Earthquake Engineering

Reinforced Concrete (R/C) buildings with masonry infills are amongst the most common structural systems in many countries with regions of high seismicity. The infill walls are usually considered as non-structural elements and, thus, are not taken into account in analytical models. However, numerous researches have shown that they can significantly affect the seismic response of the structures. Moreover, historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. The aim of the present study is to examine the role of masonry infills on the damage response of 3D R/C buildings with various structural systems subjected to seismic sequences. For the purposes of the above investigation a comprehensive assessment is conducted using 54 3-dimensional R/C buildings with different heights, structural systems and distribution of masonry infills. The buildings are analyzed by means of nonlinear time history analysis for 80 bidirectional seismic sequences. In order to account for the influence of the incident angle on the structural response, the two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The results revealed that the influence of the successive earthquake phenomenon on the structural damage is larger for the infilled buildings compared to the bare structures. Furthermore, when buildings with masonry infills are analyzed for seismic sequences, it is of great importance to account for the orientation of the seismic motion.

This  Steel Technical Information and Product Services (Steel TIPS) report focuses on providing information to steel fabricators, detailers and structural engineers on detailing gusset plates in special concentrically braced frames. Current seismic design requirements (AISC, 2005c) for Special Concentric Braced Frames (SCBFs) permit braces,  that buckle out of plane of the gusset, to be designed as having pinned ends if a detail can be provided that allows for the expected end rotation from brace buckling. Tests by Astaneh-Asl, Goel and Hanson (1982) using hinge zone length of zero, t, 2t, and 4t showed that the length of 2t  is sufficient to accommodate the expected cyclic rotation of end of the bracing member as it undergoes cyclic buckling. The specimens with hinge zone length of less than 2t did not perform in a sufficiently ductile manner to be qualified for use in Special Concentrically Braced Frames.  Satisfying this requirement in design office or fabricating shop can be an iterative and sometimes a time-consuming process.  The main goal of this report is to provide assistance in this regard by presenting simple and closed-form equations that can be used in detailing the gusset plate without a need for iterations.  In addition, a number of suggested ”Preferred Details” of gusset plates for Special Concentrically Braced Frames are provided  that can assist design professionals as well as steel fabricators and erectors in proper and economical detailing of the gusset plate for Special Concentrically Braced Frames.

Long buildings without an expansion joints are curial for thermal loads. Looking at the current scenario it seems that there is no universally accepted design approach to accommodate building movement cased by the temperature or moisture hence there is a need to assess the thermal vulnerability over seismic loading, particularly for long buildings. This paper presents the analytical comparison between thermal and seismic response for long buildings in high seismic zone. The analytical study has been performed on five different mathematical models of the building frame with a plan aspect ratios varying from 2.0 to 3.6. Equivalent static analysis based on approximate fundamental period as per IS 1893:2002 for earthquake load and thermal analysis for selected range of temperature has been carried out by using finite element software SAP. The behaviors of these long buildings are compared for earthquake and thermal loads. Results are presented in terms of response parameters such as displacement and maximum forces for selected lateral load resisting element. The results obtained from analysis indicate that the column forces are governed by thermal load for ground story and roof displacement for thermal load will be critical after a plan aspect ratio of 3.2.

SUMMARY NEESgrid, the system integration component of the NEES project, links earthquake researchers across the US with leading-edge computing resources and research equipment, allowing collaborative teams (including remote participants) to plan, perform, and publish their experiments. The integrated tools and components made available by NEESgrid enable earthquake engineering simulation–both physical and numerical–providing an environment for researchers to develop increasingly complex, ...

Forthcoming April 2017

http://upers.kuleuven.be/en/book/9789462701052

Chapters by:
Simon Jusseret (The University of Texas at Austin, Université catholique de Louvain)
Manuel Sintubin (KU Leuven)
Jan Driessen (Université catholique de Louvain)
Susan E. Hough (U.S. Geological Survey)
James P. McCalpin (GEO-HAZ Consulting Inc.)
Christoph Grützner (RWTH Aachen University, University of Cambridge)
Thomas Wiatr (RWTH Aachen University, German Federal Agency for Cartography and Geodesy)
Charalampos Fassoulas (Natural History Museum of Crete, University of Crete)
Gerassimos A. Papadopoulos (National Observatory of Athens)
Jack Mason (RWTH Aachen University)
Klaus Reicherter (RWTH Aachen University)
Clairy Palyvou (Aristotle University of Thessaloniki)
Eleftheria Tsakanika (National Technical University of Athens)
Jeffrey S. Soles (University of North Carolina – Greensboro)
Floyd W. McCoy (University of Hawaii – Windward)
Rhonda Suka (Research Corporation of the University of Hawaii)
Colin F. Macdonald (The British School at Athens)
Tim Cunningham (Université catholique de Louvain)

... In particular, the superelastic properties of SMAs [Saadat et al., 200229. Saadat, S., Salichs, J., Noori, M., Hou, Z., Davoodi, H., Bar-on, I., Suzuki, Y. and Masuda, A. 2002. An overview of vibration and seismic applications of NiTi Shape memory alloy. ...

The expected seismic losses of structures with Rotational Friction Dampers (RFDs) are assessed by the Endurance Time (ET) method considering the optimal frictional moment of the devices. A practical method is proposed to obtain the optimal frictional moment of the dampers in multi-story structures at multiple seismic hazard levels. The ET method is used as the analytical tool in this research due to its ability to reduce the number of required analyses and providing good estimations of structural responses at various hazard levels. In order to investigate the effectiveness of the dampers, the life cycle costs of a weak steel structure equipped with optimal RFDs are compared with a standard structure with optimal RFDs and without RFDs. To this end, a comprehensive performance evaluation is performed on the structures based on FEMA P-58 methodology. The ET method is also used as a tool to assess the structural responses in the framework of this methodology. The probability of collapse, fatalities, and expected damage costs are estimated utilizing a Monte Carlo procedure considering uncertainties. Also, a cost-benefit analysis is performed to determine the payback period of investment for the additional cost of the rotational friction damping systems.

The assessment of seismic design codes has become the subject of intensive research work which revealed several weak points of the codes that originated from the limitations in predicting with acceptable precision the response of a structure under a moderate or severe earthquake. Most of the seismic design codes belong to the class of prescriptive procedures, where if certain constraints are fulfilled, the structure is considered safe. Prescriptive design procedures fail to provide acceptable levels of structural performance over its life because, in most of them, the structure is assessed using only one design earthquake. Performance-based design is a different philosophy for designing against hazards; the structure is designed to meet a number of performance objectives. The objectives of this study is to compare the initial and limit state-dependent cost of an RC building designed either to meet the provisions of the Greek national seismic design code or based on a performance-based design procedure. Two were the most important findings of this study: (i) the initial cost for an RC structure, designed to permit elastic behaviour for the response spectrum of the Greek national seismic code, is not prohibitive and (ii) that an RC structure based on the proposed performance-based design procedure lead to economical designs with respect to the total cost compared to a code conforming design. Copyright © 2006 John Wiley & Sons, Ltd.

A fully automated design methodology based on nonlinear response history analysis is proposed for the optimum seismic design of reinforced concrete (RC) structures. The conventional trial-and-error process is replaced by a structural optimization algorithm that serves as a search engine capable of locating the most efficient design in terms of cost and performance. Two variations of the proposed design methodology are introduced. The first approach treats the optimum design problem in a deterministic manner, while in the second variation the optimum design is sought in the framework of a reliability-based optimization problem. The reliability-based approach seems to be a more rational procedure since more meaningful design criteria that correlate better with the performance-based design concept can be adopted. Thus, the practice of using the mean annual frequency of a limit-state being exceeded to assess the candidate designs is compared with the use of deterministic criteria. Both ...

Smoothed gridded seismicity is an analysis model in seismicity that allows for the obtaining of a rate based on the b-value and the same magnitude range. The data study has been collected and analyzed from a background source gath-ered by PusGen, referred to as the PusGen catalogue, with approximately 70 thousand data points. Two software pro-grams (i.e. USGS PSHA and OpenQuake) were utilized in this study, and both programs have been proven as reliable in the creation of the 2017 Indonesia Earthquake Hazard Map. The final steps are to compare the acceleration map results with the Kalimantan Island land-use map and to analyze suitability development planning against potential hazards and earthquake risks. The results stated that: (1) acceleration due to the shallow background earthquake for the Kalimantan region, range from 0.00-0.25g (using USGS PSHA) and 0.0-0.4g (using OpenQuake); (2) meanwhile, based on the deep background earthquake source, the maximum accelerations that occur are 0.15g and 0.25g when using USGS PSHA and OpenQuake, respectively; (3) the utilized of land-use for the current and future years is in line with the results of the acceleration simulation. The study recommends to take into account the seismic aspects in new planning of the capital city, mining and residential areas in order to reduce the existing risks.

Interaction between pile and soil is one the most important cases in Geotechnical engineering and also related sciences. Many of scholars have already explored this issue and examined various aspects of the behavior of piles under influence of different loads. Due to increasing of Micro piles in the last decade and Liquefaction dangerous due to earthquake, in this study micro pile bearing capacity is considered. Numerically, Micro piles behavior for reinforcing of saturated soil is studied. 3-D dynamic finite element method for analyzing of saturated porous condition based on the Biot equations has been used. Governing equations consist of soil displacement and water relative displacement as initial variable are supposed. Cyclic Elasto-plastic behavior of soil under earthquake loading is simulated by using a generalized plasticity theory composing of a yield surface together with non-associated flow rule. In this study, effects of model with one micro pile, without micro pile and model with micro piles group are investigated on the liquefaction potential.

There is a huge inventory of existing vulnerable buildings and only a little research has been done concerning the economic side of their retrofit. The study presented in this paper aims to show how further issues, for example costs, can be taken into account from the early stages of the rehabilitation project, like the building survey, through collecting and organising the data, to building a cost assessment. It describes a way from the building survey, identifying the loadbearing structure through to cost assessment for rehabilitation works. The core idea is that each structure can be divided into units called "retrofit elements", for which both seismic performance and costs are easier to assess. There is literature about typical performance curves for selected retrofit elements, like columns or frames. The conclusions of a study regarding the cost-effectiveness study are being used for the integration purposes.

Resilience is a performance measure representing both the capability of a system to survive a disruptive event and the ability of rapidly restoring the operational status recovering the initial capacity. However, literature is lacking about methods allowing to compute resilience of process plants from a technical point of view. In fact, in the process industry the scarce literature about resilience mainly focused on organisational issues. In order to contribute to fill this gap a methodology has been developed to estimate resilience in case of Na-Tech events for process plants. The methodology provides a direct estimation of capacity loss after the disruptive event, and the time trend of recovery as well as the related economic loss. The model can be applied both in deterministic and probabilistic manner and is generalizable to any kind of Na-Tech hazard. However, in this paper specific reference is made to seismic hazard. In order to show the capabilities of the methodology a case study is also described referring to a Nitric Acid plant. Results show the predictive capabilities of this approach and the usefulness as a decision making tool for facility planners and emergency managers in the process industry.

— Designing an efficient Distributed Database System (DDBS) is considered as one of the most challenging problems because of multiple interdependent factors which are affecting its performance. Allocation and fragmentation are two processes which their efficiency and correctness influence the performance of DDBS. Therefore, efficient data fragmentation and allocation of fragments across the network sites are considered as an important research area in distributed database design. In this paper presents an approach which simultaneously fragments data vertically and allocates the fragments to appropriate sites across the network. Bond Energy Algorithm (BEA) is applied with a better affinity measure that improves the generated clusters of attributes.

"This paper presents a new technique for modelling the dynamic response of uplifting rigid structures subjected to base excitation. The proposed technique exploits the use of a two-spring foundation, and subsequently an equivalent single-degree-of-freedom procedure is established to model the dynamics of the system. A set of simplified closed-form expressions have been developed to estimate the system’s restoring force-displacement characteristics. The simplified expressions only require details of the system geometry and are shown to predict the nonlinear force-displacement characteristics of a rocking structure as closely as those determined from a complicated pushover analysis.
This paper presents two additional numerical examples to demonstrate the use of the proposed technique to simulate the displacement time-histories of a prototype structure under free-vibration-decay or when subjected to earthquake excitations."

Researches in past indicates that response of soil under seismic forces influences the seismic response of the building. Soil structure interaction (SSI) has a significant impact on dynamic response of structure, which may lead to unexpected seismic response or failure of structure. Due to the urbanization multi-storey building with underground storey for parking space and storage are very common in practice. Failures of these types of buildings during earthquake show the significance of soil structure interaction effect on underground storey buildings. Aim of this paper is to study and understand the effect of underground storey on structure considering soil structure interaction during earthquake. In this study seismic response of G+9 fix base and underground storey buildings are compared. Response Spectrum method of dynamic analysis has been used to analyze the building for seismic zone V according to IS 1893:2002 in FEM software CSI SAP2000, Version14. Elastic continuum approach is use to idealize the soil. Two different types of soils SW and ML categorised under hard, low stiff respectively in IS 1893(Part I):2002 are used in this research. Design forces in terms of storey shear is calculated for underground storey building and results are compared with the conventional fix base building. The study reveals that on considering SSI, there is an increase in lateral time period of the building and redistribution of storey shear forces in flexible base model as compared to fixed base model.

This paper assesses the seismic performance of typical reinforced concrete (RC) existing framed
structures designed for gravity loads only. The sample two-storey structural system exhibits high
vulnerability, i.e. low lateral resistance and limited translation ductility; hence an effective strategy
scheme for seismic retrofitting was deemed necessary. Such a scheme comprises buckling restrained
braces (BRBs) placed along the perimeter frames of the multi-storey building. The adopted design
approach assumes that the global response of the inelastic framed structure is the sum of the elastic
frame (primary system) and the system comprising perimeter diagonal braces (secondary system); the
latter braces absorb and dissipate a large amount of hysteretic energy under earthquake ground
motions. Comprehensive nonlinear static (pushover) and dynamic (response history) analyses were
carried out for both the as-built and retrofitted structures to investigate the efficiency of the adopted
intervention strategy. A set of seven code-compliant natural earthquake records was selected and
employed to perform inelastic response history analyses at serviceability (operational and damageability
limit states, OLS and DLS) and ultimate limit states (life safety and collapse prevention limit
states, LSLS and CPLS). Both global and local lateral displacements are notably reduced after the seismic
retrofit of the existing system. In the as-built structure, the damage is primarily concentrated at the
second floor (storey mechanism); the computed interstorey drifts are 2.43% at CPLS and 1.92% at LSLS
for modal distribution of lateral forces. Conversely, for the retrofitted system, the estimated values of
interstorey drifts (d/h) are halved; the maximum d/h are 0.84% at CPLS (along the Y-direction) and 0.65%
at LSLS (yet along the Y-direction). The values of the global overstrength O vary between 2.14 and 2.54
for the retrofitted structure; similarly, the translation ductility mD-values range between 2.07 and 2.36.
The response factor (R- or q-factor) is on average equal to 5.0. It is also found that, for the braced frame,
under moderate-to-high magnitude earthquakes, the average period elongation is about 30%, while for
the existing building the elongation is negligible (lower than 5%). The inelastic response of the existing
structure is extremely limited. Conversely, BRBs are effective to enhance the ductility and energy
dissipation of the sample as-built structural system. Extensive nonlinear dynamic analyses showed that
more than 60% of input seismic energy is dissipated by the BRBs at ultimate limit states. The estimated
maximum axial ductility of the braces is about 10; the latter value of translation ductility is compliant
with BRBs available on the market. At DLS, the latter devices exhibit an elastic behaviour. It can thus be
concluded that, under moderate and high magnitude earthquakes, the damage is concentrated in the
added dampers and the response of the existing RC framed structure (bare frame) is chiefly elastic

 Abstract— Distribution design involves making decisions on the fragmentation and allocation of data across the sites of a computer network. Multiple vertical splitting is the process of subdividing the attributes of a relation to generate fragments. In this paper, we propose an analysis for multiple vertical splitting algorithm using Slop Based Partitioning Algorithm (SBPA). This approach starts from the attribute affinity matrix and generates initial clusters based on the affinity values between attributes. Then, it uses the database according to optimal splitting solution to produce final groups that will represent the fragments. Then we analyzed these fragments according to their contribution level. The result is generated that shows how to find optimal solutions.

This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) infill walls. Two applications are conducted using structural systems of RC frames with URM infill walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM infill wall. Copyright © 2009 John Wiley & Sons, Ltd.

DBELA is a Displacement-Based Earthquake Loss Assessment methodology for urban areas which relates the displacement capacity of the building stock to the displacement demand from earthquake scenarios. The building stock is modeled as a random population of building classes with varying geometrical and material properties. The period of vibration of each building in the random population is calculated using a simplified equation based on the height of the building and building type, while the displacement capacity at different limit states is predicted using simple equations which are a function of the randomly simulated geometrical and material properties. The displacement capacity of each building is then compared to the displacement demand obtained from an over-damped displacement spectrum, using its period of vibration; the proportion of buildings where damage exceeds each specified threshold value can thus be estimated. DBELA has been applied using the Turkish building stock following the collection of a large database of structural characteristics of buildings from the northern Marmara region. The probabilistic distributions for each of the structural characteristics (e.g., story height, steel properties, etc.) have been defined using the aforementioned database. The methodology has then been applied to predict preliminary damage distributions and social losses for the Istanbul Metropolitan Municipality for a Mw 7.5 scenario earthquake.

Abstract

Many natural disasters that have occurred in recent years have caused loss of property as well as deaths. The earthquakes that have occurred in recent years have resulted in considerable loss of property and life and have necessitated much rapid construction of houses. On the other hand, the large housing deficit that emerged after the earthquake and called for an immediate solution resulted in housing that were constructed without considering factors such as socio-cultural data, user needs, habits and spatial quality. The aim of this research is to analyze the degree of satisfaction with the after-earthquake houses and quality as a factor affecting user satisfaction. As part
of the study, a questionnaire was conducted in a mass housing area with 858 units in Yalova, Soğucak, which was realized by The Ministry of Public Works and Settlement after the 1999 Marmara earthquakes. The results of the questionnaire are evaluated on SPSS (Statistical Package for Social Sciences) using one sample t-test, Mann-Whitney U test, factor analysis and chi-square test. The results of this study have important
implications for satisfaction with after-earthquake houses and the attitudes of the users.