, skill, and judgment to interpret and properly use the ACI 562 Code. Although specifically developed for LDPs, this guide also provides insight into the use and benefits of ACI 562 for contractors, material manufacturers, and building owners and building officials. To achieve this goal, the guide is separated into three main components: Chapter Guides including Appendix A, Project Examples, and Appendix B, providing an overall view of the new standard, ACI 563, “Specifications for Repair of Concrete in Buildings.” The Chapter Guides and Project Examples are provided in tandem for clarity and understanding of the relative portions of ACI 562 Code. The Project Examples illustrate the process of carrying out a concrete building assessment, repair, rehabilitation, or strengthening project from inception through completion. This guide, including the Project Examples, is intended as a supplement to the ACI 562 Code and not as a “how-to” manual for performing concrete assessment, repair, rehabilitation, or strengthening. Several additional documents are referenced in ACI 562 Commentary and this guide to assist in evaluating the various options and approaches to performing successful concrete assessment, repair, rehabilitation, or strengthening projects. The intent of each Project Example is not to be a prescriptive formula for each of the project scenarios presented, but to illustrate how various sections of ACI 562 are applied together to execute the project. For convenience, related provision numbers from ACI 562 are given at the top of each corresponding paragraph of the project example text. Eight Project Examples are included within the guide: 1. Typical parking structure repairs 2. Typical façade repairs 3. Repair of historic structure for adaptive reuse 4. Strengthening of two-way flat slab 5. Strengthening of double-tee stems for shear 6. Concrete beam repair by section enlargement 7. Concrete repair by steel jacket 8. Beam repair with fire protection analysis: a. Beam strengthening due to live load increase b. Beam with inadequate existing concrete cover In the third edition of this repair guide, a new chapter, Appendix B, was added to address specifications. This is another goal by Vision 2020 to create a concrete repair specification standard. The ACI 563-18 standard, “Specification for Repair of Concrete in Buildings,” is a reference standard that the LDP can apply to any construction repair and rehabilitation project involving structural concrete by citing it in the Project Specifications. It provides direction to the contractor and clearly defines the responsibilities and scope of the repair, rehabilitation, or strengthening. The specifications detail the work, material, and installation required to complete a project the way the client wants. The Chapter Guides follow the general organization of ACI 562, broken down by the corresponding sections of ACI 562. Section numbers in Chapters 1 to 10 and Appendix A of this guide correspond to the provision numbers in ACI 562. The Chapter Guides include background information and an explanation of the various ACI 562 provisions, with particular insight into how the particular chapter and section of the Code fit within the project. Where applicable, flowcharts are provided to illustrate how to navigate the various provisions of ACI 562. References to Project Examples are provided where applicable to illustrate how specific provisions within each chapter of ACI 562 are incorporated into the design process. In some instances, additional limited-scope examples are included to better illustrate a point that is not covered by the Project Examples. The first edition of ACI 562 was published in 2013, and was not available when the work for the projects discussed in the Project Examples was actually performed. All Project Examples assume that ACI 562 was available and accepted by local jurisdiction when the example projects were performed. The second edition of ACI 562, published in 2016, includes additional definitions used in the Code for consistency with 2018 IEBC and other similar standards for existing structures. The title of ACI 562-16 was changed by replacing the word “Evaluation” with “Assessment.” The two terms, which are used interchangeably by other standards and the first version of this Code, have received distinct definitions in the second edition of ACI 562 (Stevens et al. 2016). Specific criteria requirements for assessment and design of repair and rehabilitation for varying levels of damage, deterioration, or faulty construction was added in Chapter 4 when using the Code with IEBC, and in Appendix A when using the Code as a stand-alone code. Chapters 1 and 4 were revised to include specific criteria requirements for assessment and design of repair and rehabilitation for varying levels of damage, deterioration, or faulty construction. Load combinations in Chapter 5, which define the minimum strength of a structure with unprotected external reinforcement, were revised. Chapter 6 directs the LDP to provide an assessment before rehabilitation of an existing structure. This chapter includes historical material property data to help the design professional in the assessment if existing documents related to the existing structure are not available or physical samples cannot be extracted, because of the historical value of the structure. The interface bond provisions in Chapter 7 were revised to provide specific requirements based on shear test, as well as when to provide interface reinforcement, and commentary in Chapter 8 was clarified. The third edition of ACI 562, published in 2019, has: (a) Added text to simplify use of new materials that have the equivalent of an ICC-ES evaluation report in Chapter 1; (b) Simplified the requirements for the basis of design reported in Chapter 1; (c) Clarified requirements related to detailing of existing reinforcing steel in Chapter 7; and (d) Updated commentary in Chapter 8 to include a listing of exposure categories that may affect durability. In addition, three new repair examples are added to demonstrate the flexibility of the Code and its applicability to different repair and strengthening methods. Example 6 is related to concrete beam repair by section enlargement, Example 7 addresses concrete frame strengthening by steel jacketing, and Example 8 focuses on the effect of fire on concrete members and possible protection based on two scenarios: scenario one—concrete structure subjected to increase in live load; and scenario two—reinforcement with low concrete cover. Lastly, a summary of the various provisions of ACI 562, as well as the corresponding location where each provision is covered within the guide, is provided in the Provision Coverage Matrix at the end of this guide. This serves as a useful tool when searching for additional information to a specific provision of ACI 562.

PDF Catalog

PDF Pages PDF Title
7 Acknowledgments
8 Preface
13 About This Book
14 Chapter 1—General Requirements
1.1—General
15 1.2—Criteria for the assessment and design of repair and rehabilitation of existing concrete structures
16 1.3—Applicability of the Code
17 1.4—Administration
1.5—Responsibilities of licensed design professional
1.6—Construction documents
1.7—Preliminary assessment
20 Chapter 2—Notation and Definitions
2.1—Notation
2.2—Definitions
22 Chapter 3—Referenced Standards
24 Chapter 4—Basis for Compliance
25 4.2—Compliance method
26 4.3—Potentially dangerous structural conditions
27 4.4—Substantial structural damage
4.5—Conditions of deterioration, faulty construction, or damage less than substantial structural damage
31 4.6—Conditions of deterioration, faulty construction, or damage less than substantial structural damage without strengthening
4.7—Additions, 4.8—Alterations, 4.9—Changes in occupancy
32 Chapter 5—Loads, Factored Load Combinations, and Strength Reduction Factors
33 5.1—General
34 5.2—Load factors and load combinations
5.3—Strength reduction factors for repair design
5.4—Strength reduction factors for assessment
35 5.5—Additional load combinations for structures rehabilitated with external reinforcing systems
38 Chapter 6—Assessment, Evaluation, and Analysis
39 6.2—Investigation and structural evaluation
41 6.3—Material properties
45 6.4—Test methods to determine or confirm material properties
46 6.5—Structural analysis of existing structures
6.6—Structural serviceability
6.7—Structural analysis for repair design
47 6.8—Strength evaluation by load testing
6.9—Recommendations
48 Chapter 7—Design of Structural Repairs
7.1—General
7.2—Strength and serviceability
49 7.3—Behavior of repaired systems
50 7.4—Interface bond
58 7.5—Materials
7.6—Design and detailing considerations
59 7.7—Repair using supplemental post-tensioning
60 7.8—Repair using fiber-reinforced polymer (FRP) composites
61 7.9—Performance under fire and elevated temperatures
62 Chapter 8—Durability
63 8.2—Cover
8.3—Cracks and deterioration of reinforcement and metallic embedments
64 8.4—Corrosion
65 8.5—Surface treatments and coatings
66 Chapter 9—Construction
9.1—General
9.2—Stability and temporary shoring requirements
67 9.3—Temporary conditions
69 9.4—Environmental issues
70 Chapter 10—Quality Assurance
10.1—General
71 10.2—Inspection
10.3—Testing of repair materials
10.4—Construction observations
72 Chapter 11: Commentary References
74 Appendix A—Criteria when Using ACI 562 as a Stand-Alone Code
A.1—General
A.2—Design-basis code criteria
76 A.3—Potentially dangerous structural conditions
77 A.4—Substantial structural damage
A.5—Conditions of deterioration, faulty construction, or damage less than substantial structural damage
79 A.6—Conditions of deterioration, faulty construction, or damage less than substantial structural damage without strengthening
80 A.7—Additions
81 A.8—Alterations
83 A.9—Changes in occupancy
84 Appendix B—Repair Guide
General
Section 1—General requirements
85 General procedures
Preinstallation conference
86 Quality assurance, quality control, testing, and inspection
Quality assurance (QA)
88 Advantages of quality assurance
Disadvantages of quality assurance
Quality control (QC)
Advantages of quality control
Disadvantages of quality control
89 Testing and inspection
91 Section 2—Shoring and bracing
92 Section 3—Concrete removal and preparation for repair
95 Section 4—Formwork
98 Section 5—Reinforcement and reinforcement supports
100 Section 6—Conventional concrete mixtures
102 Section 7—Handling and placing of conventional concrete
103 Section 8—Proprietary cementitious and polymer repair materials
Sections 9 and 10
Notes to Specifier (nonmandatory)
Checklists
105 Project Examples
106 Chapter 12: Project Example 1—Typical Parking Structure Repair
Description of structure
Project initiation and objectives
107 Governing building codes
108 Preliminary assessment
Investigation of existing site conditions
109 Capacity and demand of existing structure
Findings of preliminary assessment
110 Area 1
112 Area 2
114 Report to owner
Structural Assessment
Existing conditions
115 Structural analysis for repair design
116 Area 1
Area 2
117 Design of structural repairs and durability
Slab area 1
118 Slab Area 2 and columns
119 Slab soffit repairs
Construction specifications
120 Construction
Quality assurance
121 Project close-out
Periodic maintenance
Record documents
122 Chapter 13: Project Example 2—Typical Façade Repair
Description of structure
123 Project initiation and objectives
Governing building codes
124 Preliminary observations and assessment
125 Observed concrete conditions
126 Laboratory findings
Findings
127 Structural assessment and repair design
Shear wall reveal strip repairs
129 North and south walls away from reveal strips and east and west slab and column edges
Balcony repairs
131 Performance under fire and elevated temperatures
Contract specifications
132 Construction
Quality assurance
133 Project close-out
Periodic maintenance
Record documents
134 Chapter 14: Project Example 3—Adaptive Reuse of Historic Depot
Description of structure
135 Project initiation and objectives
Governing building codes
136 Preliminary observations and evaluation
Concrete conditions
138 Material evaluation findings
Summary
139 Structural assessment
Requirement for structural assessment
Existing properties
Structural analysis
140 Structural analysis findings
141 Recommended repair program
Train deck rehabilitation
143 Column rehabilitation
145 Concrete repair details
147 Contract specifications
149 Construction
Quality assurance
Project close-out
Periodic maintenance
Record documents
150 Chapter 15: Project Example 4—Parking/Plaza Slab Strengthening
Description of structure
Project initiation and objectives
Governing building codes
151 Preliminary evaluation
Document review
Existing site conditions
Strength of as-built structure
154 Compliance method and design-basis code
155 Structural assessment
Requirement for structural assessment
Structural assessment
156 Structural analysis
Strengthening concepts
Strengthening Concept 1
Strengthening Concept 2
157 Assessment of strengthening concepts
158 Structural analysis for repair design
160 Design of structural repairs and durability
161 Contract specifications
164 Construction
Quality assurance
Load test
Test procedure
168 Test results
169 Project close-out
Periodic maintenance
Record documents
170 Chapter 16: Project Example 5—Precast/Prestressed Double-Tee Repair
Description of structure
Project initiation and objectives
171 Governing building codes
172 Preliminary assessment
Existing site conditions
Design strength of existing structure
Findings of preliminary assessment
174 Design-basis code
Structural evaluation
Existing site conditions
175 Structural analysis for evaluation
177 Structural safety
Repair/replacement options
Repair/replacement Option 1
178 Repair/replacement Option 2
Repair/replacement Option 3
179 Repair/replacement Option 4
180 Evaluation of repair/replacement options
Design of strengthening repairs
Structural analysis for repair design
181 Design of strengthening repairs
182 Design of structural repairs and durability
Development and bond of CFRP strips
183 Acceptance of CFRP repairs by the authorities having jurisdiction
Durability of repairs
Aesthetics of repairs
Contract specifications
184 Construction
Quality assurance
187 Project close-out
Periodic maintenance
Record documents
188 Chapter 17: Project Example 6—Concrete Beam Repair by Section Enlargement
Description of structure
Project initiation and objectives
189 Governing building code
190 Structural assessment
Structural analysis
191 Repair options
192 Design of repairs
193 Durability of repairs
194 Contract documents
Construction specifications
Construction
Quality assurance / construction observations
195 Project Close-out
Periodic maintenance
Record documents
196 Chapter 18: Project Example 7—Concrete Frame Strengthening by Steel Jacket
Description of structure
Project initiation and objectives
197 Governing building codes
Preliminary evaluation
200 Strengthening concepts
Structural analysis and repair design
201 Durability
Contract documents
Construction specifications
204 Construction
Quality assurance
205 Project close-out
Periodic maintenance
Record documents
206 Chapter 19: Project Example 8—Building Subjected to Fire
Description of structure
207 Project initiation, objectives, and remediation summary
209 Fire resistance rating calculations
218 Contract specifications
219 Construction
Quality assurance
Load test
Test procedure
220 Project close-out
Periodic maintenance
Record documents
References
222 Referenced Standards and Reports
225 Authored documents
ACI MNL 3 2020
$73.13