2017年-世界发展银行全球_Seismic_Risk_Reduction_Strategy_for_Public_School_Buildings_in_Peru_25页_2mb

Summary of Seismic Risk Reduction Strategy for Public School Buildings in Peru

Core Content

This technical note outlines a seismic risk reduction strategy for public school buildings in Peru, developed by the World Bank in collaboration with the Universidad de los Andes. It is based on a nationwide probabilistic seismic risk assessment and is part of a broader initiative to integrate disaster risk management into infrastructure sectors.

The strategy aims to reduce the risk of death or injury in the educational community, minimize damage to infrastructure, and ensure continuity of educational services during seismic events. The assessment includes a detailed methodology involving three main components: seismic hazard, exposure, and seismic vulnerability.

Main Objectives

• Reduce the risk of death or injuries from seismic events.
• Minimize damage to school infrastructure and protect property.
• Ensure minimal disruption of educational services.

Methodology Overview

The risk assessment methodology integrates:

• Seismic Hazard: Analyzed using peak ground acceleration maps, considering soil types and their dynamic amplification effects.
• Exposure: Based on a georeferenced database of school buildings, including replacement costs and structural characteristics.
• Seismic Vulnerability: Defined through functions that relate seismic intensity to expected damage or losses.

The study uses a probabilistic approach to estimate different risk metrics, including:

• Average Annual Loss (AAL): The expected annual economic loss from seismic events.
• Probable Maximum Loss (PML): The maximum loss expected over a certain return period (e.g., 100, 250, 500, and 1,000 years).

Key Findings

• The total number of public school facilities in Peru is 40,475, with 187,312 total buildings, of which 152,660 are for educational use.
• The total economic valuation of buildings for educational use is USD 8.4 billion.
• The most vulnerable structural typologies include Adobe (A), Unconfined Masonry (UCM), Precarious (P), Provisional (PROV), and 780-PRE modules, which are characterized by poor seismic performance.
• Connected villages have a higher concentration of risk in terms of AAL.
• The risk assessment results show that AAL is USD 190 million annually, with a PML of USD 590 million for a 1,000-year return period.

Intervention Strategy

Four main intervention options are proposed:

1. Conventional Retrofitting: Single-phase intervention to meet the E030 standard.
2. Incremental Retrofitting: Multi-phase intervention to achieve targeted performance levels.
3. Replacement by New Seismic-Resistant Buildings: Demolition of existing buildings and construction of new ones.
4. Contingent Intervention to Prevent Collapse: Temporary measures for highly vulnerable buildings.

Cost Estimation

• Total cost of interventions: USD 6,032 million.
• Subprograms:
  • Subprogram 1 (Replacement of HRC buildings): 97,110 buildings, USD 4,660 million.
  • Subprogram 2 (Conventional retrofitting): 39,933 buildings, USD 1,353 million.
  • Subprogram 3 (Low seismic hazard zones): 2,689 buildings, USD 19 million.

10-Year Program Cost

• Total number of buildings in the 10-year program: 108,629.
• Total cost of the 10-year program: USD 2,778 million.
• Subprogram 1 (Replacement by new construction): 73,645 buildings, USD 1,995 million.
• Subprogram 2 (Incremental retrofitting): 34,984 buildings, USD 783 million.

Prioritization Criteria

• Cost-effectiveness is calculated using the formula:
  $$
  CE = \frac{N_S \cdot (AAL_i - AAL_f)}{C}
  $$
  Where:

  • $CE$ = cost-effectiveness indicator
  • $N_S$ = number of potential students
  • $AAL_i$ = average annual loss at initial state
  • $AAL_f$ = average annual loss at final state
  • $C$ = cost of the proposed intervention

• Subprogram 2 (Incremental retrofitting) is more cost-effective in terms of number of students benefited.

• Subprogram 1 (Replacement of HRC buildings) is more effective in terms of seismic risk reduction.

Regional Disaggregation

• The intervention plan is designed to be implemented by region, with prioritization based on local seismic hazard levels and structural typologies.
• Comparative results for Lima and Amazonas show significant regional differences in seismic risk and building characteristics.
• The plan includes a breakdown of the total built area and number of buildings by intervention type for each region.

Conclusion

This study provides a comprehensive framework for seismic risk reduction in Peru’s public school infrastructure. It highlights the importance of addressing the most vulnerable buildings first, using a combination of retrofitting and replacement strategies. The methodology and results can serve as a model for other countries facing similar challenges in seismic risk management.