Major Changes in Concrete-Related Provisions-1997 UBC and Beyond

2000 ◽  
Vol 16 (1) ◽  
pp. 141-162
Author(s):  
S. K. Ghosh
Keyword(s):  
Seismic Design ◽  
Building Code ◽  
Earthquake Hazards ◽  
Structural Concrete ◽  
Seismic Codes ◽  
Evolutionary Changes ◽  
Reduction Program ◽  
Design Requirements ◽  
New Buildings ◽  
Made In

U.S. seismic codes are undergoing profound changes as of this writing. Changes from the 1994 to the 1997 edition of the Uniform Building Code (UBC) (ICBO 1994, 1997) are many and far-reaching in their impact. The 1997 edition of the National Earthquake Hazards Reduction Program (NEHRP) Recommended Provisions for Seismic Regulations for New Buildings (BSSC 1998) contains further evolutionary changes in seismic design requirements beyond those of the 1997 UBC. The latter document will form the basis of the seismic design provisions of the first edition of the International Building Code (IBC), to be published in the spring of 2000. This paper first discusses the major changes that have been made in the concrete-related provisions from the 1994 to the 1997 edition of the UBC. The paper gives background to these changes, provides essential details on them, and indicates how they have been or how they are going to be incorporated (at times with significant modifications) into the 1997 NEHRP Provisions and the 2000 IBC. The newly published ACI 318-99, Building Code Requirements for Structural Concrete (ACI 1999), is going to be adopted by reference into the 2000 IBC. This entails further changes in concrete-related provisions beyond the 1997 UBC. Some of the more important of these changes are discussed here. A small number of amendments and additions to the ACI 318-99 provisions are going to be included in the 2000 IBC. The more important of these are also outlined in this paper.

Ground motion amplification factors for the proposed 2005 edition of the National Building Code of Canada

2003 ◽  
Vol 30 (2) ◽  
pp. 272-278 ◽  
Author(s):  
W.D Liam Finn ◽  
Adrian Wightman
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Building Code ◽  
Soil Conditions ◽  
Site Conditions ◽  
Amplification Factors ◽  
Seismic Codes ◽  
Local Soil ◽  
Recent Developments ◽  
Site Classes

Foundation factors are used in seismic codes to capture the amplification effects of local soil conditions on ground motions and, hence, on seismic design forces. Recent developments in categorizing site conditions for seismic codes and assigning intensity- and frequency-dependent amplification factors to the various site classes are presented to provide a basis for understanding the new foundation factors proposed for the 2005 edition of the National Building Code of Canada.Key words: design spectra, site characterization, amplification factors.

Performance-Based Research of Existing Reinforced Concrete Building Structure Seismic Evaluation and Reinforcement Technology

2014 ◽  
Vol 513-517 ◽  
pp. 3500-3503
Author(s):  
Li Na Pei
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Seismic Evaluation ◽  
Seismic Codes ◽  
Performance Targets ◽  
Existing Structures ◽  
Moderate Earthquake ◽  
Story Drift ◽  
Capacity Calculation ◽  
New Buildings

Based on the current seismic codes, the elastic capacity calculation under frequent earthquake and ductile details of seismic design should be used for both seismic design of new buildings and seismic evaluation of existing buildings to satisfy the seismic fortification criterion, namely/no damage under frequent earthquake, repairable under moderate earthquake, and no collapse under severe earthquake0. For the evaluation, rebuilding and extending of existing structures which dissatisfy the ductile details of current seismic codes, the elastic capacity calculation under frequent earthquake is obviously not enough. In this paper, the advanced performance-based seismic theory is introduced while story drift ratio and deformation of component are used as performance targets to solve the problems of seismic evaluation and strengthening for existing reinforced concrete structures.

scholarly journals Risk-adjusted Design Basis Earthquake’s Adequacy for use in Seismic Design Codes

2021 ◽  
Author(s):  
Mohammad Zaman ◽  
Mohammad Reza Ghayamghamian
Keyword(s):  
Seismic Design ◽  
Peak Ground Acceleration ◽  
Design Parameters ◽  
Design Codes ◽  
Acceptance Criteria ◽  
Ground Acceleration ◽  
Seismic Codes ◽  
Residual Drift ◽  
Design Basis ◽  
Made In

Abstract In most buildings’ seismic design codes design basis peak ground acceleration (PGADBE) is provided by employing a uniform-hazard approach. However, a new trend in updating seismic codes is to adopt a risk-informed method to estimate the PGADBE so-called risk-adjusted design basis peak ground acceleration (PGARDBE). An attempt is made here to examine the adequacy of the PGARDBE to fulfill the assumptions made in seismic codes for converting the maximum considered earthquake’s (MCE) intensity to PGADBE. To this end, the performance of regular intermediate steel moment frames (IMF) is assessed in terms of collapse margin (CMR) and residual drift ratios in the event of MCE and design basis earthquake (DBE), respectively. The PGARDBEs are computed for Karaj County, Iran. A set of 96 index archetypes of regular IMF are designed considering four design parameters, which include the number of stories (2, 3, 6, 9, 12, and 15), span lengths (4 and 8 meters), occupancies (residential and commercial), and seismic demands (0.15, 0.25, 0.35 and 0.45g). The PGADBE prescribed by Standard No. 2800 for Karaj neither meets the assumed acceptance criteria nor stands on the safe side. Meanwhile, PGARDBE fulfills the acceptance criteria but does not necessarily satisfy the implicit assumption made in codes that the code-conforming buildings have at least a CMR of 1.5 if the MCE occurs. This emphasizes that the PGARDBE should not be used without examining the CMR fulfillment. The results recommend that a lower limit need to be set on PGARDBEs, which is found to be 0.35g for Karaj. Outcomes also reveal that the code-conforming buildings designed with the proposed PGARDBE can fulfill both repairability and life safety performances at the DBE and MCE, respectively. These buildings also have a high chance to be even considered as repairable ones at the seismic demand of MCE. Furthermore, regardless of the employed method for estimating PGADBE, various relationships between design parameters with different performance indicators such as CMR, residual drift ratio, ductility demand, imposed drift ratio, and building’s normalized weight are presented. These relationships can be used to evaluate the buildings’ safety factor against collapse and repairability, justification of using IMF in regions with high seismicity, level of structural and nonstructural damage as well as the economic consequence of changes in PGADBE. The presented relationships provide a multi-criteria decision-making tool to decide on the optimum PGADBE leading to an affordable alternative and tolerable damage.

Decentralized shared computers in the National Earthquake Hazards Reduction Program

1981 ◽  
Author(s):  
Peter L. Ward ◽  
James Herriot ◽  
William F. Jolitz
Keyword(s):  
Earthquake Hazards ◽  
Reduction Program

Evolution of seismic design codes of highway bridges in Chile

2021 ◽  
pp. 875529302098801
Author(s):  
José Wilches ◽  
Hernán Santa Maria ◽  
Roberto Leon ◽  
Rafael Riddell ◽  
Matías Hube ◽  
...  
Keyword(s):  
Seismic Design ◽  
Failure Modes ◽  
Highway Bridges ◽  
Design Codes ◽  
Seismic Codes ◽  
Analysis And Design ◽  
Residual Displacements ◽  
Shear Keys ◽  
Maule Earthquake ◽  
2010 Maule Earthquake

Chile, as a country with a long history of strong seismicity, has a record of both a constant upgrading of its seismic design codes and structural systems, particularly for bridges, as a result of major earthquakes. Recent earthquakes in Chile have produced extensive damage to highway bridges, such as deck collapses, large transverse residual displacements, yielding and failure of shear keys, and unseating of the main girders, demonstrating that bridges are highly vulnerable structures. Much of this damage can be attributed to construction problems and poor detailing guidelines in design codes. After the 2010 Maule earthquake, new structural design criteria were incorporated for the seismic design of bridges in Chile. The most significant change was that a site coefficient was included for the estimation of the seismic design forces in the shear keys, seismic bars, and diaphragms. This article first traces the historical development of earthquakes and construction systems in Chile to provide a context for the evolution of Chilean seismic codes. It then describes the seismic performance of highway bridges during the 2010 Maule earthquake, including the description of the main failure modes observed in bridges. Finally, this article provides a comparison of the Chilean bridge seismic code against the Japanese and United States codes, considering that these codes have a great influence on the seismic codes for Chilean bridges. The article demonstrates that bridge design and construction practices in Chile have evolved substantially in their requirements for the analysis and design of structural elements, such as in the definition of the seismic hazard to be considered, tending toward more conservative approaches in an effort to improve structural performance and reliability for Chilean bridges.

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