Bergsprungur og byggingar á höfuðborgarsvæðinu

2018 ◽  
Vol 24 ◽  
pp. 25-29
Author(s):  
Páll Einarsson ◽  
Haukur Jóhannesson ◽  
Ásta Rut Hjartardóttir
Keyword(s):  
Metropolitan Area ◽  
Urban Areas ◽  
Structural Damage ◽  
Seismic Waves ◽  
Relative Displacement ◽  
Building Structures ◽  
Engineering Structures ◽  
Volcanic System ◽  
Tectonic Plates ◽  
Building Practice

Straddling the boundary between two of the major tectonic plates on Earth, Iceland offers unique conditions for engineering structures that require special attention. Urban areas are rapidly expanding into areas where the bedrock is cut by numerous active fractures and faults. The fissure swarm of the Krísuvík volcanic system runs through the outskirts of Reykjavík and other towns of the metropolitan area. Activity of its fractures mostly occurs during magmatic events along the Reykjanes Peninsula oblique rift on a thousand years timescale. Hazard caused by the fractures is mostly twofold: Relative displacement of the walls of the fracture during magmatic intrusion and small relative displacements during the passage of seismic waves from distant earthquakes may damage structures built across them. The risk of structural damage may most likely be reduced considerably by avoiding building structures across the fractures. We suggest a change in building practice in fractures areas to achieve that.

TECHNICAL SEISMICITY AND STRUCTURAL NOISE SPREADING FROM TRANSPORT - THEIR INFLUENCE ON BUILDINGS CONSTRUCTIONS

Akustika ◽  
2020 ◽  
Vol 36 (36) ◽  
pp. 35-45
Author(s):  
Jana Dolejší ◽  
Jan Dolejší
Keyword(s):  
Urban Areas ◽  
Rail Transport ◽  
Building Construction ◽  
Building Structures ◽  
Structural Noise ◽  
Railway Tunnel ◽  
Noise And Vibration ◽  
Influence Of Noise

This paper deals with the influence of noise and vibration sources from which vibrations propagate through subsoil into building structures. Structural noise is usually then emitted by building structures into interiors. Especially within city centers and urban areas the approach of building construction towards sources such as road and rail transport differ in particular, whether the objects are located directly above the metro or railway tunnel, or objects close to roads or railways.

A periodic seismic isolation foundation with an extremely broad low-frequency attenuation zone: Theoretical analysis and experimental verification

2021 ◽  
pp. 136943322110646
Author(s):  
Peng Zhou ◽  
Shui Wan ◽  
Xiao Wang ◽  
Yingbo Zhu ◽  
Muyun Huang
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Periodic Structures ◽  
Finite Size ◽  
Low Frequency ◽  
Bridge Structure ◽  
Engineering Structures ◽  
P Waves ◽  
New Type ◽  
Dominant Frequencies

The attenuation zones (AZs) of periodic structures can be used for seismic isolation design. To cover the dominant frequencies of more seismic waves, this paper proposes a new type of periodic isolation foundation (PIF) with an extremely wide low-frequency AZ of 3.31 Hz–17.01 Hz composed of optimized unit A with a wide AZ and optimized unit B with a low-frequency AZ. The two kinds of optimized units are obtained by topology optimization on the smallest periodic unit with the coupled finite element-genetic algorithm (GA) methodology. The transmission spectra of shear waves and P-waves through the proposed PIF of finite size are calculated, and the results show that the AZ of the PIF is approximately the superposition of the AZs of the two kinds of optimized units. Additionally, shake tests on a scale PIF specimen are performed to verify the attenuation performance for elastic waves within the designed AZs. Furthermore, numerical simulations show that the acceleration responses of the bridge structure with the proposed PIF are attenuated significantly compared to those with a concrete foundation under the action of different seismic waves. Therefore, the newly proposed PIF is a promising option for the reduction of seismic effects in engineering structures.

Seismic microzoning in New Zealand

1971 ◽  
Vol 4 (1) ◽  
pp. 43-50
Author(s):  
W. R. Stephenson
Keyword(s):  
New Zealand ◽  
Structural Damage ◽  
Seismic Waves ◽  
Multiple Reflection ◽  
Ground Failure ◽  
Seismic Microzoning ◽  
Popular View ◽  
Wave Trains ◽  
Local Geology ◽  
Ground Damage

"Seismic Microzoning" means many different things to different people. There is always included the element of different damage in nearby areas, but how the differences arise, how we should study them, and how we should apply the results of our studies, are still uncertain. To some people, microzoning refers to structural damage due to ground failure; faulting, slumping and liquefaction all belong in this category. To others, microzoning is the effects of the focussing of seismic waves by boundaries, resulting in modified ground damage and building damage. A third very popular view of microzoning holds that it concerns multiple reflection of seismic waves in layers, with interference of the wave trains giving rise to maxima, where ground and structural damage will be accentuated. Microzoning can be defined as the division of land areas into small regions of differing local geology for which differences in earthquake attack on structures are specified. This paper is an attempt to set down aspects of microzoning in a logical manner, and to relate them. It also discusses activities here and overseas, and considers where microzoning and microzoning research in New Zealand should head.

Periodic Materials-Based 3D Seismic Base Isolators for Nuclear Power Plants

2014 ◽  
Author(s):  
Y. Yan ◽  
A. Laskar ◽  
Z. Cheng ◽  
F. Menq ◽  
Y. Tang ◽  
...  
Keyword(s):  
Earthquake Engineering ◽  
Structural Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Natural Frequencies ◽  
Field Tests ◽  
Band Gaps ◽  
Solid State Physics ◽  
Periodic Materials

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.

Review on Damage Identification and Diagnosis Research of Civil Engineering Structure

2014 ◽  
Vol 1006-1007 ◽  
pp. 34-37 ◽  
Author(s):  
Hong Ni ◽  
Ming Hui Li ◽  
Xi Zuo
Keyword(s):  
Structural Damage ◽  
Civil Engineering ◽  
Damage Identification ◽  
Engineering Structures ◽  
Engineering Structure ◽  
Civil Engineering Structure ◽  
Structure Damage ◽  
Development Direction ◽  
Structural Damage Identification ◽  
Civil Engineering Structures

This paper first describes the importance of structural damage identification and diagnosis in civil engineering, and introduces domestic and foreign status of damage identification and diagnosis methods, and on the basis of this, it also introduces all kinds of methods for damage identification and diagnosis of civil engineering structures, and finally puts forward the development direction of civil engineering structure damage identification and diagnosis.

scholarly journals Crack Identification and Localization In Structural Beams Using Numerical and Experimental Modal Analysis- A Review

2020 ◽  
pp. 62-68
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Structural Damage ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Crack Identification ◽  
Engineering Structures ◽  
Aircraft Wings ◽  
Crack Location ◽  
Damaged Beams

This article presents a critical review of recent research done on crack identification and localization in structural beams using numerical and experimental modal analysis. Crack identification and localization in beams are very crucial in various engineering applications such as ship propeller shafts, aircraft wings, gantry cranes, and Turbo machinery blades. It is necessary to identify the damage in time; otherwise, there may be serious consequences like a catastrophic failure of the engineering structures. Experimental modal analysis is used to study the vibration characteristics of structures like natural frequency, damping and mode shapes. The modal parameters like natural frequency and mode shapes of undamaged and damaged beams are different. Based on this reason, structural damage can be detected, especially in beams. From the review of various research papers, it is identified that a lot of the research done on beams with open transverse crack. Crack location is identified by tracking variation in natural frequencies of a healthy and cracked beam

Direct adaptive algorithm for seismic control of damaged structures with faulty sensors

2017 ◽  
Vol 24 (24) ◽  
pp. 5854-5866 ◽  
Author(s):  
Amin Hosseini ◽  
Touraj Taghikhany ◽  
Arash Yeganeh Fallah
Keyword(s):  
Adaptive Control ◽  
Seismic Response ◽  
Structural Damage ◽  
Control Method ◽  
Control Strategies ◽  
Magnetorheological Damper ◽  
Main Concern ◽  
Building Structures ◽  
Steel Moment Resisting Frames ◽  
Seismic Control

In recent decades, the application of semi-active control strategies has gained much attention as a way to reduce the seismic response of civil infrastructures. However, uncertainty in the modeling process of systems with possible partial or total failure during an earthquake is the main concern of engineers about the reliability of this strategy. In this regard, adaptive control algorithms are known as an effective solution to adjust control parameters with different uncertainties. In the current study, the efficiency of the simple adaptive control method (SACM) is investigated to control the seismic response of building structures in the presence of unknown structural damage and fault in the sensors. The method is evaluated in 20-story steel moment resisting frames with different arrangement of smart dampers and sensors with various damage and fault scenarios. The results show that the SACM control system can effectively reduce the maximum inter-story drift of the structure in all different assumed magnetorheological damper arrangements. Furthermore, combination of a Kalman–Bucy filter with the SACM improves robustness of the controller to the uncertainties of sensors faults and damages of structural elements.

A Vibration-Based Structural Damage Detection Method and its Applications to Engineering Structures

2011 ◽  
Author(s):  
K. He ◽  
W. D. Zhu
Keyword(s):  
Damage Detection ◽  
Iterative Algorithm ◽  
Structural Damage ◽  
Detection Method ◽  
New Physics ◽  
Logistic Function ◽  
Frame Structure ◽  
Engineering Structures ◽  
System Equations ◽  
Extent Of Damage

Two major challenges associated with a vibration-based damage detection method using changes in natural frequencies are addressed: accurate modeling of structures and the development of a robust inverse algorithm to detect damage, which are defined as the forward and inverse problems, respectively. To resolve the forward problem, new physics-based finite element modeling techniques are developed for fillets in thin-walled beams and for bolted joints, so that complex structures can be accurately modeled with a reasonable model size. To resolve the inverse problem, a logistic function transformation is introduced to convert the constrained optimization problem to an unconstrained one, and a robust iterative algorithm using the Levenberg-Marquardt method is developed to accurately detect the locations and extent of damage. The new methodology can ensure global convergence of the iterative algorithm in solving under-determined system equations and deal with damage detection problems with relatively large modeling error and measurement noise. It is applied to various engineering structures including lightning masts, a space frame structure and one of its components, and a pipeline. The exact locations and extent of damage can be detected in the numerical simulation, and the locations and extent of damage can be successfully detected in experimental damage detection.

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