scholarly journals Performance-based optimal distribution of viscous dampers in ‎structure using hysteretic energy compatible endurance time excitations

2021 ◽  
Vol 5 (3) ◽  
pp. 46-55
Author(s):  
A. Shirkhani ◽  
B. Farahmand Azar ◽  
M. Charkhtab Basim ◽  
M. Mashayekhi ◽  
◽  
...  
Keyword(s):  
Optimal Distribution ◽  
Viscous Dampers ◽  
Endurance Time ◽  
Hysteretic Energy

Optimal Distribution of Damping Coefficients for Viscous Dampers in Buildings

2017 ◽  
Vol 17 (04) ◽  
pp. 1750054 ◽  
Author(s):  
Tzu Kang Lin ◽  
Jenn Shin Hwang ◽  
Kuan Hui Chen
Keyword(s):  
Damping Ratio ◽  
Optimization Method ◽  
Design Guidelines ◽  
Damping Coefficient ◽  
Optimal Distribution ◽  
Viscous Dampers ◽  
Moment Frame ◽  
Practical Applications ◽  
Soft Story ◽  
Damping Coefficients

Design guidelines for implementing viscous dampers to buildings have been broadly included in seismic design codes worldwide. Although the relationship between the damping coefficient of viscous dampers and the added damping ratio to the structure has been theoretically studied, the process of distributing the damping coefficient onto each story of a building has not been regulated by the codes. For practical applications, some distribution methods have been previously proposed. However, no comparison has been made between these proposed methods considering the controllability and design economy. In this paper, two search methods based on the genetic algorithms (GAs) are adopted to examine the optimal distribution of damping coefficients. The results are then compared with a variety of existing distribution methods. A comparison is made for the distribution methods assuming the same added damping ratio for the structure. Three two-dimensional frames are adopted in the comparison: a regular moment frame, a moment frame with a soft-story, and a setback building. The results indicated that similar seismic response reduction can be achieved by using different distribution methods if the supplemental damping ratio is the same, while the optimal story damping coefficient can be obtained by using the proposed optimization method. Moreover, the “story shear strain energy to efficient stories” (SSSEES) method, among others, offers advantages in terms of seismic reduction efficiency, economical design, and practical application simplicity.

scholarly journals Assessing Seismic Performance of Gantry Crane Subjected to Near-Field Ground Motions Using Incremental Dynamic and Endurance Time Analysis Methods

2022 ◽  
Vol 2022 ◽  
pp. 1-14
Author(s):  
Qihui Peng ◽  
Wen-ming Cheng ◽  
Peng Guo ◽  
Hongyu Jia
Keyword(s):  
Seismic Performance ◽  
Incident Angle ◽  
Ground Motions ◽  
Near Field ◽  
Maxwell Model ◽  
Element Model ◽  
Gantry Crane ◽  
Time Analysis ◽  
Viscous Dampers ◽  
Endurance Time

Assessing the seismic performance of the gantry crane is significant since the structure is more vulnerable to earthquakes with the increase in size and lifting weight capacity. This paper aims to investigate the seismic response of the gantry crane incorporating near-field ground motions using incremental dynamic and endurance time analysis (IDA and ETA) methods. To model the structure accurately, a nonlinear finite element model of the gantry crane considering the viscoelastic effect is developed in the OpenSees platform. Then, the IDA method is also carried out for a comparison with the ETA method. The results of the two methods are consistent with a correlation of 93.9% while the computational demand of the ETA method is much less than those of the IDA method. To study further, both the seismic incident angle and the application of viscous dampers using the Maxwell model are analyzed and discussed in detail. The results show that seismic incident angle has a distinct influence on the maximum seismic displacement and viscous dampers can significantly reduce the seismic demand of the gantry crane. These findings support the seismic design of gantry cranes and evaluate the structural seismic performance efficiently.

Development of hysteretic energy compatible endurance time excitations and its application

2018 ◽  
Vol 177 ◽  
pp. 753-769 ◽  
Author(s):  
Mohammadreza Mashayekhi ◽  
Homayoon E. Estekanchi ◽  
Hassan Vafai ◽  
S. Ali Mirfarhadi
Keyword(s):  
Endurance Time ◽  
Hysteretic Energy

Skin Cooling on Breath-Hold Duration and Predicted Emergency Air Supply Duration During Immersion

2020 ◽  
Vol 91 (7) ◽  
pp. 578-585
Author(s):  
Victory C. Madu ◽  
Heather Carnahan ◽  
Robert Brown ◽  
Kerri-Ann Ennis ◽  
Kaitlyn S. Tymko ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Hold Time ◽  
Whole Body ◽  
Breath Hold ◽  
Endurance Time ◽  
Skin Exposure ◽  
Breathing Apparatus ◽  
Air Supply ◽  
Skin Cooling ◽  
Breath Hold Duration

PURPOSE: This study was intended to determine the effect of skin cooling on breath-hold duration and predicted emergency air supply duration during immersion.METHODS: While wearing a helicopter transport suit with a dive mask, 12 subjects (29 ± 10 yr, 78 ± 14 kg, 177 ± 7 cm, 2 women) were studied in 8 and 20°C water. Subjects performed a maximum breath-hold, then breathed for 90 s (through a mouthpiece connected to room air) in five skin-exposure conditions. The first trial was out of water for Control (suit zipped, hood on, mask off). Four submersion conditions included exposure of the: Partial Face (hood and mask on); Face (hood on, mask off); Head (hood and mask off); and Whole Body (suit unzipped, hood and mask off).RESULTS: Decreasing temperature and increasing skin exposure reduced breath-hold time (to as low as 10 ± 4 s), generally increased minute ventilation (up to 40 ± 15 L · min−1), and decreased predicted endurance time (PET) of a 55-L helicopter underwater emergency breathing apparatus. In 8°C water, PET decreased from 2 min 39 s (Partial Face) to 1 min 11 s (Whole Body).CONCLUSION: The most significant factor increasing breath-hold and predicted survival time was zipping up the suit. Face masks and suit hoods increased thermal comfort. Therefore, wearing the suits zipped with hoods on and, if possible, donning the dive mask prior to crashing, may increase survivability. The results have important applications for the education and preparation of helicopter occupants. Thermal protective suits and dive masks should be provided.Madu VC, Carnahan H, Brown R, Ennis K-A, Tymko KS, Hurrie DMG, McDonald GK, Cornish SM, Giesbrecht GG. Skin cooling on breath-hold duration and predicted emergency air supply duration during immersion. Aerosp Med Hum Perform. 2020; 91(7):578–585.

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