Technical Review Board Rapid Seismic Risk Assessment Report. Manual

Transcription

1 Technical Review Board Rapid Seismic Risk Assessment Report Updated April 2017

2 Table of Contents Chapter Title 1.0 Introduction 2.0 Assessment Procedure 3.0 Assessment Forms Guide April, 17 Page 2 of 9

3 1. Introduction This manual outlines the assessment procedures for use with blocks that have been approved for Rapid Seismic Risk Assessments by the APEG BC Technical Review Board (TRB) or initiated by School District staff. 1.1 Assessment Overview The overall approach to the risk assessment of the blocks will be familiar to those who have been involved in the school retrofit process. The methodology that is presented here is very similar to the assessments that were completed in 2004, 2009 and 2010 for the Ministry of Education (MEd). Engineers carrying out these rapid assessments need to have attended the most recent Seismic Retrofit Guidelines (SRG) Seminar or otherwise completed the APEGBC video version of the training on the latest edition of SRG. At the time of the release of this document, SRG2 is in force with the SRG3 release planned for June 22, Following the SRG3 release in June, engineers will be required to have completed the SRG3 training to conduct Rapid Assessments. 1.2 Seismic Risk The seismic risk for the LDRS, Out of plane walls, and Diaphragms will be calculated using the SRG Analyzer. All engineers who have attended the training session will have been given access to the analyzer. Overall block risk will be assigned by the TRB Prototypes Prototype models need to be assigned to the predominant Lateral Deformation Systems (LDRS), diaphragms and out of plane walls for each block. SRG contains the list of all prototypes. April, 17 Page 3 of 9

4 1.3 Preliminary Retrofit Concepts As part of the risk assessment the engineers will provide basic information on the type of construction and a method of retrofit. This information will be of interest to others studying the block and may be used by MEd for global planning purposes Construction Types Almost thirty construction types, which are common to BC schools, have been summarized and described. During the assessment each block will be associated with whichever type of construction is the most representative for that block. This identifier will aid in establishing the composition of the existing building inventory. As most buildings are unique, the assessors will be provided with a place to comment on the particular variations exhibited by an assessed block Retrofit Options A list of more than twenty common retrofit methods has been provided. Assessors will recommend which of the retrofit options are to be used for the block being assessed, ensuring that at least one is selected for the LDRS, diaphragm and out of plane walls if applicable. Retrofit quantities or a sketch are not required. Each retrofit option describes the retrofit, the type of construction to which it is most commonly applied, examples of factors that affect the cost of construction and a sketch of the retrofit. As these are generic retrofit methods, they do not necessarily work seamlessly for all buildings. Assessors should indicate how the retrofit they envision is different from the retrofit options presented. April, 17 Page 4 of 9

5 1.4 Rapid Assessment Initiation & Contact Information When initiating a Rapid Assessment, please send an to the following TRB Steering Committee (TRBSC) representatives: Phillip Chambers, TRB Manager o phillipchambersconsulting@shaw.ca o Phone (250) John Wallace, TRBSC Chair o johnwallace@telus.net o Phone (604) Tim White o TWhite@bushbohlman.com o Phone (604) For any technical questions regarding the assessment forms or procedures, please contact Tim White or John Wallace. For any facilities questions about existing documentation or school protocols contact school board representatives in the appropriate district. For administrative questions please contact Phillip Chambers. April, 17 Page 5 of 9

6 2. Assessment Procedure The following is a summary of the steps one should follow to assess the blocks. 2.1 Obtain Drawings of Appropriate Block If you do not already have the drawing for the blocks you are assessing, contact your liaison at the appropriate school district and obtain copies. We are relying on the participating firms to coordinate this on their own. Please note the Rapid Seismic Risk Assessment Report has been recently amended to include a Block Drawing or Diagram of the Block in question. Please copy and paste a drawing into the last page of the report. 2.2 Review Past Assessments Review the past assessments of the school. These reports will not only serve as a reminder of the school, but also clearly define the extent and location of each block. Do not change the block area, designation or name from previous assessments. Changing these parameters makes it very difficult for MEd to manage the list of blocks that require retrofits. If you believe there is a serious issue please contact the TRB. Do not assess the whole school, only the block that has been specified. 2.3 Site Visit Site visits are recommended but not mandatory, if you are familiar with the school from previous projects. If you are new to the school, then you need to go to site to review and determine the relevance of the existing drawings. April, 17 Page 6 of 9

7 3. Assessment Forms Guide 3.1 General The assessment forms are now provided as a MS word document that you can edit. Please minimize changes to the base formatting, as consistency between reports is important for all involved. Before providing the completed report to your client, you must submit your report to the TRB for review. 3.2 Block Summary Municipality This field really represents the Seismic Location as opposed to the actual municipality the school may be located in. Enter whichever location you have used in the Analyzer here Number of Storeys Do not include crawlspaces, basements or attics Floor Area Provide the gross floor area of all occupied floors. Typically crawlspaces and attics are not included in this value. Use the value from previous assessments unless you believe they are significantly incorrect Site Class If no geotechnical study has been done identifying the Site Class for this school, use the soil hazard map from the most recent version of the SRG Previous Seismic Upgrades List any seismic upgrades listed in the documentation or observed on site. If the entire block was upgraded in 1990 or later the block usually does not need to be assessed Non Structural Seismic Deficiencies Use this area to identify items, other than heavy partition walls, that you feel pose a risk to life safety. April, 17 Page 7 of 9

8 3.2.7 Block Seismic Risk The seismic risk of the block will be based on the procedure outlined in SRG Volume 2 Chapter 20. This field will be of particular interest when reviewed by the TRB. 3.3 Block Construction Select any and all applicable types of construction. 3.4 Risk Analysis of Existing Structure Read SRG Volume 2 Chapter 20. This outlines the differences between retrofit design and risk analysis for SRG Lateral Deformation Resisting Systems (LDRS) Select the most appropriate prototype in each orthogonal direction and calculate the representative capacity. Use the analyzer to calculate PDE. If one orthogonal direction is made up of a combination of LDRS, use the toolbox method to derive the PDE but only write down the dominant LDRS. You may make comments indicating that this was done Out of plane Walls List the worst two types of out of plane walls that are in the block if applicable. Use the analyzer to determine the PDE of each type Diaphragms List the worst case diaphragm for the block here. Select the appropriate diaphragm type and run the analysis on the analyzer. If the diaphragm is ineffective, you will have to go back to both LDRS and Out of plane walls and consider the ramifications for each. Typically we recommend changing any outof plane prototypes to OP 1 or OP 2 (Cantilever wall/inadequate connection) where diaphragms are ineffective. For concrete diaphragms write CONC. See Section 7.4 in Volume 2 for how to determine seismic demand for concrete diaphragms. If the capacity meets the demand, then write OK if it is insufficient write NG. For horizontal steel braced frame diaphragms write HBF and use prototype S 1 April, 17 Page 8 of 9

9 to determine demand and to establish PDE. For storey height use the length of one bay Seismic Deficiencies and Comments This area is for the assessor to provide information not adequately captured in the assessment forms (e.g. torsional issues or problems or deficiencies with the vertical load bearing system that would compromise the seismic risk). Items such as major seismic deficiencies, building conditions and simple retrofit options are just a few of the items that can be listed here. Assessors are encouraged to make use of this space. Even simple statements like Weak lateral system will be useful for non engineers that wish to review this document but have no concept of what PDE means. 3.5 Preliminary Seismic Retrofit Concept Type of Construction The list of construction types can be found in Volume 8. Select the most appropriate and then indicate in the comments how the block differs from the descriptions given in Volume Retrofit Options Retrofit Details are found in SRG Volume 7. Without doing calculations, develop a retrofit scheme for the block, using the list of retrofit options provided. In the space provided, list up to five options you used in the retrofit scheme of the block. Do not list quantities. Do indicate what modifications to the documented description would have to be made to get them to work for this block. April, 17 Page 9 of 9