Earthquake-resistant Structures Research Articles

Critical Review on Base Isolation: An Earthquake-Resistant Technique

Every structure is subjected to some sort of dynamic loading during its entire life span. Dynamic loading in structure systems may result from a wide variety of sources such as wind, waterways, earthquake, blasts and others. Earthquake forces are the most devastating one among dynamic loadings. A disruptive disturbance that causes collision of tectonic plates in Earth's crust and results in shaking of the earth surface is known as earthquake. These forces last only for a fraction of a minute but will often cause great loss of life and property. Therefore, it is time requirement to make earthquake-resistant buildings for providing safety to buildings. Consequently, attempts have been made to make earthquake-resistant structures all over the world. Base isolation is an effective method for improving the seismic performance of structures and to counteract the detrimental component of seismic forces. This method consists of secerning of building from horizontal ground motion by placing horizontally discrete isolators at the base level of structure. In this paper, the different types of base isolation systems and bearings used for base isolation technique are discussed.

Surface wave surveying for near-surface site characterization in the East San Francisco Bay Area, California

Seismic surface wave methods are effective tools for estimating S-wave velocity in urban areas for near-surface site characterization and geologic hazard assessment. A surface wave survey can provide quantitative site-specific measurement of physical properties needed for the design of earthquake-resistant structures. We successfully used a combined active and passive seismic surface wave method to estimate the S-wave velocity in the upper 30 m at sites with a range of geologic conditions. At five of the six sites, multichannel analysis of surface waves (MASW) and microtremor array method (MAM) methods were used. The MAM method could not be used at one site due to insufficient ambient noise. Data from the active method (MASW) contained higher frequencies that contributed to higher resolution of the near-surface zone, whereas passive data (MAM) contained lower frequencies that provided deeper penetration. Phase velocities from the two methods were in good agreement in the frequency range where they overlapped. Surface wave dispersion curves from the two methods were used to prepare an initial velocity model, and a nonlinear inversion was performed to obtain an improved velocity-depth profile. The use of a multimethod data set provided greater confidence in velocity measurements. The six sites of this study may be classified as belonging to two main groups based on S-wave velocities and geologic materials. Two sites are located in the East Bay Hills on Mesozoic bedrock, and four sites are located on Holocene sedimentary units. The highest [Formula: see text] was [Formula: see text] (class C), at a site with fractured and weathered bedrock exposed in a geotechnical trench at 1–2 m depth. The four sites on Holocene sedimentary units have [Formula: see text] values ranging from 207 to [Formula: see text] (class D).

Seismic performance of three-storey full-scale sub-standard reinforced concrete buildings

Two three-story full-scale sub-standard reinforced concrete buildings were tested under self-weight and reversed cyclic lateral displacements to examine their behavior during earthquakes. While one of these buildings was a part of an actual existing building (TB1) built in the beginning of 1990’s in Istanbul, the other was constructed by the authors as a representative building (TB2) that reflects the most common structural deficiencies of existing building stock in Turkey. Both buildings were constructed with plain bars, low strength concrete and inadequate lateral reinforcement. The differences between these buildings were axial load levels of first story columns, expected location of major structural damages (weak beam–strong column for TB1 and strong beam–weak column for TB2) and connection details of longitudinal bars in columns at the foundation–column interface (continuous for TB1 and lap-spliced with 180° hooks for TB2). Both buildings were pushed and pulled at increasing displacement amplitudes up to near collapse well beyond the life safety performance level. While TB1 was damaged significantly at 1.5 % inter-story drift ratio, TB2 reached near collapse damage at 4.0 % inter-story drift ratio. In this paper, details and test results of these two sub-standard buildings are presented. In addition, the available nonlinear modeling techniques and performance predictions of the Turkish Seismic Design Code (Specification for the buildings to be constructed in disaster areas. Ministry of Public Works and Settlement, Ankara, 2007), ASCE 41-13 (Seismic rehabilitation of existing buildings, ASCE/SEI 41-13. ASCE, Reston, 2014) and Eurocode 8-3 (Eurocode 8: Design of structures for earthquake resistance. Part 3: Assessment and retrofitting of buildings. Comite Europeen de Normalisation, Bruxelles, 2005) are compared with the experimental results.

Dissipative devices for earthquake resistant composite steel structures: bolted versus welded solution

This paper investigates and compares the seismic performance of two types of innovative repairable fuse devices for earthquake resistant composite steel frames through experimental tests and numerical analyses. The fuses are energy dissipating devices consisting of steel plates that can be welded or bolted to the beam web and bottom flange. The numerical analyses performed in this study are based on the results of experimental tests carried out on beam-to-column sub-assemblages equipped with both the types of fuse devices. The main differences in terms of hysteretic behavior and failure modes of the fuses are identified through the experimental campaign. Detailed three-dimensional finite element models of the beam-to-column sub-assemblages are then created to provide a deeper insight into both the response and the effectiveness of the two investigated devices. On the basis of the results of both the experimental tests and numerical analyses, simplified models of different types of fuses are developed in order to study the effects of bolted and welded devices on the seismic response of composite steel frames. The results are then extended to the case of three-dimensional building structures with different number of storeys. The experimental and numerical investigations prove the effectiveness of the fuses and highlight the main differences between the two possible solutions.

An experimental study on FRC infilled steel tubular columns under eccentric loading

Concrete filled Steel tubular columns have become more popular as the requirements on the performance of steel structures increased as in case of tall buildings all over the world. These types of columns offer a number of advantages attaining economy in the construction and have been used in variety of applications. Because of their excellent ductility these have been used in earthquake resistant structures. This paper presents an experimental study on the behavior of both plain and fiber reinforced concrete filled slender steel tubular columns eccentrically loaded in compression to failure. The composite columns have different lengths varied from 11D to 28D and diameter to thickness ratio of the steel tube is 38. The column strength, load-strain relationships, load-mid height deflection relationships and failure modes were measured from the tests. Companion tests on six numbers of similar empty steel tubes were also undertaken to highlight the beneficial effects of composite column. The study has shown that fiber reinforced concrete filled steel tubular slender columns offer a significant increase in the column strength and ductility compared with plain concrete filled steel tubular slender columns.

PDEM-Based Perspective to Probabilistic Seismic Response Analysis and Design of Earthquake-Resistant Engineering Structures

AbstractA perspective based on the probability density evolution method (PDEM) to the probabilistic seismic response analysis and design of earthquake-resistant engineering structures is provided in this paper. The development of characterization of randomness in seismic ground motions and nonlinear seismic dynamic response analysis of engineering structures are first reviewed and found to be almost independent, which hinders rapid adoption of refined methods for seismic design. The approaches for stochastic dynamics, which is expected to bridge the above gap, in earthquake engineering are revisited, which results in the statement that more physically based methodology is in urgent need for nonlinear stochastic dynamic response analysis of structures. This is the role that the PDEM will play, and thus the theoretical basis and some new advances of PDEM, including the ensemble evolution form of the generalized density evolution equation, ensemble evolution–based dimension reduction of Fokker-Planck-Kolmogo...

Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations.

The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

New methods to improve the assessment of shear wave velocities and seismic hazard parameters in Jeddah city, western Saudi Arabia

Seventy-five geotechnical boreholes were drilled in Jeddah city to identify the soil characteristics and calculate the shear wave velocity. The depth of boreholes extends up to 40 m in some sites, where the standard penetration test (SPT) was assigned at each 1.5 m depth interval. The groundwater table fluctuated between 0.5 and 9 m below the ground level. In addition, the multichannel analysis of surface waves (MASW) method was applied at the same borehole locations to estimate the shear wave velocity of the subsurface layers. 1D shear velocity profiles were processed using SeisImager software. The calculated shear wave velocity at the mid-point of each surveying line was compared with that of the borehole because the mid-point of the surveying line coincides with the borehole location. In addition, horizontal–vertical-spectral ratio inversion (INV_HVSR) of microtremor measurements recorded at the borehole locations represents a third method to estimate the shear wave velocity of subsurface layers. Results of these three methods are then compared and, finally, the average shear wave velocity values, up to a depth of 30 m, were assessed for Jeddah city. According to Vs (30) values, the soil classes for Jeddah city can be classified into three classes as “site class D,” “site class C,” and “site class B,” according to the National Earthquake Hazard Reduction Program (NEHRP). These results should be added to the Saudi Building Code (SBC) to improve the requirements for the design of earthquake-resistant structures in Jeddah city.

ОБ ОСОБЕННОСТЯХ МЕТОДОЛОГИИ НЕЛИНЕЙНОГО СТАТИЧЕСКОГО АНАЛИЗА И ЕГО СОГЛАСОВАННОСТИ С БАЗОВОЙ НОРМАТИВНОЙ МЕТОДИКОЙ РАСЧЁТА ЗДАНИЙ И СООРУЖЕНИЙ НА ДЕЙСТВИЕ СЕЙСМИЧЕСКИХ СИЛ

The nonlinear static analysis should be clear for engineers in case of its integration into building design in seismic regions of Russia. Basic assumptions and advantages of the analysis, as well as its coordiantion with the linear spectral calculation method are considered by the author. The examples of structures calculated according to NSA, in particular in SAP2000 software are given. Keywords: earthquake-resistant structures; diagram method of calculation; patterns of seismic force distribution; performance-based plastic design (PBD) method.

The Earthquake Ground Motion and Response Spectra Design for Sleman, Yogyakarta, Indonesia with Probabilistic Seismic Hazard Analysis and Spectral Matching in Time Domain

Earthquake acceleration time history and response spectra design are needed as basis to determine the earthquake loading that can be used to design and assess the tall building and other structures. The acceleration time history and response spectra design for certain site can be acquired using the seismic hazard analysis, amplification of ground motion quantity, and spectral matching in time domain. The result is the artificial acceleration time history for a site in Sleman District, Yogyakarta, Indonesia. That time history can be utilized as a basis to design and assess the earthquake resistant building structure in the district area.

Features of the Masonry Structure Calculation with Vertical Ring Beams based on the European Standards

The design of masonry structures should remain a combination of traditional and modern knowledge. The Eurocodes in the field of the design of earthquake-resistant masonry structures, carry mostly acceptable and expected recommendations and requirements. This paper shows that they contain less acceptable principles, which require further experimental and analytical studies. Particularly it should be noted that Eurocode knows only a shearing mechanism by the horizontal coupling, although during the seismic load, the fracture usually occurs due to exceeding the main tensile stress, which manifests by opening diagonal cracks. The mechanism of the horizontal shearing by Eurocode is treated as critical for the seismic resistance of most masonry buildings, thus the masonry structure is attributed as sufficiently secure, although its actual seismic resistance would be far below from the required.

Continuing Development of Seismic Actions Design Standard and Implications to Engineering and Architectural Practices in Malaysia

This paper presents the work of the Technical Committee on Earthquake led by The Institution of Engineers Malaysia (IEM) and sanctioned by the Department of Standards Malaysia (DSM). From the Aceh earthquake event in 2004 to the most recent impact earthquake in Ranau, Sabah, it has been shown that earthquakes are a concern to stakeholders in the local construction industry. And the work of the Technical Committee has been finalized by the completion of the Draft National Annex on Eurocode 8 Design of structures for earthquake resistance, in order to address the needs of the nation. The need for earthquake standards in Malaysia was explained in detail, and the approach adopted was highlighted with emphasis on tackling both distance and local earthquakes, in Peninsular Malaysia as well as Sabah and Sarawak. Ductility is the main consideration in many earthquakes-resistant designed structures, and this has to go hand in hand with the types of configurations of structures to be proposed by architects and engineers.

ACCOUNTING OF DAMPING IN THE EVALUATION AND SEISMIC STABILITY TASKS OF BUILDINGS AND STRUCTURES

It is proved that for the majority of building structures characterized by different damping elements. The goal of constructing matrix hysteretic damping that takes into account the internal friction in the material. The study is based on generalized hypothesis of E. S. Sorokin on the proportionality of the matrices of damping and stiffness elements of the structure. The methods of accounting for damping in the evaluation of the earthquake resistance of structures. The exact and approximate methods of decomposition of the motion equations for the mode shapes are considered. It is established that the empirical criterion of the approximate method applicability of accounting for damping and its refinement on the basis of the initial approximation can serve as the correlation coefficients of waveforms. It is shown that for non-proportional damping it is possible to approximate the decomposition of movements according to oscillations forms of non-damped system, if the forms are weakly correlated.

Proposal Study of Vibration Model with Seismic Control Damper Using on Education of Earthquake-resistant Structure

Proposal Study of Vibration Model with Seismic Control Damper Using on Education of Earthquake-resistant Structure

Estudo da influência da configuração estrutural na resposta sísmica de uma estrutura de concreto armado

Resumo Os recentes aumentos dos registros de abalos sísmicos no Brasil impulsionaram a publicação da NBR 15421:2006 [1] - Projeto de Estruturas Resistentes a Sismos - na qual são definidas as cargas sísmicas a serem consideradas no projeto em função da capacidade de dissipação de energia no regime inelástico das estruturas e da sismicidade do território brasileiro. Algumas edificações construídas antes da publicação dessa norma não foram projetadas para resistir a ações sísmicas aumentando a sua fragilidade e vulnerabilidade para terremotos de qualquer intensidade. Observa-se ainda que alguns desses edifícios foram projetados e construídos com distribuições irregulares de massa, rigidez ou resistência ao longo da sua altura que podem levar a um desempenho sísmico inadequado. Assim, torna-se essencial para os engenheiros e projetistas uma melhor compreensão dos efeitos dos abalos sísmicos no comportamento sísmico de edificações, especialmente aquelas com diversas irregularidades. Por simplicidade, utiliza-se neste trabalho o termo "estruturas irregulares" para referenciar estruturas como as descritas. Nesse sentido, o objetivo deste trabalho é avaliar o comportamento sísmico de uma estrutura de concreto armado de oito pavimentos e com diversas irregularidades introduzidas na planta da mesma, a fim de verificar a influência dessas irregularidades na perda da capacidade de resistir cargas laterais e dissipação de energia, as quais são calculadas utilizando o método dinâmico espectral e uma análise pushover, procedimentos descritos nas normas NBR15421:2006 [1] e na norma americana FEMA 356 [2]. Do mesmo modo, calcula-se o desempenho sísmico dos modelos usando o método do espectro de capacidade definido na norma ATC-40 [3]. Todos os resultados são comparados com os obtidos para uma estrutura totalmente regular chamada de caso base ou de referência, com o intuito de visualizar as diversas mudanças provocadas pelas irregularidades. O estudo proposto é realizado de forma numérica e as simulações são feitas no programa CSI ETABS(r) Nonlinear v9.5 [4]. Os resultados mostram que a capacidade da estrutura dependerá da plasticidade de seus elementos para não colapsar e do detalhamento adequado para garantir o bom funcionamento do sistema resistente.

Effect of microstructure and texture on the impact transition behaviour of thermo-mechanically treated reinforcement steel bars

In order to develop earthquake resistant or blast resistant structures for freezing environmental condition, it is necessary to evaluate the impact toughness and impact transition behaviour of thermo-mechanically treated (TMT) reinforcement steel bars. Considering the difficulty in preparing standard geometry Charpy V-notch specimens from the TMT rebar, a new specimen design, on semi-circular cross-section, is proposed in the present study for the impact testing of rebars. Tensile testing and impact toughness testing have been carried out on the TMT rebar samples of different diameters (10–16mm) to study the processing-microstructure-mechanical property relationship. Among the investigated rebars, higher section rebar (16mm) showed the best combination of strength, ductility and impact toughness possibly due to the higher tempered martensite rim fraction and the presence of degenerated pearlite and lower bainite at the core region of that rebar. Large fraction of high-angle boundaries and the presence of gamma-fibre texture could have contributed to the lowest ductile–brittle transition temperature (DBTT) in 12mm rebar. Impact toughness can also be influenced by the residual stress distribution inside the rebars.

Simple Method to Develop Seismic Microzonation Maps for Cities in Northern Haiti and Elsewhere

Many developing nations are situated in zones of high seismicity where earthquakes can lead to widespread property loss and loss of life. Similar-sized earthquakes are not nearly as devastating in developed nations because of access to state-of-practice engineering methods. Earthquake engineering to reduce property loss and loss of life includes geotechnical engineering to predict likely amounts of ground shaking. Herein, a simple geotechnical approach was implemented in four cities in northern Haiti, including Port-de-Paix, Cap-Haitien, Fort Liberte, and Ouanaminthe based. The approach was based on the use of a simple geophysical technique and the application of International Building Code criteria to calculate design levels of ground shaking. The Spectral-Analysis-of-Surface-Waves (SASW) method is a geophysical technique that was employed in the four test cities during a five-day test period utilizing three workers and a backpack full of equipment. As a result of this investigation, microzonation maps depicting design ground surface shaking parameters were rapidly and inexpensively developed, which can be used by structural engineers for guidance in designing earthquake-resistant structures. This method can be easily deployed in other developing nations to provide these populations with nearly the same level of knowledge and protection against earthquakes that is realized in developed nations.

Deterministic Seismic Hazard Analysis for the State of Haryana, India

The Indian state of Haryana is in a phase of rapid industrial development. In order to help engineers and town planners in designing earthquake resistant structures, it is necessary to carry out site specific seismic hazard analysis and plan mitigation measures. It is apprehended that Indian Code generalises the design peak ground acceleration values which may underestimate the seismic loading in high seismicity regions. Therefore, it is necessary to develop regional seismic hazard scenario in line with the local seismotectonic setting which is consistent with other seismic codes worldwide. In all, 12 seismogenic sources have been identified in the seismic study area. The maximum magnitude has been assigned to each seismogenic source considering regional rupture character. Ground motion prediction equation developed for Indo-Gangetic region by National Disaster Management Authority of India has been used. The peak ground acceleration along with response spectrum for A-type sites for the state have been estimated using state of the art in deterministic seismic hazard analysis methodology. These determined strong motion parameters have been compared with the values given in Indian Standard for criteria for earthquake resistant design of structures to validate them for further practical use. The prepared spectra can be further used to quantify seismic loading for designing earthquake resistant structures in Haryana.

Seismic Performance of Natural Fibre Reinforced Polymer-Concrete Bridge Piers

This paper addresses the usage of new construction materials made of natural fibre reinforced polymer and concrete composite for future earthquake-resistant structures. The structure considered is a simple circular bridge pier. To evaluate the seismic performance of the structure shake table experiments were performed. To reveal the consequence of the magnitude of the ground excitation for the structure the effect of a gradual increase of the peak ground displacement is investigated. The results show that although external damage to the structure cannot be observed the bond between polymer and concrete is a significant factor that determines the performance of the structure.

Cyclic behavior of prefabricated reinforced concrete frame with infill slit shear walls

A composite structural system consisting of prefabricated reinforced concrete frame with infill slit shear walls (PRCFW), with good ductility, is a new type of earthquake resistant structure. Pseudo-static tests were performed to evaluate the seismic behavior of the PRCFW system. Two one-bay, two-story PRCFW specimens were both built at onehalf scale. Additional computational research is also conducted to enhance the nonlinear analytical capabilities for this system. Combined with the concrete damaged plastic (CDP) model provided by finite element program ABAQUS and the constitutive model of concrete proposed by Chinese code, the damage process of the PRCFW structure under cyclic load is simulated. The simulated results show a good agreement with the test data, the dynamic behavior of the PRCFW system can be simulated sufficiently accurate and efficient to provide useful design information. The experimental and numerical study show that this system has the potential to offer good ductility and energy absorption capacity to dissipate input energy, and stiffness adequate for controlling drift for buildings located in earthquake-prone regions.