Response Spectra

This paper compares EuroCode 8 (EC8) and the Japanese seismic design code (BCJ) for steel moment frames and braced frames. Soil classification, magnitude and shape of unreduced elastic response spectra, distribution of seismic shear along the height, member ductility requirements, and behavior factor are compared. It was found that the two codes are relatively similar except for the seismic force

Iran as one of the countries located on the Alpine-Himalayan seismic belt has recently
experienced a few number of catastrophic earthquakes. A well-known index of how buildings are affected
by earthquakes is through assessment of probable Peak Ground Acceleration (PGA) and structures’ response
spectra. In this research, active faults around Kerman and Birjand, two major cities in eastern parts of Iran,
have been considered. Seismic catalogues are gathered to categorize effects of surrounding faults on
seismicity of the region. These catalogues were further refined with respect to time and space based on
Knopoff-Gardner algorithm in order to increase statistical independency of events. Probabilistic Seismic
Hazard Analysis (PSHA) has been estimated for each of cities regarding 50, 100, 200 and 500 years of
structures’ effective life-span. These results subsequently have been compared with Deterministic Seismic
Hazard Analysis (DSHA). It has been observed that DSHA not necessarily suggests upper bound of PSHA
results. Furthermore, based on spectral Ground Motion Prediction Equations (GMPEs), Uniform Hazard
Spectra (UHS) and spectral acceleration were provided for 2% and 10% levels of probability of exceedance.
The results show that increasing source-to-site distance leads to spectral acceleration reduction regarding
each fault. In addition, the spectral acceleration rate of variation would increase if the source-to-site distance
decreases.

CASE STUDIES FOR SPECIAL INVESTIGATIONS

Lateral Loads

                      Seismic
                                      Site specific response spectra

                      Wind
                                        Wind tunnel report and TLD

This chapter presents research works carried out in developing the latest spectral hazard maps proposed as input for revision of Indonesian Earthquake Resistant Building Code, the SNI 03-1726-2002. Improvement in seismic hazard analysis and careful inclusion of recent seismic records were augmented. Seismic sources were modeled by background, fault, and subduction zones considering truncated exponential model, pure characteristic model or both. Several well-known attenuation functions were selected including the Next Generation Attenuation (NGA). Maps of Peak Ground Acceleration (PGA) and Spectral Response Acceleration (SRA) for 0.2 s (short periods) and 1.0-s period for 2% probability of exceedance in 50 years were developed using PSHA. Additional geotechnical and tsunami hazard assessment researchs for Banda Aceh city, the capital of Aceh Province were also submitted. The results of site response analysis and liquefaction study at several points were utilized to generate contours of acceleration, amplification factor, design response spectra, and potential of liquefaction for Banda Aceh. The tsunami hazard study was conducted using mathematical simulation and modeling leading to estimate the potential tsunami that may occur in the future which covers tsunami inundation, run-up, and developing tsunami zonation map. The output of geotechnical and tsunami hazard assessment was then overlayed on top of the land use city planning in a Geographical Information Systems (GIS) database and used as criteria for tsunami warning system, an input in developing land use management for Banda Aceh, and enriching the basic regulation for new infrastructures and local building codes.

The transmission line towers are one of the important life line structures in the distribution of power from the source to the various places for several purposes. The predominant external loads which act on these towers are wind and earthquake loads. In this present study tower is analyzed using Indian Standards IS: 875:1987(Wind Load), IS: 802:1995(Structural steel), IS:1893:2002 (Earthquake) and dynamic analysis of tower has been performed considering ground motion of 2001 Bhuj Earthquake (India). The dynamic analysis was performed considering a tower system consisting two towers spaced 800m apart and 35m height each. This analysis has been performed using numerical time stepping finite difference method which is central difference method were employed by a developed MATLAB program to get the normalized ground motion parameters includes acceleration, frequency, velocity which are important in designing the tower. The tower is analyzed using response spectrum analysis.

Rotational and vertical components of ground motion are almost always ignored in design or in the assessment of structures despite the fact that vertical motion can be twice as much as the horizontal motion and may exceed 2g level, and rotational excitation may reach few degrees in the proximity of fault rupture. Coupling of different components of ground excitation may

The effects of far distant earthquakes felt in regions with low and moderate seismicity has increased markedly over the last decade. Henceforth fragility curves in this study are to indicate whether buildings are safe to enter or not after an earthquake event occurring more than 300km away. The probability of light, moderate and severe damage states occurring on two and four storey reinforced concrete buildings up to a peak ground acceleration of 0.2g were predicted. The building models were constructed using finite element software based on eight node brick elements with three degrees of freedom at each node. The analysis was carried out using a dynamic response spectrum to calculate the peak inter-storey drift ratios. For the development of fragility curves, the results were collated following a log-normal mean distribution. The results showed that light damage is likely to occur with a probability of over 10% within a 50 year period, while the existing record is unlikely to cause structural damage. The fragility curves were comparable to those for RC moment resisting frames obtained by (Rossetto and Elnashai 2003) at a lower drift limit, with approximately 2% of inter-storey drift ratio.

http://www.sciencedirect.com/science/article/pii/S1877705811013531

Following the April 6th, 2009 Abruzzo mainshock, the Italian Civil Protection Department promoted a multidisciplinary study aimed at developing seismic microzonation maps for post-earthquake reconstruction planning. In the framework of this project, a Working Group, including the authors, was assembled to carry out a microzonation study on six villages located in the Middle Aterno valley. This paper focuses on the villages of Castelnuovo and Poggio Picenze, which experienced MCS intensity values of IX–X and VIII–IX, respectively. 1D and 2D linear equivalent site response analyses were carried out on representative geological cross-sections through the damaged centres and the expansion zones. The subsoil models resulting from geological, geotechnical and geophysical investigations were calibrated by comparing numerical amplification functions, in the linear range, with horizontal-to-vertical spectral ratio derived from both aftershocks and noise recordings. The input motions adopted for the analyses were five artificial accelerograms compatible with three response spectra obtained from the Italian seismic code, as well as from ad hoc probabilistic and deterministic studies. The results were expressed in the form of horizontal profiles of amplification factors in terms of peak ground acceleration, FPGA, as well as of the Housner intensity, FH, in two different range of periods; this latter parameter was shown to be almost independent of the input motion and allowed to express the dependency of site amplification on the frequency range. The amplification factors computed along the representative geological sections were finally extended with a rational procedure to the surrounding areas to draw Grade-3 microzonation maps.

The selection of specific elastic response spectra according to soil categories is the easiest way to account for site effects in engineering projects and general-purpose hazard maps. Most of the international seismic codes make use of the average shear wave velocity of the upper 30 m (Vs,30) to discriminate soil categories, although some doubts arose about the capability of Vs,30 to predict actual soil amplification. In this work we propose two soil classifications in which the soil fundamental frequency (f0) becomes either an alternative or a complement to Vs,30. The performance of the derived categorizations is achieved through the estimation of the standard deviation associated to ground motion prediction equations of acceleration response spectra, considering recordings extracted from the Italian strong motion data base. The results indicate that there is a significant reduction of the standard deviation when the classification is based on the couple of variables Vs,30–f0, although a classification based of the single f0 also leads to satisfactory results, comparable with those obtained assuming a classification scheme based on Vs,30.

Earthquake loss estimation studies require predictions to be made of the proportion of a building class falling within discrete damage bands from a specified earthquake demand. These predictions should be made using methods that incorporate both computational efficiency and accuracy such that studies on regional or national levels can be effectively carried out, even when the triggering of multiple earthquake scenarios, as opposed to the use of probabilistic hazard maps and uniform hazard spectra, is employed to realistically assess seismic demand and its consequences on the built environment. Earthquake actions should be represented by a parameter that shows good correlation to damage and that accounts for the relationship between the frequency content of the ground motion and the fundamental period of the building; hence recent proposals to use displacement response spectra. A rational method is proposed herein that defines the capacity of a building class by relating its deformation potential to its fundamental period of vibration at different limit states and comparing this with a displacement response spectrum. The uncertainty in the geometrical, material and limit state properties of a building class is considered and the first-order reliability method, FORM, is used to produce an approximate joint probability density function (JPDF) of displacement capacity and period. The JPDF of capacity may be used in conjunction with the lognormal cumulative distribution function of demand in the classical reliability formula to calculate the probability of failing a given limit state. Vulnerability curves may be produced which, although not directly used in the methodology, serve to illustrate the conceptual soundness of the method and make comparisons with other methods.

یکی از عوامل تاثیر گذار بر روی محتویات طیف پاسخ زلزله، اثرات نزدیک گسل مانند ارتعاشات ضربه ای یا پالسی می
باشد. مطالعات پیشین نشان داده است که افزایش پریود پالس حرکت زمین به پریود طبیعی سازه و همچنین افزایش
نسبت شتاب زمین به مقاومت تسلیم سازه، موجب افزایش پاسخ غیر خطی و خسارت بالا به سازه می شود پس لزوم
تحقیق و مقایسه چنین اثراتی ضروری است. هدف از این مقاله، مقایسه طیف پاسخ ساختگاه مطابق با چهار منطقه آیین
نامه ایران در حوزه های نزدیک و دور از گسل با چند طیف طرح استاندارد معتبر از جمله ایران می باشد. نتایج نشان
0 ثانیه اثرات ناشی از جهت داری باعث افزایش مولفه افقی عمود بر گسل نسبت / دادند در محدوده دوره تناوب کمتر از 5
به مولفه افقی موازی با امتداد گسل شده است. در نتیجه اثرات نزدیک گسل شدیدا وابسته به شرایط ساختگاه نظیر نوع
گسل و مکانیزم شکست آن، فاصله ساختگاه از گسل در ناحیه جهت داری پیش سوی، فعالیت منبع لرزه زا، نوع خاک
ساختگاه و بزرگی زلزله می باشد.