scholarly journals Examination of Structures Built with Tunnel Formwork in Terms of Strength and Cost according to the Earthquake Regulations of 2007 and 2018

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Yilmaz Dilek ◽  
Abdulhalim Karasin
Keyword(s):  
Empirical Formula ◽  
Active Fault ◽  
Design Analysis ◽  
Total Cost ◽  
Earthquake Loads ◽  
Ground Movements ◽  
Regular Structures ◽  
Irregular Structures ◽  
Floor Plans ◽  
Fault Lines

Turkey has always been exposed to active fault lines passing through and unpredictable seismic activities. These ground movements have always been one of the important issues in our country, which have led to great destruction and loss of lives and property in its past. For this reason, our earthquake regulations, which aim to design more accurately against earthquake movements, are continuously made improvements. In this study, the analysis of structures built with tunnel formwork system which is popular today with the new earthquake regulations entered into force in 2018, and the strength and cost according to the old earthquake regulation in terms of what differences will occur. In addition to the study, we investigated how the number of floors and regular floor plans affects the results. For this purpose, two types of structures were covered with 5, 10, and 15 storey models created, first in the 2007 earthquake regulation; then, in the 2018 earthquake regulation, design analysis was carried out. As a result, the new earthquake regulation, which came into force in 2018, led to more realistic results as it provides more accurate environmental inputs used in design analysis. Earthquake loads affecting floors increased by 3.9% for 5 storey in regular structures, decreasing by 38.4% for 10 stories and 43.3% for 15 stories. More irregular structures increased 7.3% for 5 storey, 10-storey structures decreased by 38.9%, and 15-storey structures decreased by 43.6%. In terms of cost, there was a 0.07% increase in total cost in 5-storey buildings, 2.45% in 10-storey buildings, and a 3.91% reduction in 15-storey buildings. In addition to these results, an empirical formula that estimates m2 prices depending on the number of floors was obtained.

scholarly journals A Study on the Effects of Vertical Mass Irregularity on Seismic Behavior of BRBFs and CBFs

2020 ◽  
Vol 10 (23) ◽  
pp. 8314
Author(s):  
Armin Karami ◽  
Shahrokh Shahbazi ◽  
Mahdi Kioumarsi
Keyword(s):  
Urban Areas ◽  
Seismic Behavior ◽  
Steel Structures ◽  
Mean Value ◽  
Far Field ◽  
Braced Frames ◽  
Regular Structures ◽  
Irregular Structures ◽  
The Mean ◽  
Economic Constraints

Today, architectural application and economic constraints require that vertical-irregular structures be constructed in urban areas. Proposing methods to minimize damage to these structures during earthquakes is therefore crucial. Strict regulations have been enforced for the design and analysis of irregular structures given their higher vulnerability to damage compared to that of regular structures. The present study aimed to evaluate eight regular and irregular 10-story and 15-story steel structures with buckling-restrained braces frames (BRBFs) and concentric braced frames (CBFs) in terms of their responses to twelve far-field earthquakes. According to the obtained results, the mean value of maximum drift, top floor displacement and floor acceleration were higher in both regular and irregular structures with BRBFs than in those with CBFs.

Determination of structural irregularity limits

2009 ◽  
Vol 42 (4) ◽  
pp. 288-301 ◽  
Author(s):  
Vinod K. Sadashiva ◽  
Gregory A. MacRae ◽  
Bruce L. Deam
Keyword(s):  
Time History ◽  
Static Method ◽  
Simple Analysis ◽  
Floor Level ◽  
Analysis Techniques ◽  
Regular Structures ◽  
Irregular Structures ◽  
History Analysis ◽  
Interstorey Drift ◽  
Dynamic Time

Structures may be irregular due to non-uniform distributions of mass, stiffness, strength or due to their structural form. For regular structures, simple analysis techniques such as the Equivalent Static Method, have been calibrated against advanced analysis methods, such as the Inelastic Dynamic Time-History Analysis. Most worldwide codes allow simple analysis techniques to be used only for structures which satisfy regularity limits. Currently, such limits are based on engineering judgement and lack proper calibration. This paper describes a simple and efficient method for quantifying irregularity limits. The method is illustrated on 3, 5, 9 and 15 storey models of shear-type structures, assumed to be located in Wellington, Christchurch and Auckland. They were designed in accordance with the Equivalent Static Method of NZS 1170.5. Regular structures were defined to have constant mass at every floor level and were either designed to produce constant interstorey drift ratio at all the floors simultaneously or to have a uniform stiffness distribution over their height. Design structural ductility factors of 1, 2, 4 and 6, and target (design) interstorey drift ratios ranging between 0.5% and 3% were used in this study. Inelastic dynamic time-history analysis was carried out by subjecting these structures to a suite of code design level earthquake records. Irregular structures were created with floor masses of magnitude 1.5, 2.5, 3.5 and 5 times the regular floor mass. These increased masses were considered separately at the first floor level, mid-height and at the roof. The irregular structures were designed for the same drifts as the regular structures. The effect of increased mass at the top or bottom of the structure tended to increase the median peak drift demands compared to regular structures for the record suite considered. When the increased mass was present at the mid-height, the structures generally tended to produce lesser drift demands than the corresponding regular structures. A simple equation was developed to estimate the increase in interstorey drift due to mass irregularity. This can be used to set irregularity limits.

Dominance of irregular structures in the formation of intramolecular antiparallel β sheets by homopolyamino acids

1985 ◽  
Vol 63 (1) ◽  
pp. 140-146 ◽  
Author(s):  
Wayne L. Mattice ◽  
Eok Lee ◽  
Harold A. Scheraga
Keyword(s):  
Partition Function ◽  
Growth Parameter ◽  
Globular Proteins ◽  
Matrix Formulation ◽  
End Effects ◽  
Regular Structures ◽  
Irregular Structures ◽  
Unequal Number ◽  
Β Sheets ◽  
Two Parameters

A matrix formulation of the conformational partition function is used to assess the influence of irregular structures on the formation of intramolecular antiparallel β sheets. An antiparallel sheet is considered to be irregular if any pair of contiguous strands has an unequal number of residues. The regular structures in the model consist of antiparallel sheets in which every strand contains the same number of residues. Aside from a growth parameter t, the model contains two parameters that account for the influence of edge effects. Each tight turn contributes a factor δ, and each residue in the sheet that does not have a partner in a preceding strand contributes a factor τ. When τ < δ = 1, preferred sheets consist of an extremely large number of very short strands. Such sheets resemble those found in cross-β fibers. Irregular structures increase the cooperativity of the formation of cross-β fibers. They cause the fibers that are formed to be longer (have more strands) and thicker (have more residues per strand) than if all antiparallel sheets were regular. A much different result is obtained if end effects are modified so that the antiparallel sheets formed resemble those found in globular proteins. Formation of antiparallel sheets remains cooperative, but irregular sheets now markedly reduce the cooperativity of the transition. At high antiparallel-sheet content, irregular structures cause typical antiparallel sheets to be smaller. The behavior of the conformational partition function shows that irregular structures make the dominant contribution to both transitions. Therefore, formulations that restrict consideration to regular structures may provide a misleading picture of antiparallel-sheet formation.

scholarly journals Repair Strategies for failed feature specification in Japanese: Evidence from loanwords, a reversing word game, and blending

2017 ◽  
Vol 4 ◽  
Author(s):  
Daiho Kitaoka
Keyword(s):  
Repair Processes ◽  
Regular Structures ◽  
Irregular Structures ◽  
Usual Manner ◽  
Word Game ◽  
Core Lexicon

This paper demonstrates repair strategies when place feature of the special moras in Japanese (the second half of a long vowel, moraic nasals, and the first half of a double consonant) fail to be specified in a usual manner. I posit three repair processes based on the observations of marked environments (loanwords, a word game called Sakasa Kotoba, blending): (i) over-application of regular structures in core lexicon, (ii) irregular structures that are produced through The Emergence of the Unmarked (TETU), and (iii) game-specific structures. I illustrate that even in marked environments, repair processes make outcome structures as unmarked as possible with these strategies. Based on the observations in the marked environments (mainly from Sakasa Kotoba), I further discuss the process of morification and underlying representations of special moras.

A scenario-based methodology for determining fire resistance ratings of irregular steel structures

2019 ◽  
Vol 23 (1) ◽  
pp. 89-103
Author(s):  
Behrouz Behnam
Keyword(s):  
Fire Resistance ◽  
Safety Margin ◽  
Steel Structures ◽  
Soft Story ◽  
Regular Structures ◽  
Natural Fires ◽  
Irregular Structures ◽  
Fire Scenarios ◽  
Fire Resistance Rating ◽  
Resistance Rating

This article investigates the response of irregular steel structures under natural fires. As the severity and duration of natural fires depend on many factors, a probabilistic-based approach known as two-level factorial design is used, whereby possible fire scenarios are considered based on the minimum and maximum values of the involved factors. Two seven-story regular steel structures with three span lengths of 5500 and 7000 mm are designed to meet a 2.0-hr fire resistance rating based on the ISO834 fire. Two types of irregularities, setback and soft story, are then imposed on the regular structures to make them irregular. The regular and irregular structures are then exposed to the fire scenarios (32 in total) to evaluate their fire resistance ratings. The results show that while the regular structures are able to meet the required fire resistance rating under all of the fire scenarios, this is not the case for the irregular structures. It is shown that the reduction in the fire resistance ratings of the setback and the soft-story structures can be as low as 45% and 33% that of the required fire resistance ratings, respectively. Also, the setback irregular structures tend to collapse laterally, hence endangering the safety of adjacent buildings. To address the above deficiencies, it is proposed here that the maximum surface temperature on the structural members should be limited to 415°C–460°C. Alternatively, providing a 20%–25% increase in the insulation thickness can provide the required safety margin as dictated by fire codes.

Effects of coupled vertical stiffness-strength irregularity due to modified interstorey height

2011 ◽  
Vol 44 (1) ◽  
pp. 31-44
Author(s):  
Vinod K. Sadashiva ◽  
Gregory A. MacRae ◽  
Bruce L. Deam
Keyword(s):  
Time History ◽  
Lateral Force ◽  
Code Design ◽  
Maximum Increase ◽  
Vertical Stiffness ◽  
Regular Structures ◽  
Irregular Structures ◽  
Drift Ratio ◽  
Interstorey Drift ◽  
Dynamic Time

Structures may have vertical stiffness or strength irregularity for many reasons. In many practical cases, a change in storey stiffness, results a change in strength at the same storey. In this paper, the effect of a change in interstorey height is quantified. In order to do this, relationships between storey stiffness and strength resulting due to a modified interstorey height for a few common lateral force resisting systems was considered. It was applied to simple shear-type structures of 3, 5, 9 and 15 storeys, assumed to be located in Wellington. All structures were considered to have a constant mass at every floor level. Both regular and irregular structures were designed in accordance with the Equivalent Static method of the current New Zealand seismic design Standard, NZS 1170.5. Regular structures were designed to either (i) produce a constant target interstorey drift ratio at all the storeys simultaneously or (ii) to have uniform stiffness distribution over the height of the structure, with the target interstorey drift ratio at the first storey. An “interstorey height ratio” was defined as the ratio of modified to initial interstorey height, and applied separately at the first storey, mid-height storey and at the topmost storey by amounts between 0.5 and 3. The modified structures were then redesigned until the target interstorey drift ratio was achieved at the critical storey/storeys. Design structural ductility factors of 1, 2, 3, 4 and 6, and target (design) interstorey drift ratios ranging between 0.5% and 3%, were used in this study. Inelastic dynamic time-history analysis was carried out by subjecting these structures to code design level earthquake records, and the maximum interstorey drift ratio demands due to each record were used to compare the responses of regular and irregular structures. It was found that structural types in which only the storey stiffness was modified due to a change in the interstorey height produced the maximum increase in drift demands rather than structural forms with other stiffness-strength coupling cases. Shorter structures having an increased first storey height, and taller structures with an increased middle storey height generally produced greater interstorey drift demands than regular structures. For cases of increased storey stiffness due to decreased storey heights, the shorter structures with a decreased middle storey height resulted in higher median peak ISDR due to irregularity. A simple equation describing the maximum increase in response due to modifications to a storey height was developed. The equation was used along with the realistic correlations between storey stiffness and strength to obtain the governing code regularity limit.

A Study on Mass Irregularity Limits of RC Structures for Various Seismic Zones of India

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Mahammad Fayeemuddin ◽  
A. Vimala
Keyword(s):  
Aspect Ratio ◽  
Response Spectrum ◽  
Lateral Loads ◽  
Base Shear ◽  
Response Spectrum Analysis ◽  
Rc Structures ◽  
Seismic Zones ◽  
Regular Structures ◽  
Irregular Structures ◽  
Standard Code

The performance of any structure under lateral loads depends on its structural configuration. Most of the codes worldwide mentioned the provisions for the lateral load analysis for regular structures. Structures may be irregular in practice due to uneven distributions in mass, stiffness and strength. In India, most common type of multi-storied apartments constructed varies from 5 to 15 storeys and many apartments are constructed with penthouse which creates mass irregularity in the structures. The present study investigates the performance of mass irregular structures which are created by providing penthouse and also modeled as a stepped setback structure. Total four structures, 5, 7, 11 and 16 storied with an aspect ratio (height to width of the structure) of 0.64, 0.88, 1.36 and 1.96 are considered. For each structure response spectrum analysis is carried and the response parameters like storey displacements, storey drift and base shear variation in 4 seismic zones of India is studied. The main focus of the investigation is to understand the acceptance of mass irregularity with respect to the aspect ratio of the structure. The acceptance limit of the mass irregularity is also investigated as per 4 seismic zones of India. The results are compared with Indian standard code limits and concluded the acceptance limit as per seismic zones of India.

scholarly journals Analysis of Irregular Structures under Earthquake Loads

2019 ◽  
Vol 14 ◽  
pp. 806-819
Author(s):  
Siva Naveen E ◽  
Nimmy Mariam Abraham ◽  
Anitha Kumari S D
Keyword(s):  
Earthquake Loads ◽  
Irregular Structures

scholarly journals Seismic Ductility Reduction of Flexural-type Structures with Vertical Irregularities

2016 ◽  
Vol 10 (1) ◽  
pp. 1-11
Author(s):  
Weifeng Zhao ◽  
Xiaoquan Hu ◽  
Zhilin Long
Keyword(s):  
Ground Motions ◽  
Reduction Factor ◽  
Earthquake Excitation ◽  
Regular Structures ◽  
Irregular Structures ◽  
Ductility Reduction Factor ◽  
Reduction Factors

Seismic ductility reduction factors for flexural-type structures with vertical irregularities subjected to pulse-like and non-pulse-like ground motions are investigated in this paper. By establishing various multi-node flexural cantilever-column models, the ductility reduction factor of vertically irregular structures is studied by modifying the ductility reduction factor of irregular structures. The effects of various factors such as ductility level, irregular ratio and pulse-like earthquake excitation on modification coefficient are also explored. The analysis results reveal that: 1) the modification coefficient decreases with smaller irregularity ratio; 2) ductility reduction factors for vertically irregular structures are significantly smaller than those of regular structures; 3) ductility level exerts a certain influence on ductility reduction factor without an obvious trend; and 4) the modification coefficient under pulse-like excitation is smaller than those from non-pulse-like motions and the influence of pulse-like earthquake is coupled with irregularity ratio. This paper concludes with the statistical outcomes based on average of results and recommends modified factors for practice uses.

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