scholarly journals Evaluating the Vertical Extension Module of a Building with Installed Rotary Dampers at Joints

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 536
Author(s):  
Seokjae Heo ◽  
Seunguk Na ◽  
Moo-Won Hur ◽  
Sanghyun Lee
Keyword(s):  
Pushover Analysis ◽  
Degree Of Freedom ◽  
Base System ◽  
Harmonic Load ◽  
Friction Damper ◽  
External Energy ◽  
Design Factor ◽  
Natural Period ◽  
Tightening Force ◽  
Rotary Type

In this study, the shape of a vertical expansion module with a rotary-type damping device is proposed. The external energy dissipation capacity is confirmed through experiments and the performance of the module is simulated. It can be easily applied to high-rise structures, as the module is directly supported by the bearing walls without the need for a separate base system. Additionally, as the damper can be replaced, it is possible to enhance seismic performance even after construction. The simulation results show that the rotary-type damper is more effective in reducing the displacement, shear force, and moment than free and fixed joints. In the pushover analysis of a system modeled using the moment hinge of the rotary damper of the joint, the best response reduction effect is obtained when the yield moment of the hinge is defined as 1% of the frame plastic moment. As a result of the analysis of the multi-degree-of-freedom system considering a harmonic load, we determined that it is efficient for the hinge to yield after the displacement, and the acceleration response of the resonant structure reaches steady state during the installation. In the multi-degree-of-freedom system with slab joints added to the analytical model, the displacement response decreased gradually as the natural period of the structure decreased and the joint increased. This provides evidence that the damper does not affect the overall behavior of the structure. The most important design factor of the rotary-type friction damper, shown through the experiment, is the relationship between the frictional surface and the tightening force of the bolt.

Study of Pushover Analysis on RC Framed Structure with Underground Structure Considering the Effects of Soil Structure Interaction

2020 ◽  
Vol 8 ◽  
pp. 22-29
Author(s):  
Nasala Dongol ◽  
Prachand Man Pradhan ◽  
Suman Manandhar
Keyword(s):  
Soil Structure ◽  
Response Spectrum ◽  
Underground Structure ◽  
Pushover Analysis ◽  
Standard Penetration Test ◽  
Soil Structure Interaction ◽  
Base System ◽  
Building Site ◽  
Structure Interaction ◽  
Fixed Base

This study states that the effects of soil structure interaction on the Reinforced Concrete (RC) framed structures is directly influenced by the soil properties of the site. Here, one preexisting structure is taken for the study. The building is a hospital building with two underground basements. Taking into account the actual soil condition of building site, this study provides idea on the soil structure interaction on the structure The properties of springs are calculated from different standard penetration test (SPT) values, Poisson’s ratio and elasticity of soil along the depth of the soil. Entire soil-foundation-structure system is modelled and analyzed using spring approach. Static analysis, response spectrum analysis and pushover analysis (PA) are done in order to find the variations in natural periods, base shears and deflections of the structures by incorporating soil flexibility as compared to structures with conventional fixed base. Pushover analysis is done to evaluate the performance of the structure when modelled in fixed base and spring base system.

Development of a Single-Degree-of-Freedom Mechanical Model for Predicting Strain-Based Brain Injury Responses

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Lee F. Gabler ◽  
Hamed Joodaki ◽  
Jeff R. Crandall ◽  
Matthew B. Panzer
Keyword(s):  
Brain Injury ◽  
Degree Of Freedom ◽  
Deformation Model ◽  
Maximum Magnitude ◽  
Natural Period ◽  
Single Degree Of Freedom ◽  
Head Kinematics ◽  
Single Degree ◽  
Brain Deformation ◽  
Deformation Mechanics

Linking head kinematics to injury risk has been the focus of numerous brain injury criteria. Although many early forms were developed using mechanics principles, recent criteria have been developed using empirical methods based on subsets of head impact data. In this study, a single-degree-of-freedom (sDOF) mechanical analog was developed to parametrically investigate the link between rotational head kinematics and brain deformation. Model efficacy was assessed by comparing the maximum magnitude of displacement to strain-based brain injury predictors from finite element (FE) human head models. A series of idealized rotational pulses covering a broad range of acceleration and velocity magnitudes (0.1–15 krad/s2 and 1–100 rad/s) with durations between 1 and 3000 ms were applied to the mechanical models about each axis of the head. Results show that brain deformation magnitude is governed by three categories of rotational head motion each distinguished by the duration of the pulse relative to the brain's natural period: for short-duration pulses, maximum brain deformation depended primarily on angular velocity magnitude; for long-duration pulses, brain deformation depended primarily on angular acceleration magnitude; and for pulses relatively close to the natural period, brain deformation depended on both velocity and acceleration magnitudes. These results suggest that brain deformation mechanics can be adequately explained by simple mechanical systems, since FE model responses and experimental brain injury tolerances exhibited similar patterns to the sDOF model. Finally, the sDOF model was the best correlate to strain-based responses and highlighted fundamental limitations with existing rotational-based brain injury metrics.

Synthesis of Multi-Degree-of-Freedom Force-Generating Linkages

1998 ◽  
Author(s):  
R. Randall Soper ◽  
Charles F. Reinholtz ◽  
Stephen L. Canfield
Keyword(s):  
Closed Form ◽  
Analytical Techniques ◽  
Open Loop ◽  
Degree Of Freedom ◽  
Storage Device ◽  
Resistance Force ◽  
External Energy ◽  
Conceptual Foundation ◽  
Closed Form Solutions ◽  
Input Position

Abstract This paper presents the conceptual foundation and analytical techniques for the design of multiple-degree-of-freedom force-generating linkages. Force-generating mechanisms produce a specified quasi-static force or torque as a function of input position with resisting energy supplied to the mechanism from an external energy-storage device, such as a spring or load weight. Multiple-degree-of-freedom force-generating mechanisms provide the tailored resistance force along a design path while incorporating additional mobility, which allows the mechanism to deviate from the path within a local workspace. Although many potential applications for these mechanisms exist, the focus of this research has been on the design of weight-loaded machines for personal strength training, where the additional freedom of motion is valuable for reasons of ergonomic and exercise efficiency. A variety of open- and closed-chain mechanisms are considered as potential candidates for design. Techniques are developed for the closed-form synthesis of simple, two link, open loop chains that are able to produce a specified force component along a prescribed path. This result provides a foundation for designing more useful mechanisms, including doubly weighted symmetric and singly weighted asymmetric 5R linkages. In all cases, closed-form solutions are developed using Burmester-type synthesis procedures and equations of static equilibrium.

Interruption performance design of variable freedom mechanism triggered by electro-mechanical-magnetic coupling

2016 ◽  
Vol 231 (18) ◽  
pp. 3330-3341 ◽  
Author(s):  
Jinghua Xu ◽  
Shuyou Zhang ◽  
Jianrong Tan ◽  
Sheng Hongsheng
Keyword(s):  
Degrees Of Freedom ◽  
Magnetic Coupling ◽  
Radiation Energy ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Coupling Mechanism ◽  
Variable Degree ◽  
Algebraic Equations ◽  
Tightening Force ◽  
Linear Algebraic Equations

Coupling mechanism plays an important role in transmitting, motivating and actuating mechanical functions. However, it is difficult to obtain the transient dynamics performance of mechanism with variable degree of freedom precisely. Therefore, an interruption performance design method of variable freedom mechanism triggered by electro-magneto-thermo coupling is put forward. The Euler-Lagrange partial differential equations of variable freedom mechanism are built using generalized coordinates. Degree of freedom reduction rules are proposed to merge transformation or rotation constraints and obtain the total degrees of freedom of variable freedom mechanism at each transient status. Bivariate interpolating is employed to determine the electro-mechanical-magnetic coupled Lorentz force. Dynamics performance is simulated by iteration of linear algebraic equations using implicit predictor-corrector integration method. The design parameters such as stiffness and pre-tightening force of trigger spring, permissible dimension deviations and hole-shaft fit tolerance are determined and improved using the sensitivity analysis of simulation results. The pneumatic mechanical endurance and thermal infrared temperature rise experiments are accomplished to determine the infrared radiation energy distribution and transient working status of components. It gives an auxiliary thermo-visual approach for transient performance design of coupling mechanism.

Simplified seismic code design procedure for friction-damped steel frames

1999 ◽  
Vol 26 (1) ◽  
pp. 55-71 ◽  
Author(s):  
Yaomin Fu ◽  
Sheldon Cherry
Keyword(s):  
Design Procedure ◽  
Steel Structures ◽  
Lateral Force ◽  
Building Codes ◽  
Degree Of Freedom ◽  
Friction Damper ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Damped System ◽  
Seismic Force

This paper describes the development of a proposed seismic design procedure for friction-damped steel structures, which employs the lateral force provisions used in many modern building codes. Closed-form expressions are first derived that relate the normalized response of a single degree of freedom friction-damped system with the system parameters, such as bracing stiffness ratio, damper slip ratio, and frame member ductility. A parametric analysis is then used to reveal that the seismic displacement of a friction-damped frame can be controlled by combining the frame stiffness with the bracing stiffness of the friction damper component, while the seismic force can be controlled by the damper slip force. A force modification factor (equivalent to the code R-factor) and displacement estimate for a friction-damped system are next determined. The single degree of freedom results are subsequently used to develop expressions for dealing with the multi degree of freedom situation, which permits the seismic lateral force design procedure adopted by many current building codes to be applied to friction-damped systems. The proposed procedure allows the frame response to be controlled so that the displacement can be limited to small magnitudes and the overall structural shape to an essentially straight-line deformation. Design examples illustrate that friction-damped frame systems are economical and offer a better overall response performance than that provided by conventional systems under the design earthquake.Key words: passive energy dissipation system, friction damper, steel frame, design procedure, static analysis.

Seismic Design of Friction-Damped Braced Frames Based on Historical Records

2005 ◽  
Vol 21 (3) ◽  
pp. 761-778 ◽  
Author(s):  
Robert Levy ◽  
Oren Lavan ◽  
Avigdor Rutenberg
Keyword(s):  
Seismic Design ◽  
Phase 1 ◽  
Nonlinear Dynamic Analysis ◽  
Design Procedure ◽  
Seismic Energy ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Two Phase ◽  
Natural Period ◽  
Sdof System

This paper is concerned with the design of friction dampers designed to slip at a predetermined level and dissipate a substantial portion of the seismic energy, leaving the structure practically intact without its members having to yield or buckle. They are appropriate for use in seismic design of new buildings and in retrofitting existing structures. By choosing a practical design requirement rather than minimizing some energy criterion, a novel design procedure attains the stiffness of the individual braces and their displacements at the threshold of activation. The procedure is a two-phase process that uses in Phase 1 an equivalent single-degree-of-freedom (SDOF) system to obtain an optimal natural period of the structure by performing a full nonlinear dynamic analysis for a set of earthquake records. Phase 2 then enforces the same first mode on both the braced and unbraced frames, with the aim of ensuring simultaneous slippage. The procedure was applied to a 10-story steel frame. It yielded a rather technically attractive design of the braces since for close to mean plus standard deviation of the records, the resulting maximum roof displacements fell within the allowable design, as initially constrained to, and simultaneous slip of all braces occurred for most records. This procedure is rather simple in that the main computational effort, i.e., nonlinear analysis needed for Phase 1, is performed on an equivalent SDOF system only, whereas analysis of the multi-degree-of-freedom (MDOF) system is a linear eigenvalue analysis.

A Nonlinear Analysis Method for Performance-Based Seismic Design

2000 ◽  
Vol 16 (3) ◽  
pp. 573-592 ◽  
Author(s):  
Peter Fajfar
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Pushover Analysis ◽  
Degree Of Freedom ◽  
Nonlinear Static Analysis ◽  
Visual Interpretation ◽  
Nonlinear Method ◽  
Equivalent Damping ◽  
N2 Method ◽  
Performance Based Seismic Design

A relatively simple nonlinear method for the seismic analysis of structures (the N2 method) is presented. It combines the pushover analysis of a multi-degree-of-freedom (MDOF) model with the response spectrum analysis of an equivalent single-degree-of-freedom (SDOF) system. The method is formulated in the acceleration-displacement format, which enables the visual interpretation of the procedure and of the relations between the basic quantities controlling the seismic response. Inelastic spectra, rather than elastic spectra with equivalent damping and period, are applied. This feature represents the major difference with respect to the capacity spectrum method. Moreover, demand quantities can be obtained without iteration. Generally, the results of the N2 method are reasonably accurate, provided that the structure oscillates predominantly in the first mode. Some additional limitations apply. In the paper, the method is described and discussed, and it basic derivations are given. The similarities and differences between the proposed method and the FEMA 273 and ATC 40 nonlinear static analysis procedures are discussed. Application of the method is illustrated by means of an example.

Study on Evaluation Method of High-Rise Building Performance by Equivalent Single Degree of Freedom System

2008 ◽  
Vol 400-402 ◽  
pp. 599-605
Author(s):  
Xing Wen Liang ◽  
Li Xin ◽  
Yue Sheng Tong
Keyword(s):  
Evaluation Method ◽  
Demand Curve ◽  
Time History ◽  
Degree Of Freedom ◽  
Nonlinear Time History Analysis ◽  
Elastic Displacement ◽  
Natural Period ◽  
Single Degree Of Freedom ◽  
High Rise ◽  
Single Degree

A performance evaluation method of high-rise buildings is presented, by means of capacity spectra method which allows for higher mode effects. The multi-degree-of-freedom system (MDOF) of each mode is transformed into equivalent single-degree-of-freedom (ESDOF) system, and the ESDOF system is supposed to be elastic perfectly plastic. In elastic range, the equivalent displacement of ESDOF system for each mode is deduced by displacement response spectra based on the natural period, and the structural lateral elastic displacement of each mode could be determined by the corresponding equivalent displacement and mode shape. In inelastic range, according to capacity spectra method, the relationships among demand curve, capacity curve and ductility coefficient are built. The structural performance under moderate or major earthquake is determined by iteration method. The paper illustrates the application of the proposed procedure with an example and attempts to prove its feasibility by nonlinear time-history analysis.

scholarly journals Energy balance analysis in non linear dynamic equivalent systems.

2018 ◽  
Vol 148 ◽  
pp. 03002
Author(s):  
Iturregui Arranz Carlos ◽  
Soria Herrera Jose Manuel ◽  
Muñoz Díaz Ivan ◽  
García Palacios Jaime Higinio
Keyword(s):  
Energy Balance ◽  
Pushover Analysis ◽  
Degree Of Freedom ◽  
Eurocode 8 ◽  
Type I ◽  
Safety Level ◽  
Rc Structures ◽  
Equivalent Damping ◽  
Nonlinear Properties ◽  
New Formulation

The aim of the paper is to present a critical analysis for nonlinear dynamic vibrations. It is applicable to single degree of freedom –SDOF- of reinforced concrete –RC- structures, revealing its multi degree of freedom –MDOF- performance, showing contrast using the balance of energy, using six accelerograms based on type I and II spectrum, according with Eurocode-8. The degradation curve was obtained applying a new formulation, based on the system work and complementary work, into the pushover analysis. A new method incorporating the Bouc-Wen-Baben-Noori theory and global damage was used for the analysis, adding relevance to the: energy balance in its dissipative part, analysis of the structure’s fundamental parameters, relation’s effective period, equivalent damping and global ductility. The powers, energies and works developed are analyzed, creating a precise balance since energy enters selectively. Hence, an equivalent damping containing a viscous and hysteretic part is predictable, accordingly to the variation of the building’s nonlinear properties. Evaluation of the adequateness and safety level are also obtainable. The controlled parameters contrasted with the balance predicts the structure’s MDOF situation, at any moment related with seismic events. This methodology can be used to stablish a systematic control of nonlinearities for other structural schemes.

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