The response of tall buildings to far-field earthquakes and the case of a 49-storey steel building

The near-fault earthquakes ground motion usually observed a few kilometers away from the active faults generally contains high energetic velocity pulses as a consequence of directivity effects. Mandalay city is located 8 km away from the Sagaing fault, and the comparative study is conducted to evaluate the structural response of 3 different types of Reinforced Concrete buildings - 4-story, 10-story, and 16-story buildings, respectively. These buildings are subjected to bi-directional ground motions selected from both far-field and pulse-like near-fault earthquakes. The far-field earthquakes produce less seismic demand on the buildings when compared to the near-fault earthquakes, where the ratio of the fundamental period of the building to the pulse period is significant. Comparing 2 ground motion selection and scaling methods of Tall Building Initiative guidelines - TBI (2010) and TBI (2017), the latter approach provides a more meaningful definition of intensity measure and allows reducing some conservatism. The structural response obtained from the design Equivalent Lateral Force (ELF) and Response Spectrum Analysis (RSA) is compared with the code-based linear Response History Analysis (RHA) results.

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IMPACT OF PREDICTING BRITTLE FAILURE MODES ON SELECTION OF LIMIT STATES OF VERTICALLY-IRREGULAR TALL BUILDINGS

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2017.166 ◽

2017 ◽

Vol 4 (1) ◽

Author(s):

Aman Mwafy ◽

Sayed Khalifa ◽

Bilal El-Ariss

Keyword(s):

Failure Modes ◽

Limit State ◽

Tall Buildings ◽

International Standards ◽

Performance Criteria ◽

Far Field ◽

Limit States ◽

Earthquake Records ◽

Irregular Buildings ◽

Definition Of

The proper definition of structural failure of irregular structures is a critical element in building vulnerability assessment. Shear force demands may be the main cause of failure under earthquake loading. This increases the uncertainty related to the definition of the limit states of irregular buildings. The present study thus focuses on the assessment of brittle shear failure on the performance criteria of vertically irregular tall buildings. Five 50-story structures are designed using international standards to represent code-conforming tall buildings with main vertical irregularities. Detailed simulation models are used to assess the failure modes of the buildings under the effect of far-field and near-source earthquake records. Experimentally verified shear strength models are adopted to monitor the shear supply-demand response of the reference structures. Based on the comprehensive results obtained from incremental dynamic analyses, it is concluded that shear modeling is essential for the reliable assessment of vertically irregular buildings. The characteristics of earthquake records and the irregularity type significantly influence the limit states of the reference buildings. Unlike the behavior of the buildings under the far-field earthquake scenario, which is controlled by flexure, the collapse prevention limit state is significantly influenced by the member shear response under the effect of near-field earthquakes. Accordingly, improved limit state criteria are proposed, which supports the reliable earthquake loss estimation of tall buildings with different vertical irregularities.

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The Best Location of Belt Truss System in Tall Buildings Using Multiple Criteria Subjected to Blast Loading

Civil Engineering Journal ◽

10.28991/cej-0309177 ◽

2018 ◽

Vol 4 (6) ◽

pp. 1338 ◽

Cited By ~ 10

Author(s):

Reihaneh Tavakoli ◽

Reza Kamgar ◽

Reza Rahgozar

Keyword(s):

Dynamic Analysis ◽

Significant Role ◽

Nonlinear Dynamic ◽

Nonlinear Dynamic Analysis ◽

Tall Buildings ◽

Steel Frame ◽

Equivalent Weight ◽

Steel Building ◽

Different Types ◽

Post Buckling

The main goal of this paper is to investigate the effect of blast phenomenon on structures to determine the best location of belt truss system in tall buildings. For this purpose, one of the exterior frames of a tall steel building, in which the belt truss is located, is considered. The steel frame model is subjected to two different charges of equivalent weight which are applied in two different standoff distances. In this research, the best location of the belt truss system is determined using OpenSees software based on the nonlinear dynamic analysis. The best location of the belt truss system for different types of loading is investigated both with and without considering the post-buckling effect for all members of the belt truss system. The results show that when blast charges are located in a 5-meter range from the building (R=5), post buckling effect of truss elements are more obvious than the case in which blast charges are located in a 10-meter range (R=10); this, in turn, causes the amount of base moment to be completely different when the belt truss is located in the first storey in comparison to the cases where the belt truss is located in any other stories. In addition, if the explosion occurs near the building when the base moment is considered as a criterion, the post buckling effect has a significant role.

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Seismic Fragility of Tall Concrete Wall Structures in Malaysia under Far-Field Earthquakes

The Open Civil Engineering Journal ◽

10.2174/1874149501913010140 ◽

2019 ◽

Vol 13 (1) ◽

pp. 140-146

Author(s):

Siti Aisyah ◽

Mohammadreza Vafaei ◽

Sophia C. Alih ◽

Kotaiba Aljwim

Keyword(s):

Seismic Vulnerability ◽

Fragility Curves ◽

Tall Buildings ◽

Seismic Fragility ◽

Far Field ◽

Concrete Wall ◽

Concrete Walls ◽

Existing Structures ◽

Wall Structures ◽

Story Drift

Introduction: In recent years, the seismic vulnerability of structures in Malaysia has attracted the attention of researchers mainly because the majority of existing structures have not been designed for seismic actions. In this study, seismic vulnerability of tall concrete wall buildings has been investigated through the development of seismic fragility curves. Methods: Two 25-story tall buildings with similar plans but with the different number of parking levels were analyzed through the incremental dynamic analysis. The tall buildings were excited by 15 far-field earthquakes, and their inter-story drift demands and capacities were estimated. Nonlinear response of beams and columns was simulated through the lumped plasticity model. The inelastic response of concrete walls was taken into account through the use of distributed plasticity fibre-based elements. Results and Conclusion: The obtained results indicated that the probability of exceeding minor damage to the tall concrete wall buildings located in the Kuala Lumpur city was around 55%. However, the probability of collapse of these structures in the same city was less than 15%.

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Possible applications of fraunhofer holography in high resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108258 ◽

1978 ◽

Vol 36 (1) ◽

pp. 222-223 ◽

Cited By ~ 1

Author(s):

N. Bonnet ◽

M. Troyon ◽

P. Gallion

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Transfer Function ◽

Radiation Damage ◽

High Resolution Electron Microscopy ◽

Far Field ◽

Field Region ◽

Crystalline Materials ◽

Resolution Electron ◽

The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

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