Dual-plastic hinge design concept for reducing higher-mode effects on high-rise cantilever wall buildings

2009 ◽  
Vol 38 (12) ◽  
pp. 1359-1380 ◽  
Author(s):  
Marios Panagiotou ◽  
José I. Restrepo
Keyword(s):  
Plastic Hinge ◽  
Design Concept ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
High Rise

Inelastic seismic response of concrete shear walls consideringP–delta effects

2001 ◽  
Vol 28 (4) ◽  
pp. 640-655 ◽  
Author(s):  
R Tremblay ◽  
P Léger ◽  
J Tu
Keyword(s):  
Plastic Hinge ◽  
Design Procedure ◽  
Building Code ◽  
Stability Factor ◽  
Dynamic Shear ◽  
Shear Forces ◽  
Inelastic Response ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Wall Structures

The inelastic response of a typical 12-storey ductile reinforced concrete flexural wall is examined under strong earthquake ground motions to determine the importance of P–delta effects and assess the seismic demand in shear and flexure. According to the stability factor approach of the National Building Code of Canada (NBCC) to account for P–delta effects, the flexural strength of the wall has to be increased by as much as 29%. However, the inelastic dynamic analyses indicate that P–delta effects on lateral deformations and curvature ductility demand are negligible for walls that meet the 2% NBCC interstorey drift requirement. The current NBCC stability factor approach to consider P–delta effects is thus overly conservative for shear wall structures, which respond significantly in their second and higher modes of vibration. The analyses also indicate that the magnitude and distribution of shear forces and bending moments in the wall are different from those obtained using the NBCC static design procedure. Plastic hinges can occur above the base of the wall, although the probable moment resistance diagram exceeds the assumed moment envelope after plastic hinge formation at the base. Dynamic amplification of shear forces due to higher mode effects was also observed, which must be accounted for in design. Dynamic shear amplification factors proposed for wall structures in the commentary to the current standard for design of concrete structures in Canada compared well with the results of this study.Key words: seismic, flexural wall, P–delta effects, stability coefficient, inelastic response, National Building Code of Canada, dynamic shear force amplification, higher mode effects.

scholarly journals Numerical Modelling of Reinforced Concrete Slender Walls Subjected to Coupled Axial Tension–Flexure

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Xiaowei Cheng ◽  
Haoyou Zhang
Keyword(s):  
Reinforced Concrete ◽  
Plastic Hinge ◽  
Element Model ◽  
Lateral Loading ◽  
Design Parameters ◽  
Seismic Behaviour ◽  
High Rise ◽  
Ultimate Deformation ◽  
Axial Tension ◽  
Plastic Hinge Length

AbstractUnder strong earthquakes, reinforced concrete (RC) walls in high-rise buildings, particularly in wall piers that form part of a coupled or core wall system, may experience coupled axial tension–flexure loading. In this study, a detailed finite element model was developed in VecTor2 to provide an effective tool for the further investigation of the seismic behaviour of RC walls subjected to axial tension and cyclic lateral loading. The model was verified using experimental data from recent RC wall tests under axial tension and cyclic lateral loading, and results showed that the model can accurately capture the overall response of RC walls. Additional analyses were conducted using the developed model to investigate the effect of key design parameters on the peak strength, ultimate deformation capacity and plastic hinge length of RC walls under axial tension and cyclic lateral loading. On the basis of the analysis results, useful information were provided when designing or assessing the seismic behaviour of RC slender walls under coupled axial tension–flexure loading.

Determination of seismic design forces by equivalent static load method

2003 ◽  
Vol 30 (2) ◽  
pp. 287-307 ◽  
Author(s):  
JagMohan Humar ◽  
Mohamed A Mahgoub
Keyword(s):  
Seismic Design ◽  
Static Load ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Uniform Hazard Spectrum ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Equivalent Static Load ◽  
Adjustment Factors ◽  
Mode Vibration

In the proposed 2005 edition of the National Building Code of Canada (NBCC), the seismic hazard will be represented by uniform hazard spectra corresponding to a 2% probability of being exceeded in 50 years. The seismic design base shear for use in an equivalent static load method of design will be obtained from the uniform hazard spectrum for the site corresponding to the first mode period of the building. Because this procedure ignores the effect of higher modes, the base shear so derived must be suitably adjusted. A procedure for deriving the base shear adjustment factors for different types of structural systems is described and the adjustment factor values proposed for the 2005 NBCC are presented. The adjusted base shear will be distributed across the height of the building in accordance with the provisions in the current version of the code. Since the code-specified distribution is primarily based on the first mode vibration shape, it leads to an overestimation of the overturning moments, which should therefore be suitably adjusted. Adjustment factors that must be applied to the overturning moments at the base and across the height are derived for different structural shapes, and the empirical values for use in the 2005 NBCC are presented.Key words: uniform hazard spectrum, seismic design base shear, equivalent static load procedure, higher mode effects, base shear adjustment factors, distribution of base shear, overturning moment adjustment factors.

scholarly journals An Optimal Seismic Force Pattern for Uniform Drift Distribution

Buildings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 231 ◽  
Author(s):  
Rosario Montuori ◽  
Elide Nastri ◽  
Bonaventura Tagliafierro
Keyword(s):  
Low Cycle Fatigue ◽  
Force Distribution ◽  
Premature Failure ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Seismic Force ◽  
Uniform Drift ◽  
Load Pattern ◽  
Set Up ◽  
Cyclic Damage

The force distribution proposed by codes, which in many cases is framed in the equivalent static force procedure, likely leads to design structures with non-uniform drift distribution in terms of inter-storey drift and ductility demands. This can lead to an unbalanced drift demand at certain storeys. This phenomenon may also amass cyclic damage to the dissipative elements at this very storey, therefore increasing the probability of premature failure for low-cycle fatigue. This work proposes a new force design distribution that accounts for higher mode effects and limits the displacement concentration at any storey thus improving the dissipative capacity of the whole structures. The main advantage of the proposed method stands in its formulation, which allows to spare any previous set up with structural analyses. The proposed force distribution has been applied to multi-degree-of-freedom systems to check its effectiveness, and the results have been compared with other proposals. In addition, in order to obtain a further validation of the proposed force distribution, the results obtained by using a genetic algorithm have been evaluated and compared. Additionally, the results provided in this work validate the proposed procedure to develop a more efficient lateral load pattern.

Research and Development of Household Fire Refuge Cabin

2013 ◽  
Vol 433-435 ◽  
pp. 2267-2276 ◽  
Author(s):  
Huai Chao Yan ◽  
Lin Jie Li ◽  
Jun Ge Huang
Keyword(s):  
Research And Development ◽  
Present Situation ◽  
Design Concept ◽  
Development Status ◽  
Building Fire ◽  
High Rise ◽  
High Rise Building ◽  
Fire Evacuation ◽  
International Mine ◽  
Fire Accidents

With the high-rise building fire accidents have increased every year, the appearance of home fire evacuation cabin has a very important significance.At first,We introduced the development status of domestic and international mine refuge Chamber and two mine refuge Chamber products which was used commonly,and analysed their merit and shortcoming,where we could get the inspiration;Then we focused on the present situation of the household refuge compartment and analysis of its shortcomings and the main problems need to be solved;Finally we put forward the design concept of the household fire refuge cabin .

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