Sensitivity Analysis based Optimal Seismic Design of Tall Buildings under Story Drift and Base Shear Constraints

2016 ◽  
Author(s):  
Lang Qin ◽  
Xin Zhao
Keyword(s):  
Sensitivity Analysis ◽  
Seismic Design ◽  
Tall Buildings ◽  
Base Shear ◽  
Story Drift

scholarly journals Investigation responses of the diagrid structural system of high-rise buildings equipped with Tuned mass damper using new dynamic method

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Arash Karimipour ◽  
Mansour Ghalehnovi ◽  
Mahmoud Edalati ◽  
Mehdi Barani
Keyword(s):  
Dynamic Method ◽  
Lateral Displacement ◽  
Tall Buildings ◽  
Tuned Mass Damper ◽  
Structural System ◽  
Base Shear ◽  
Structural Behaviour ◽  
High Rise ◽  
Mass Damper ◽  
Story Drift

Due to the shortage of land in cities and population growth, the significance of high rise buildings has risen. Controlling lateral displacement of structures under different loading such as an earthquake is an important issue for designers. One of the best systems is the diagrid method which is built with diagonal elements with no columns for manufacturing tall buildings. In this study, the effect of the distribution of the tuned mass damper (TMD) on the structural responses of diagrid tall buildings was investigated using a new dynamic method. So, a diagrid structural systems with variable height with TMDs was solved as an example of structure. The reason for the selection of the diagrid system was the formation of a stiffness matrix for the diagonal and angular elements. Therefore, the effect of TMDs distribution on the story drift, base shear and structural behaviour were studied. The obtained outcomes showed that the TMDs distribution does not significantly affect on improving the behaviour of the diagrid structural system during an earthquake. Furthermore, the new dynamic scheme represented in this study has good performance for analyzing different systems. 

scholarly journals Parametric Analysis of Rotational Effects in Seismic Design of Tall Structures

2021 ◽  
Vol 11 (2) ◽  
pp. 597
Author(s):  
Milan Sokol ◽  
Rudolf Ároch ◽  
Katarína Lamperová ◽  
Martin Marton ◽  
Justo García-Sanz-Calcedo
Keyword(s):  
Seismic Design ◽  
Parametric Study ◽  
Tall Buildings ◽  
Soil Parameters ◽  
Eurocode 8 ◽  
Tall Structures ◽  
Rotational Components ◽  
Different Types ◽  
Depth Study

This paper uses a parametric study to evaluate the significance of the rotational components of Earth’s motion in a seismic design. The parametric study is based on the procedures included in Eurocode 8, Part 6. Although the answer to the question of when the effects of rotational components are important is quite a complex one and requires a more in-depth study, our aim was to try to assess this question in a relatively quick manner and with acceptable accuracy. The first part of the paper is devoted to derivation of a simple formula that can be used for expressing the importance of rotational components in comparison with the classic seismic design without their usage. The quasi-static analysis, assuming inertial forces, is used. A crucial role plays the shape of the fundamental mode of the vibration. Due to simplicity reasons, well-known expression for estimation of the first eigenmode as an exponential function with different power coefficients that vary for different types of buildings is used. The possibility of changing the soil parameters is subsequently included into the formula for estimation of the fundamental frequency of tall buildings. In the next part, the overall seismic analyses of complex FEM models of 3D buildings and chimneys are performed. The results from those analyses are then compared with those from simplified calculations. The importance of the soil characteristics for determination of whether it is necessary to take into account the rotational effects is further discussed.

Implementing the performance-based seismic design for new reinforced concrete structures: Comparison among ASCE/SEI 41, TBI, and LATBSDC

2021 ◽  
pp. 875529302098196
Author(s):  
Siamak Sattar ◽  
Anne Hulsey ◽  
Garrett Hagen ◽  
Farzad Naeim ◽  
Steven McCabe
Keyword(s):  
Reinforced Concrete ◽  
Los Angeles ◽  
Seismic Design ◽  
Common Ground ◽  
Seismic Analysis ◽  
Tall Buildings ◽  
The United States ◽  
Analysis And Design ◽  
Performance Based Seismic Design ◽  
New Buildings

Performance-based seismic design (PBSD) has been recognized as a framework for designing new buildings in the United States in recent years. Various guidelines and standards have been developed to codify and document the implementation of PBSD, including “ Seismic Evaluation and Retrofit of Existing Buildings” (ASCE 41-17), the Tall Buildings Initiative’s Guidelines for Performance-Based Seismic Design of Tall Buildings (TBI Guidelines), and the Los Angeles Tall Buildings Structural Design Council’s An Alternative Procedure for Seismic Analysis and Design of Tall Buildings Located in the Los Angeles Region (LATBSDC Procedure). The main goal of these documents is to regularize the implementation of PBSD for practicing engineers. These documents were developed independently with experts from varying backgrounds and organizations and consequently have differences in several degrees from basic intent to the details of the implementation. As the main objective of PBSD is to ensure a specified building performance, these documents would be expected to provide similar recommendations for achieving a given performance objective for new buildings. This article provides a detailed comparison among each document’s implementation of PBSD for reinforced concrete buildings, with the goal of highlighting the differences among these documents and identifying provisions in which the designed building may achieve varied performance depending on the chosen standard/guideline. This comparison can help committees developing these documents to be aware of their differences, investigate the sources of their divergence, and bring these documents closer to common ground in future cycles.

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.

Optimal Performance-Based Seismic Design

2012 ◽  
pp. 174-207
Author(s):  
Hamid Moharrami
Keyword(s):  
Sensitivity Analysis ◽  
Performance Evaluation ◽  
Nonlinear Analysis ◽  
Seismic Design ◽  
Optimization Algorithms ◽  
Optimal Performance ◽  
Performance Based Design ◽  
Real Performance ◽  
Performance Based Seismic Design

In this chapter, the reader gets acquainted with the philosophy of performance-based design, its principles, and an overview of the procedures for performance evaluation of structures. The essential prerequisites of optimal performance-based design, including nonlinear analysis, optimization algorithms, and nonlinear sensitivity analysis, are introduced. The methods of nonlinear analysis and optimization are briefly presented, and the formulation of optimal performance-based design with emphasis on deterministic type, rather than probabilistic- (or reliability)-based formulation is discussed in detail. It is revealed how real performance-based design is tied to optimization, and the reason is given for why, without optimization algorithms, multilevel performance-based design is almost impossible.

scholarly journals Numerical Study of Alternative Seismic-Resisting Systems for CLT Buildings

Buildings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 162 ◽  
Author(s):  
Cristiano Loss ◽  
Stefano Pacchioli ◽  
Andrea Polastri ◽  
Daniele Casagrande ◽  
Luca Pozza ◽  
...  
Keyword(s):  
Numerical Study ◽  
High Capacity ◽  
Shear Walls ◽  
Sustainable Urban Development ◽  
Fe Model ◽  
Base Shear ◽  
Interior Space ◽  
Linear Dynamic ◽  
Story Drift ◽  
Uplift Forces

Changes to building codes that enable use of materials such as cross-laminated timber (CLT) in mid- and high-rise construction are facilitating sustainable urban development in various parts of the world. Keys to this are the transition to multi-performance-based design approaches along with fewer limitations on heights or the number of storeys in superstructures constructed from combustible materials. Architects and engineers have increased freedom to apply new design and construction concepts and methods, as well as to combine timber with other structural materials. They also have started to develop wall arrangements that optimise interior space layouts and take advantage of the unique characteristics of CLT. This paper discusses the seismic response of multi-story buildings braced with a CLT core and perimeter shear walls anchored to foundations and floor platforms using modern high-capacity angle brackets and hold-downs, or X-Rad connectors. Linear dynamic finite element (FE) models of seismic responses of superstructures of various heights are presented, based on experimentally determined characteristics of wall anchor connections. Particular attention is given to fundamental vibration periods, base shear and uplift forces on walls, as well as inter-story drift. Discussion of FE model results focuses on structural engineering implications and advantages of using CLT to create shear walls, with emphasis on how choice of wall anchoring connections impacts the possible number of storeys and configurations of superstructures. Employing CLT shear walls with X-Rad or other types of high capacity anchoring connections makes possible the creation of building superstructures having eight and potentially more storeys even in high seismicity regions. However, it is important to emphasise that proper selection of suitable arrangements of shear walls for CLT buildings depends on accurate representation of the semi-rigid behaviors of anchoring connections. The linear dynamic analyses presented here demonstrates the need during engineering seismic design practices to avoid use of FE or other design models which do not explicitly incorporate connection flexibilities while estimating parameters like fundamental periods, base shear and uplift forces, as well as inter-story drift.

scholarly journals Application of Modal-Displacement Based Design Method to Multi-Story Timber Blockhaus Structures

2020 ◽  
Vol 10 (11) ◽  
pp. 3889
Author(s):  
Martina Sciomenta ◽  
Vincenzo Rinaldi ◽  
Chiara Bedon ◽  
Massimo Fragiacomo
Keyword(s):  
Design Method ◽  
Fe Model ◽  
Structural Elements ◽  
Base Shear ◽  
Shear Loads ◽  
Story Drift ◽  
Displacement Based ◽  
Technical Interest ◽  
Wooden Structures

Structures under seismic excitation undergo different inter-story drift levels that can be associated to damage of both structural and non-structural elements, and thus to the expected losses. The Modal-Displacement Based Design (DBD) procedure, in this regard, has been developed to fix major issues of Force Based Design (FBD) approaches, thus to design multi-story buildings in which the inter-story drift can allow one to control damage mechanisms. In this paper, the conventional Modal-DBD methodology is applied to multi-story timber buildings constructed using the Blockhaus technology. Given their intrinsic geometrical and mechanical features (i.e., stacking of logs, door/window openings, gaps and friction mechanisms, etc.), dedicated methods of analysis are required for them, compared to other wooden structures. A three-story case-study Blockhaus system of technical interest is thus presented for the assessment of Modal-DBD calculation steps. As shown, special care must be spent for the selection of convenient inter-story drift limits that in general should reflect the characteristics of the examined structural typology. The backbone parameters are thus collected for each shear-wall composing the 3D Blockhaus building, based on refined Finite Element (FE) analyses of separate log-walls. The overall results of the Modal-DBD process are thus finally assessed by means of a Push-Over (PO) analysis, carried out on a simplified 3D FE model of the examined multi-story structure. The comparison of FE predictions, as shown, demonstrates that reliable estimates can be obtained when the Modal-DBD procedure is applied to timber Blockhaus systems. In particular, base shear loads can be estimated with good accuracy, while the corresponding top displacements are slightly overestimated (with up to +10%–14% the expected values, for the collapse prevention performance level).

Nonlinear Dynamic Analysis of Prefabricated Concrete Shear Wall Structure under Seismic Excitation

2017 ◽  
Vol 873 ◽  
pp. 259-263
Author(s):  
Hao Zhang ◽  
Zi Hang Zhang ◽  
Yong Qiang Li
Keyword(s):  
Finite Element ◽  
Kinematic Hardening ◽  
Nonlinear Dynamic Analysis ◽  
Shear Wall ◽  
Seismic Excitation ◽  
Wall Structure ◽  
Base Shear ◽  
Wall Structures ◽  
Story Drift

The dynamic behavior of the prefabricated and cast in situ concrete shear wall structures subjected to seismic loading is investigated by finite element method. This paper adopted a prefabricated concrete shear wall in a practical engineering. The Precise finite element models of prefabricated and cast in situ concrete shear wall were established respectively by ABAQUS. The damaged plasticity model of concrete and kinematic hardening model of reinforcing steel were used. The top displacement, top acceleration, story drift ratio and base shear forceof prefabricated and cast in situ concrete shear wall under different seismic excitation were compared and analyzed. The earthquake resistant behaviorsof the two kinds of structuresare analyzed and compared. Results show that the performances of PC structure were equal to the cast-in-situ ones.

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