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.

Validation of seismic design parameters for wood-frame shearwall systems

2002 ◽  
Vol 29 (3) ◽  
pp. 484-498 ◽  
Author(s):  
Ario Ceccotti ◽  
Erol Karacabeyli
Keyword(s):  
Seismic Design ◽  
Peak Ground Acceleration ◽  
Time History ◽  
Design Parameters ◽  
Ground Acceleration ◽  
Frame Building ◽  
Current Design ◽  
Wood Frame ◽  
Design Earthquake ◽  
Nonlinear Time History

A methodology for assessment of seismic design parameters for a wood-frame shearwall system is developed, consisting of a test program of shearwalls and the application of nonlinear time history analyses to a four-storey wood-frame building that was designed to resist the seismic requirements for Vancouver, British Columbia. Analyses employed 22 selected earthquake accelerograms that were scaled upwards until an ultimate peak ground acceleration (Au) was reached where the shearwall reached a "near-collapse" state. The 22 values of Au were found to be greater than the "design" peak ground acceleration, indicating the adequacy of the current design procedures for the particular shearwalls investigated. The influence of gypsum wallboard on the behaviour of the shearwalls was also evaluated, and a new force modification factor "R" for walls composed of a mixture of wood-based and gypsum panels was proposed. The effect of flexibility of floor diaphragms was considered separately for a symmetric building and was found to have 5-30% reduction on the Au values obtained for the rigid diaphragm case.Key words: seismic design, earthquake loads, timber structures, wood shearwalls.

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.

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.

scholarly journals Vulnerability and site effects in earthquake disasters in Armenia (Colombia) – Part 2 : Observed damage and vulnerability

2021 ◽  
Vol 21 (8) ◽  
pp. 2345-2354
Author(s):  
Francisco J. Chávez-García ◽  
Hugo Monsalve-Jaramillo ◽  
Joaquín Vila-Ortega
Keyword(s):  
Peak Ground Acceleration ◽  
Relative Frequency ◽  
Site Effects ◽  
Building Stock ◽  
Ground Acceleration ◽  
Vulnerability Evaluation ◽  
Observed Damage ◽  
Made In

Abstract. Damage in Armenia, Colombia, for the 25 January 1999 (Mw=6.2, peak ground acceleration (PGA) 580 Gal) event was disproportionate. We analyze the damage report as a function of number of stories and construction age of buildings. We recovered two vulnerability evaluations made in Armenia in 1993 and in 2004. We compare the results of the 1993 evaluation with damage observed in 1999 and show that the vulnerability evaluation made in 1993 could have predicted the relative frequency of damage observed in 1999. Our results show that vulnerability of the building stock was the major factor behind damage observed in 1999. Moreover, it showed no significant reduction between 1999 and 2004.

Development of Indian standards in EQ resistant design of bridges – past, present and future prospects

2021 ◽  
Author(s):  
Alok Bhowmick ◽  
Harpreet Singh
Keyword(s):  
Seismic Design ◽  
Soil Condition ◽  
Reduction Factor ◽  
Design Parameters ◽  
Seismic Zone ◽  
Ground Acceleration ◽  
Response Reduction Factor ◽  
Local Soil ◽  
Importance Factor ◽  
Indian Railway

<p>Evolution of seismic design provisions in various Indian Standards over the last 50 years have been reviewed in this paper. Seismic provisions of Bureau of Indian Standards (BIS) code (IS 1893), Indian Road Congress (IRC) standard (IRC:6 &amp; IRC:SP:114) and Indian Railway standards (IRS code) are compared. Design parameters for comparison include the seismic zone factor / peak ground acceleration, importance factor, local soil condition, design spectra and response reduction factor.</p>

scholarly journals Seismic Design Value Evaluation Based on Checking Records and Site Geological Conditions Using Artificial Neural Networks

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Tienfuan Kerh ◽  
Yutang Lin ◽  
Rob Saunders
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Seismic Design ◽  
Neural Network Model ◽  
Peak Ground Acceleration ◽  
Epicentral Distance ◽  
Ground Acceleration ◽  
Comparison Results ◽  
Geological Conditions ◽  
Design Value

This study proposes an improved computational neural network model that uses three seismic parameters (i.e., local magnitude, epicentral distance, and epicenter depth) and two geological conditions (i.e., shear wave velocity and standard penetration test value) as the inputs for predicting peak ground acceleration—the key element for evaluating earthquake response. Initial comparison results show that a neural network model with three neurons in the hidden layer can achieve relatively better performance based on the evaluation index of correlation coefficient or mean square error. This study further develops a new weight-based neural network model for estimating peak ground acceleration at unchecked sites. Four locations identified to have higher estimated peak ground accelerations than that of the seismic design value in the 24 subdivision zones are investigated in Taiwan. Finally, this study develops a new equation for the relationship of horizontal peak ground acceleration and focal distance by the curve fitting method. This equation represents seismic characteristics in Taiwan region more reliably and reasonably. The results of this study provide an insight into this type of nonlinear problem, and the proposed method may be applicable to other areas of interest around the world.

scholarly journals Seismic and Structural Analyses of the Eastern Anatolian Region (Turkey) Using Different Probabilities of Exceedance

2021 ◽  
Vol 4 (4) ◽  
pp. 89
Author(s):  
Ercan Işık ◽  
Ehsan Harirchian ◽  
Aydın Büyüksaraç ◽  
Yunus Levent Ekinci
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Seismic Moment ◽  
Peak Ground Acceleration ◽  
Earthquake Ground Motion ◽  
Earthquake Risk ◽  
Ground Acceleration ◽  
Earthquake Parameters ◽  
Seismic Design Code

Seismic hazard analysis of the earthquake-prone Eastern Anatolian Region (Turkey) has become more important due to its growing strategic importance as a global energy corridor. Most of the cities in that region have experienced the loss of life and property due to significant earthquakes. Thus, in this study, we attempted to estimate the seismic hazard in that region. Seismic moment variations were obtained using different types of earthquake magnitudes such as Mw, Ms, and Mb. The earthquake parameters were also determined for all provincial centers using the earthquake ground motion levels with some probabilities of exceedance. The spectral acceleration coefficients were compared based on the current and previous seismic design codes of the country. Additionally, structural analyses were performed using different earthquake ground motion levels for the Bingöl province, which has the highest peak ground acceleration values for a sample reinforced concrete building. The highest seismic moment variations were found between the Van and Hakkari provinces. The findings also showed that the peak ground acceleration values varied between 0.2–0.7 g for earthquakes, with a repetition period of 475 years. A comparison of the probabilistic seismic hazard curves of the Bingöl province with the well-known attenuation relationships showed that the current seismic design code indicates a higher earthquake risk than most of the others.

Analisis Percepatan Tanah Puncak Akibat Gempa Pada Kota Sorong Sebagai Upaya Mitigasi Bencana

2018 ◽  
Vol 4 (2) ◽  
pp. 14
Author(s):  
Imam Trianggoro Saputro ◽  
Mohammad Aris
Keyword(s):  
Peak Ground Acceleration ◽  
Ground Acceleration ◽  
Papua Barat

Sorong merupakan salah satu kota yang terletak di Provinsi Papua Barat. Daerah ini memiliki tingkat kerentanan yang tinggi terhadap ancaman bahaya gempa bumi karena lokasinya terletak di antara pertemuan lempengan tektonik dan beberapa sesar aktif. Tingkat kerawanan terhadap gempa pada daerah ini cukup tinggi. Pada September 2016, BMKG mencatat bahwa terjadi gempa bumi dengan skala magnitudo sebesar 6,8 SR (Skala Ritcher) dengan kedalaman 10 meter dari permukaan laut dan berjarak 31 km arah timur laut kota Sorong. Gempa ini bersifat merusak. Akibat gempa ini, sebanyak 62 orang terluka dan 257 rumah rusak. Untuk itu diperlukan suatu analisis terhadap percepatan tanah puncak (Peak Ground Acceleration) terbaru sebagai langkah mitigasi yang nantinya dapat digunakan untuk perencanaan gedung tahan gempa.Pengumpulan data gempa pada peneltian ini yaitu data gempa yang terjadi sekitar kota Sorong pada rentang waktu 1900-2017. Data gempa yang diambil adalah yang berpotensi merusak struktur yaitu dengan magnitudo (Mw) ≥ 5 dengan radius gempa 500 km dari kota Sorong dan memiliki kedalaman antara 0 - 300 km. Setelah diperoleh data gempa maka dibuat peta sebaran gempa di wilayah kota Sorong. Percepatan tanah puncak dihitung berdasarkan fungsi atenuasi matuscha (1980) dan menggunakan pendekatan metode Gumbel.Hasil penelitian menunjukkan bahwa nilai percepatan tanah puncak (PGA) di wilayah kota Sorong pada periode ulang 2500 tahun atau menggunakan probabilitas terlampaui 2% dalam 50 tahun umur rencana bangunan diperoleh sebesar 708.9520 cm/dt2 atau 0.7227 g. Apabila melihat peta gempa SNI 1726-2012 yang menggunakan probabilitas yang sama maka nilai percepatan tanah puncak (PGA) ketika gempa bumi berkisar antara 0.4 g - 0.6 g. Nilai ini mengalami peningkatan yang berarti tingkat resiko terhadap gempa bumi pada wilayah kota Sorong meningkat.

Up-flow roughing filtration: rehabilitation of a water treatment plant in Tarata, Bolivia

1998 ◽  
Vol 37 (9) ◽  
pp. 105-112 ◽  
Author(s):  
Ana María Ingallinella ◽  
Luis María Stecca ◽  
Martin Wegelin
Keyword(s):  
Water Treatment ◽  
Pilot Plant ◽  
Laboratory Tests ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Horizontal Flow ◽  
Design Parameters ◽  
Sand Filters ◽  
Chemical Products ◽  
Made In

This paper presents the methodology used for the rehabilitation of the pretreatment stage in a water treatment plant for a village located in Bolivia which has 3500 inhabitants. The treatment plant was initially composed by horizontal-flow roughing filters and slow sand filters, but due to the high contents of colloidal turbidity of the providing source, it did not work properly. A plan of rehabilitation was made which comprised laboratory tests, pilot tests and proposal of modifications based on the results of previous stages. The laboratory tests were made in order to find the optimum conditions to coagulate the raw water. It was found that horizontal-flow roughing filters must be turned into up-flow roughing filters, so a pilot plant was built and was operated for three months in order to find suitable design parameters. The results obtained obtained during the operation of the pilot plant and the proposal of modifications are presented. The results of operation of the final plant, which are also reported, demonstrated the advantages of the up-flow roughing filtration as a pretreatment stage when it is necessary to add chemical products in small treatment plants.

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