Mechanisms to limit higher mode effects in a controlled rocking steel frame. 2: Large-amplitude shake table testing

2012 ◽  
Vol 42 (7) ◽  
pp. 1069-1086 ◽  
Author(s):  
Lydell Wiebe ◽  
Constantin Christopoulos ◽  
Robert Tremblay ◽  
Martin Leclerc
Keyword(s):  
Large Amplitude ◽  
Steel Frame ◽  
Shake Table ◽  
Shake Table Testing ◽  
Higher Mode Effects ◽  
Mode Effects

scholarly journals Energy Dissipation in Frame Structures using Sliding Lever Mechanism Technique

2021 ◽  
Vol 15 (1) ◽  
pp. 1-16
Author(s):  
Muhammad Rizwan ◽  
Muhammad Fahad ◽  
Muhammad Naeem ◽  
Mohammad Adil
Keyword(s):  
Energy Dissipation ◽  
Dynamic Testing ◽  
Experimental Studies ◽  
Seismic Energy ◽  
Steel Frame ◽  
Experimental Program ◽  
Frame Structures ◽  
Shake Table ◽  
Shake Table Testing ◽  
Lever Mechanism

Aim: The aim of this study was to investigate the seismic energy dissipation mechanism of a novel and newly proposed sliding lever damping energy dissipation through dynamic shake table testing. Background: Typical energy dissipation systems consist of brace members and installed dampers, which are directly connected to structural members such as beams, columns and joint regions. This can cause additional load concentrations and may require retrofitting or strengthening of existing structures. In order to avoid the load demand on the main structural system, a new energy dissipation technique based on a sliding lever mechanism is proposed and tested through dynamic testing. Objective: The objective of this study was to test a new sliding lever damping energy dissipation through dynamic shake table testing within the scope of steel frame structures. Methods: In order to investigate the proposed energy dissipation configuration, a 1/3rd reduced scaled, three-story and one bay steel frame model has been fabricated and tested in a uni-directional shaking with increasing excitation and, without and with the new technique. For the sliding lever energy dissipation configuration, a non-structural frame (i.e., carrying no gravity loads) has been constructed and provided with an installed ramp-damper assembly. The shaking responses in the form of acceleration and displacement histories have been obtained during the experimental program and compared in order to check the efficiency of the proposed configuration. Results: The results showed a reduction of 55% to 6% in stories deflections and 36% to 12% in acceleration with the newly proposed sliding lever mechanism energy dissipation technique. The top story peak displacements for the damped frame case decreased by 36.55% in case of 0.1 g, 37.95% in case of 0.2g, 31.89% in case of 0.3g, 38.05% in case of 0.4g, 29.37% in case of 0.5g and 12.06% in case of 0.6g shaking excitation. Conclusion: It has been confirmed from the current experimental studies that the new configuration was quite effective in reducing the overall displacement and acceleration response. The reduction in the structural response parameters was very significant during low excitation shaking, whereas, with the increase in shaking intensities, the responses varied with much less difference.

Shake Table Test of a Half-Scale 2-Storey Steel Building Seismically Retrofitted Using Rocking Braced Frame System

2018 ◽  
Vol 763 ◽  
pp. 466-474 ◽  
Author(s):  
Paul Mottier ◽  
Robert Tremblay ◽  
C.A. Rogers
Keyword(s):  
Test Specimen ◽  
Steel Structure ◽  
Shake Table Test ◽  
Shake Table ◽  
Test Program ◽  
Scaled Model ◽  
Braced Frame ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Frame System

The article introduces a shake table test program that was conducted to investigate the response of a two-storey rocking braced frame for which self-centring capacity is provided solely by the gravity loads supported by the frame. The test specimen is a 0.5 scaled model of a prototype rocking frame that was studied for the retrofit of a seismically deficient steel structure. The main objectives of the test program were to study the effects of column uplift and impact on shear forces and moments in the beams connected to the columns. Higher mode effects on brace forces were also of interest. Three different energy dissipation mechanisms located at the rocking interface were examined for drift control: friction, ring spring dampers, and vertical steel bars yielding in tension and buckling in compression. By changing the seismic weight of the test specimen, tests could be conducted for structures located in two different seismic regions of Canada to study the effect of the signature of the ground motions. Increases in beam forces due to column uplift and impact, as predicted by previous numerical simulations, were confirmed by the tests. High axial loads induced by the second vibration mode were also measured in the second storey braces.

Shake table testing of a low damage steel building with asymmetric friction connections (AFC)

2019 ◽  
Vol 155 ◽  
pp. 129-143 ◽  
Author(s):  
Ali A. Rad ◽  
Gregory A. MacRae ◽  
Nikoo K. Hazaveh ◽  
Quincy Ma
Keyword(s):  
Shake Table ◽  
Shake Table Testing ◽  
Steel Building

scholarly journals Shake Table Testing of Self‐Centring Concentrically Braced Frames

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 1949-1956
Author(s):  
Jamie Goggins ◽  
Yadong Jiang ◽  
Brian M. Broderick ◽  
Suhaib Salawdeh ◽  
Gerard J. O'Reilly ◽  
...  
Keyword(s):  
Shake Table ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Shake Table Testing ◽  
Concentrically Braced

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.

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