Earthquake-resistant Standards Research Articles

Private housing compliance with public seismic safety measures after 2015 Gorkha earthquake in Nepal

After the Gorkha earthquake in 2015, the Nepalese government introduced a series of seismic-resistant building designs to reconstruct and repair residential dwellings. The objective of this research was to explore the extent of compliance with the new prescribed or recommended seismic-resistant features in rebuilt residential structures in two Nepal districts that were severely damaged during the earthquake. The primary source of data was a field survey conducted with a structural questionnaire among 332 affected households during October and November 2022. The survey also utilized informal interviews at three study sites in August 2023, with results showing that 95%–97 % of total respondents reconstructed their houses according to earthquake-resistant standards. The same percentage of respondents withdrew the final payment from the National Reconstruction Authority (NRA). Most reconstructed houses were smaller than before the earthquake; many respondents rebuilt one-room, one-story structures. In addition, housing typologies at the study sites changed from brick/stone and mud-based masonry to cement-based construction. Key Words: Gorkha earthquake, seismic-resistant guidelines, compliance with government safety measures, reconstructed houses, NRA.

Study on the Application of Earthquake Resistant Standards (Sni 1726:2019) Against Building in Yogyakarta City

The load-bearing structure is made from a special moment-bearer frame structure. The structure is planned against earthquake loads by the earthquake resistance planning standard for building structures, or Indonesian National Standard 1726:2019, has a 2,500-year return period, and is based on an earthquake strategy. The response spectrum method possesses an Earthquake Resistance Planning foundation. Procedure for Buildings is used in the earthquake load analysis and Non-Building Structures (Indonesian National Standard- 726: 2012 and Indonesian National Standard 1726: 2019). This study aims to make a comparison between the two procedures in terms of changes in seismic bottom shear forces and to examine the building structure's performance in terms of the inter-level drift that occurs. The results of dynamic analysis obtained using the ETABS v.19.0.0 program showed an increase in seismic bottom shear force by 133%, both in the X direction and in the Y direction. The result directions were also compared by using the 2012 Indonesian National Standard. Judging from the terms of deviation between levels, the building structure does not exceed the provisions, either according to the 2012 or 2019 Indonesian National Standard.

Comparative study of seismic spectra of great magnitude occurred in Chile between 2012 to 2022 and the design spectra of seismic standard NCH433

In this document, a study of the spectra of large-magnitude seismic records that occurred in Chile between 2012 and 2022 is presented, comparing them with the design spectra of NCh433 and D. S 61. For this, seismic records greater than Mw = 6 have been used, with different depths to the hypocenter and with different types of soil. The catastrophes caused by earthquakes with magnitudes greater than Mw = 6 in the last decade in seismic zones (Turkey and Syria, 2023; Pakistan, 2013; Iran, 2014; Ecuador, 2016 or, Mexico, 2017; among others), have called into question the requirements structural aspects of earthquake-resistant standards in the world. That is why this work aims to demonstrate that highly seismic areas such as Chile, prone to having earthquakes with magnitudes greater than Mw = 6, have seismic-resistant regulations updated to the existing reality. The aim is to demonstrate whether the design spectra of the Standard have been sufficiently representative to determine the calculation accelerations used in the structural design of buildings. It is concluded that many of the spectral accelerations of the records that occurred in Chile exceed those of the design spectrum of the Standard, especially for short periods. Finally, in this research, new design spectra composed of 3 intervals (the 2nd interval is a plateau) are proposed that are more adjusted to the existing seismic reality in Chile during the last decade, considering the type of soil (A-D) existing in the Code (D.S 61).

STRESS ANALYSIS AND CHARACTERISTICS DUE TO THE SOUTH JAVA EARTHQUAKE, APRIL 10, 2021

The April 10, 2021, earthquake in the south of East Java was classified as destructive. The secondary impact of this earthquake was quite significant. Many houses collapsed, and not a few casualties. This earthquake is unique because usually, destructive earthquakes occur at shallow depths, but earthquakes with a magnitude of 6.1 are classified as medium-depth earthquakes at sea. The earthquake in the south of East Java is classified as an intraplate earthquake because it is located on the continental plate, not in the plate contact area. The question is whether the damage that occurred to the building was purely due to the magnitude of the stress released by the earthquake or whether there were other factors. This study uses seismogram data for the earthquake south of East Java on April 10, 2021, with a radius (∆) of 300-1000 recorded at MEEK, MORW, and ARMA stations in Australia. It calculates the amount of stress based on the stress drop, while the stress column determines the stress mechanism. Calculation of stress drop from the source spectrum is obtained by the deconvolution method, namely the seismogram component separation technique in the form of Source (f), Path (f), Site (f), and Instrument (f). The analysis of the observed displacement spectrum used the Nelder Mead Simplex nonlinear inversion method. Meanwhile, the Stress Columb calculation was obtained using the Columb 3.3 program from the United States Geological Survey (USGS). The result of this research is that the stress drop value is 1.69 MPa, with the type of focus mechanism being a thrust fault in the sea. The earthquake in the south of East Java was caused by rock activity in the intraplate. The value of the stress drop is more significant when compared to the subduction contact area. This area is of intraplate rock with various variations, and earthquakes are rare. This study aims to analyze the stress, both the magnitude of the stress drop and the mechanism of the column stress results, so that the stress caused by the earthquake can be known and why the earthquake in the south of East Java is destructive. The quake in Southeast Java is classified as dangerous, not because of the magnitude of the stress generated or its mechanism. The damage was due to the amplification of earthquake waves in the building. The injury occurred because most of the buildings were built on soft soil, especially in several areas in East Java, such as Lumajang, Pasuruan, Trenggalek, Probolinggo, Ponorogo, Jember, Tulunggagung, Nganjuk, Pacitan, and several urban areas, namely Blitar, Kediri, Malang, and Stone. So, there is a need for earthquake disaster mitigation, especially in densely populated areas that live on soft soil. This mitigation effort is to minimize the occurrence of casualties by building buildings according to earthquake-resistant standards and avoiding development in the regions that have the potential for amplification of earthquake waves.

A STUDY ON INTENSITY DISTRIBUTION OF CONCRETE IN STRUCTURE WITH DIFFERENT BUILDING AGES

Recently, seismic diagnosis and earthquake resistant reinforcement works of buildings built before the new earthquake resistant standards are conducted in various places. However, there is no uniformity in sampling methods, and it seems that there are occasional extreme variations in the determination of representative intensity of the building. In addition, the physical properties of structure concrete which factor of the above-mentioned variations are considered to reflect the horizontal and vertical distribution at the time of concrete placing. Therefore, this study, the core of the existing buildings to be disassembled was collected, and the distribution of physical properties of structure concrete was examined. All target buildings were reinforced concrete constructions, and cores were collected from pillars and waist walls. In addition, there are parts that were built at the time without the ready-mixed concrete plant (from 1960) and pump truck (from 1964). Experimental results of horizontal and vertical distributions of compressive intensity at the pillars and waist walls revealed that there was no greatest decrease in strength and there was not much difference between the maximum strength of the pillar and 300 mm from the vicinity of the pillar and about 300 mm from F. L. Therefore, from this study, it seems that the position of 300 mm from the pillar and F. L. is suitable for the measurement position which develops the representative intensity of the building.

EVALUACIÓN DE LA VULNERABILIDAD DEL SISTEMA DE PREVENCIÓN CONTRA INCENDIO DEL CAMPUS DE LA UNIVERSIDAD DEL QUINDIO

El estudio plantea evaluar la vulnerabilidad del sistema de protección contra incendios de las edificaciones del campus de la Universidad del Quindío, siguiendo los requerimientos establecidos en el año 2010 en los títulos J “Requerimientos de protección contra incendios en edificaciones” y K “Requisitos complementarios” de la Norma Sismo Resistente de Colombia. De acuerdo al resultado de la evaluación, se definen las alternativas de solución a emplear. En este el artículo se presenta, de igual manera, el procedimiento a realizar para evaluar el estado y la capacidad de acción que puede tener una Institución de Educación Superior según las características de sus edificaciones.

Host characteristics as factors associated with the 2015 earthquake-induced injuries in Nepal: A cross-sectional study

This study examines individual- and household-level factors associated with human injuries caused by two powerful earthquakes that hit Nepal on April 25 and May 12, 2015. A cross-sectional post-earthquake survey design was adopted to accomplish the objective of this study. Using random sampling, two of the 31 affected districts (Sindhupalchok and Lalitpur) were selected. Five study sites from each of the two districts were selected to administer questionnaire surveys. Focus group meetings and semi-structured formal and informal interviews with key informants were also used to collect relevant data. Building on previous studies, we considered nine risk factors for earthquake injuries in this study: five individual-level factors and four household-level factors. Using a goodness-of-fit chi-square test, we identified statistically significant risk factors of earthquake injuries in Nepal. Our results show that out of the nine factors, one individual-level factor – age – and two household-level factors – monthly income and type of main dwelling – were statistically significant. While long-term efforts to improve the economic conditions of those affected will reduce earthquake injuries, in the short-term, requiring seismic-resilient features in new construction and repairing damaged houses will substantially reduce earthquake injuries. Fortunately, the Nepalese Government has been ensuring that all houses are rebuilt and repaired to earthquake-resistant standards.

Earthquake Engineering – Reconnaissance and Assessment of Existing Buildings

Most existing built infrastructure, especially historical monuments, has not been designed in accordance with earthquake resistant standards. Earthquake engineering as a specific field of science and practice has only been developed over the past fifty years. Therefore, many buildings across the globe need to be inspected and to be assessed in order to determine their resistance against earthquakes based on today's knowledge. Based on safety standards and a risk assessment, the earthquake engineer provides information to the owner as to use the building in the future in order to fulfill economic as well as safety demands. This paper outlines the inspection procedure, defines the methodology of reconnaissance on site and describes the subsequent assessment of buildings from the practical point of view.

Earthquake early warning as a tool for improving society’s resilience and crisis response

Increasing vulnerability of metropolitan areas to earthquake and the very low probability level at which short term earthquake forecasting is possible make earthquake early warning methods (EEW) the main viable alternative for effective risk reduction in cities. Preventive actions, such as retrofitting and building and the diffusion of construction codes, are of course essential. They are not sufficient. A substantial proportion of the population in areas of higher earthquake hazard still reside in buildings that do not meet modern earthquake resistant standards, and cannot currently be strengthened in an economically viable manner. As demonstrated in Japan EEW has the potential of significantly contributing to reduce individual vulnerability of urban population to earthquakes. Future research on EEW should be focused on its implementation to protect lifelines, infrastructures and strategic buildings, and it should include training of administrators and people who can fully exploit the technological advantages offered by EEW systems. In particular it should foresee extensive cost-benefit analysis for each potential application, the identification and solution of legal problems (such as liability in the event of false or missed alarms), education and training, both for mitigation and response, as well as detection and processing within 1 s of the first seismic wave arrivals. Further objectives include the development of people-centred EEW, specialized IT and decision making support systems, integration of sensors, communications and decision making systems, integration into programs of eco-sustainable development, and integration with other EW systems (all hazard systems).

The Pisco (Peru) earthquake of 15 August 2007

The Mw 8.0 Pisco earthquake struck at 6.40pm local time with an epicentre offshore about 150 km south of Lima. At least 519 people were killed, and over 1,300 injured. Over 38,000 homes were destroyed and more than 100,000 were made homeless. 14 hospitals were destroyed and many other facilities damaged. The city of Pisco was worst affected with serious damage to the majority of adobe buildings. Other cities and towns nearby suffered similar damage to a lesser extent, depending on the distance from the epicentre. The capital Lima was not seriously affected, although there was some minor damage to buildings.
 Strong ground motions were felt for over two minutes. In this subduction earthquake a tsunami was generated and affected tens of kilometres of coast.
 The New Zealand Society for Earthquake Engineering Society (NZSEE) sent a 6-person reconnaissance team to Peru. The team spent three days in Lima meeting with key authorities and four days in the field observing some of the earthquake-affected area. This report describes the team’s observations and comments on the implications for earthquake engineering practice.
 Highlights of the event in the eyes of the team were:
 
 The long duration of the event – over 2 minutes of strong shaking
 The unique geotechnical context – no rainfall and sandy soils
 Significant liquefaction damage to roads and buildings
 Poor performance of adobe construction
 Generally good performance of reinforced concrete brick infill – but there were major collapses.
 Good performance of some unreinforced masonry buildings
 Widespread use of shear walls in major buildings in Lima
 Engineered structures generally performed well
 Damage to parts of Pan American Highway due to liquefaction
 Minimal damage to a major steel mill, designed to international standards
 Collapse and/or overload of telecom systems for up to four hours following the event, isolating Pisco and Ica
 Water and waste water systems and storage were seriously affected in Pisco, and significantly in Ica
 Port St Martin, serving Pisco, was seriously damaged but functional
 Coordination of overseas / international aid needs careful consideration as part of response planning.
 Management of response resources is critical.
 There were significant tsunami effects which were variable in height up to 10 metres.
 Relatively minor damage to architectural finishes and building services can render hospitals non-functional.
 Survival of industrial facilities was important in reducing social impact by saving jobs.
 The best of Peruvian earthquake engineering is international standard.
 The development of earthquake-resistant standards in schools over the last three decades has paid dividends with modern designs performing well.

Report on the damage to FRP water tanks by the Great Hanshin Earthquake

The Great Hanshin Earthquake that took place in the dawn of January 17, 1995 brought about unprecedented disasters to the Hanshin area. The size of the earthquake was recorded as a magnitude of 7.2. The acceleration observed near the epicenter was the largest in the history of earthquake observation in Japan. In this earthquake, damage that could not be explained by conventional engineering theory was observed, such as the destruction of buildings, highways and underground structures. Much damage to water tanks made of FRP were reported. However, damage to those water tanks manufactured after the revision of the earthquake resistant standards based on the revised construction standard act (1981) was much smaller than that on tanks made before the act. Damage to ceilings of many water tanks was also reported in this earthquake which were not observed previously and which therefore also characterizes this particular earthquake.