scholarly journals Seismic Response of 3D Steel Buildings considering the Effect of PR Connections and Gravity Frames

2014 ◽  
Vol 2014 ◽  
pp. 1-13
Author(s):  
Alfredo Reyes-Salazar ◽  
Edén Bojórquez ◽  
Achintya Haldar ◽  
Arturo López-Barraza ◽  
J. Luz Rivera-Salas
Keyword(s):  
Seismic Analysis ◽  
Three Dimensional ◽  
Structural Response ◽  
Steel Buildings ◽  
Three Dimensional Model ◽  
Structural Resistance ◽  
Moment Resisting ◽  
Plane Frames ◽  
Partially Restrained ◽  
Gravity Frames

The nonlinear seismic responses of 3D steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are studied explicitly considering the contribution of the IGF. The effect on the structural response of the stiffness of the beam-to-column connections of the IGF, which is usually neglected, is also studied. It is commonly believed that the flexibility of shear connections is negligible and that 2D models can be used to properly represent 3D real structures. The results of the study indicate, however, that the moments developed on columns of IGF can be considerable and that modeling buildings as plane frames may result in very conservative designs. The contribution of IGF to the lateral structural resistance may be significant. The contribution increases when their connections are assumed to be partially restrained (PR). The incremented participation of IGF when the stiffness of their connections is considered helps to counteract the no conservative effect that results in practice when lateral seismic loads are not considered in IGF while designing steel buildings with PMRF. Thus, if the structural system under consideration is used, the three-dimensional model should be used in seismic analysis and the IGF and the stiffness of their connections should be considered as part of the lateral resistance system.

scholarly journals Response Quantities of Framed Buildings under Dynamic Excitation

2019 ◽  
Vol 8 (11) ◽  
pp. 3798-3804
Keyword(s):  
Seismic Analysis ◽  
Structural Response ◽  
Base Shear ◽  
Response Factors ◽  
Analysis And Design ◽  
Dynamic Excitation ◽  
Combination Methods ◽  
Time Period ◽  
Moment Resisting ◽  
Seismic Forces

Seismic analysis of structure is employed to make the structure enable to resist the seismic forces and perform against the factors causing the failure of the structure under dynamic excitation. Among various response factors, the base shear and time period of buildings are predominant factors used in the analysis and design of the structure. The prime objective of the paper is to present an analytical study on non-linear seismic analysis of moment resisting framed buildings (as per Indian code IS1893 – 2016) to evaluate the base shear of different configurations of buildings according to different mode combination methods. The obtained results have been presented the comparative analysis of different combination methods. The paper also presents the evaluated results in the form of the time period values of the different buildings depending upon variation in its configuration. As a result, the responses of multistoried moment-resisting framed buildings have been evaluated for various models of considered buildings based on different mode combination methods, and the results of obtained responses have been analyzed in a comparative manner to understand the behaviour of buildings under various methods and configuration conditions. The work presented in the paper can support to develop better understanding of structural response and efficient designing of structures.

scholarly journals Three-dimensional numerical and experimental study of fracture saturation in panel paintings

2021 ◽  
Author(s):  
Mohammad Yaghoub Abdollahzadeh Jamalabadi ◽  
Noemi Zabari ◽  
Łukasz Bratasz
Keyword(s):  
Three Dimensional ◽  
Structural Response ◽  
Drying Shrinkage ◽  
Paint Layer ◽  
Three Dimensional Model ◽  
Crack Patterns ◽  
Panel Painting ◽  
Complex Crack ◽  
Wood Grain ◽  
Panel Paintings

AbstractPanel paintings—complex multi-layer structures consisting of wood support and a paint layer composed of a preparatory layer of gesso, paints, and varnishes—are among the category of cultural objects most vulnerable to relative humidity fluctuations and frequently found in museum collections. The current environmental specifications in museums have been derived using the criterion of crack initiation in an undamaged, usually new gesso layer laid on wood. In reality, historical paintings exhibit complex crack patterns called craquelures. The present paper analyses the structural response of a paint layer with a virtual network of rectangular cracks under environmental loadings using a three-dimensional model of a panel painting. Two modes of loading are considered—one induced by one-dimensional moisture response of wood support, termed the tangential loading, and the other isotropic induced by drying shrinkage of the gesso layer. The superposition of the two modes is also analysed. The modelling showed that minimum distances between cracks parallel to the wood grain depended on the gesso stiffness under the tangential loading. Despite a nonzero Poisson’s ratio, gesso cracks perpendicular to the wood grain could not be generated by the moisture response of the wood support. The isotropic drying shrinkage of gesso produced cracks that were almost evenly spaced in both directions. The modelling results were cross-checked with crack patterns obtained on a mock-up of a panel painting exposed to several extreme environmental variations in an environmental chamber.

Seismic Fragility Analysis of MRFs with PR Bolted Connections Using IDA Approach

2018 ◽  
Vol 763 ◽  
pp. 678-685 ◽  
Author(s):  
Emanuele Brunesi ◽  
Roberto Nascimbene ◽  
Gian Andrea Rassati
Keyword(s):  
Three Dimensional ◽  
Seismic Intensity ◽  
Structural Safety ◽  
Damage State ◽  
Steel Moment Resisting Frames ◽  
Existing Structures ◽  
Moment Resisting ◽  
Damage States ◽  
Structure Height ◽  
Partially Restrained

Partially restrained (PR) bolted beam-to-column connections are a promising typology of connection in modern steel moment resisting frames (MRFs). Both high-fidelity three-dimensional solid models and mechanics-based idealisations have been extensively explored in order to investigate the behaviour of this attractive solution, applicable both to new construction and to retrofitting of existing structures. Despite this, structural safety has been probabilistically assessed and controlled in a relatively few cases, thus neglecting characterisation, modelling and propagation of uncertainties. As such, this paper moves from a deterministic to a probabilistic framework, proposing fragility models at multiple damage states for low-and medium-rise MRF structures with T-stub and top-and-seat angle connections which may be applied for seismic risk assessment and management. After validation against past experimental data, use was made of component-based modelling to reproduce the seismic response of these PR bolted connection systems within planar MRFs designed for earthquake resistance in accordance with current European rules. A set of 44 records scaled at increasing seismic intensity was considered to perform a series of incremental dynamic analyses (IDAs). Fragility functions for each damage state of interest were then derived and compared. The analysis results show the influence of connection typology and structure height.

Failure progression resistance of a generic steel moment-resisting frame under beam-removal scenarios

2017 ◽  
Vol 8 (3) ◽  
pp. 308-325 ◽  
Author(s):  
Farshad Hashemi Rezvani ◽  
Behrouz Behnam ◽  
Hamid Reza Ronagh ◽  
M. Shahria Alam
Keyword(s):  
Progressive Collapse ◽  
Structural Response ◽  
Safety Level ◽  
Content Type ◽  
Steel Moment Resisting Frames ◽  
Beam Elements ◽  
Structural Resistance ◽  
Moment Resisting ◽  
A Chain ◽  
Design Earthquake

Purpose The purpose of this paper is to determine the failure progression resistance of the steel moment-resisting frames subjected to various beam-removal scenarios after application of the design earthquake pertinent to the structure by investigating a generic eight-story building. Design/methodology/approach The structure is first pushed to arrive at a target roof displacement corresponding to life safety level of performance. To simulate the post-earthquake beam-removal scenario, one of the beam elements is suddenly removed from the structure at a number of different positions. The structural response is then evaluated by using nonlinear static and dynamic analyses. Findings The results show that while no failure is observed in all of the scenarios, the vulnerability of the upper stories is much greater than that of the lower stories. In the next step, the structural resistance to such scenarios is determined. The results confirm that for the case study structure, at most, the resistance to failure progression in upper stories is 58 percent more than that of lower stories. Originality/value Failure and fracture of beam-to-column connections resulting in removal of beam elements may lead to a chain of subsequent failures in other structural members and eventually lead to progressive collapse in some cases. Deficiency in design or construction process of structures when combined by application of seismic loads may lead to such an event.

A Three-Dimensional Rigid-Body Model for Seismic Analysis of the Pebble-Bed HTR Graphite Core Structure

2013 ◽  
Author(s):  
Chuan Zeng ◽  
Haitao Wang
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Structural Integrity ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Computer Code ◽  
Seismic Load ◽  
Three Dimensional Model ◽  
Pebble Bed ◽  
Rigid Body Model

Graphite plays an important role in the pebble-bed high temperature gas-cooled reactors (HTR) as moderator, reflector as well as internal structural material. The HTR core consists of a large number of graphite bricks interconnected with keys. It is required that the structural integrity of the HTR core be maintained when subjected to the seismic load. Hence it is important from the viewpoint of seismic design to investigate the seismic responses of the graphite bricks. Considering the pebble-bed HTR has various graphite shapes, a generalized three-dimensional model with the associated computer code is developed to treat these interconnected graphite bricks with arbitrary shapes. In this model, each brick is treated as a rigid body with six degrees-of-freedom: three translational displacements and three rotations around the brick center of gravity. A nonlinear spring dashpot model is applied to present the collision between adjacent bricks and the interaction forces through the key systems. In the numerical tests, the code is verified by comparing predicted responses with exact solutions for two cases and good agreement is observed. The model is then used for the dynamic analysis of the side reflectors of the pebble-bed HTR core under a given seismic load. The calculated response behaviour of the side reflector column is summarized and discussed.

Numerical implementation of variable friction sliding base isolators and preliminary experimental results

2020 ◽  
Vol 36 (2) ◽  
pp. 767-787
Author(s):  
Tianye Yang ◽  
Paolo M Calvi ◽  
Richard Wiebe
Keyword(s):  
Base Isolation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Structural Response ◽  
Time History ◽  
Experimental Results ◽  
Vertical Coupling ◽  
Moment Resisting ◽  
Variable Friction ◽  
Nonlinear Time History

The development of variable friction base isolation systems (VFSs) is the object of an ongoing international research project that involves extensive numerical and experimental activities. This article presents some of the recent numerical developments carried out as part of this project. More specifically, a three-dimensional (3D) variable friction (VF) element is formulated and implemented into OpenSees, providing the foundation for studying structural response in the context of nonlinear time history (NLTH) analysis. The element implementation captures the bearing bidirectional horizontal response along with horizontal–vertical coupling effects. Response predictions obtained using this newly implemented element are compared with the experimental results obtained from testing a full-scale VFS prototype, showing promising results. Finally, a demonstrative numerical study is carried out in which a steel moment resisting frame (MRF) structure, isolated using VFSs, is analyzed via NLTH analyses.

scholarly journals Optimal Design of Earthquake-Resistant Buildings Based on Neural Network Inversion

2021 ◽  
Vol 11 (10) ◽  
pp. 4654
Author(s):  
Carlo Calledda ◽  
Augusto Montisci ◽  
Maria Cristina Porcu
Keyword(s):  
Neural Network ◽  
Optimal Design ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Structural Response ◽  
Time History ◽  
Optimal Choice ◽  
Design Parameters ◽  
Earthquake Resistant ◽  
Non Linear

An effective seismic design entails many issues related to the capacity-based assessment of the non-linear structural response under strong earthquakes. While very powerful structural calculation programs are available to assist the designer in the code-based seismic analysis, an optimal choice of the design parameters leading to the best performance at the lowest cost is not always assured. The present paper proposes a procedure to cost-effectively design earthquake-resistant buildings, which is based on the inversion of an artificial neural network and on an optimization algorithm for the minimum total cost under building code constraints. An exemplificative application of the method to a reinforced-concrete multi-story building, with seismic demands corresponding to a medium-seismicity Italian zone, is shown. Three design-governing parameters are assumed to build the input matrix, while eight capacity-design target requirements are assigned for the output dataset. A non-linear three-dimensional concentrated plasticity model of the structure is implemented, and time-history dynamic analyses are carried out with spectrum-consistent ground motions. The results show the promising ability of the proposed approach for the optimal design of earthquake-resistant structures.

scholarly journals Optimum Design of TMD System for Tall Buildings

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Ahmed Abdelraheem Farghaly ◽  
Mahmoud Salem Ahmed
Keyword(s):  
Three Dimensional ◽  
Design Procedure ◽  
Structural Response ◽  
Time History ◽  
Tall Buildings ◽  
Three Dimensional Model ◽  
Seismic Excitations ◽  
History Analysis ◽  
Mass Damper ◽  
Dynamic Excitations

As tall buildings keep becoming taller, they become more susceptible to dynamic excitations such as wind and seismic excitations. In this paper, design procedure and some current applications of tuned mass damper (TMD) are discussed. A symmetrical moment resistance frame (MRF) twenty storey three-dimensional model were modeled in SAP2000 and a TMD was placed on its top and through it to study its effects on the structural response due to seismic excitations and using time history analysis with and without the TMD. The study indicates that the response of structure such as storey displacements and shear force of columns can be dramatically reduced by using TMD (groups of TMDs) devices especially with a specific arrangement in the model. The study illustrates the group of four TMDs distributed on the plan (interior) which can be effective as R.C. core shear wall.

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