scholarly journals Seismic Damage Detection of Moment Resisting Frame Structures Using Time-Frequency Features

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Dongwang Tao ◽  
Qiang Ma ◽  
Shanyou Li
Keyword(s):  
Damage Detection ◽  
Plastic Hinge ◽  
Superposition Principle ◽  
Seismic Damage ◽  
Transformation Matrix ◽  
Gabor Wavelet ◽  
Plastic Hinges ◽  
Time Frequency ◽  
Moment Resisting Frame ◽  
Moment Resisting

To detect seismic damage of moment resisting frame (MRF) structures, a data-driven method using the fractal dimension (FD) of time-frequency feature (TFF) of structural seismic dynamic responses at measured stories is extended and refined. The TFF is defined as the real part of Gabor wavelet transform of translational interstory displacement, and FD is used to give a quantitative value to describe the calculated TFF. Static condensation method is first used to reduce the degrees-of-freedom (DOFs) of MRF and to express the rotational displacements using translational displacements. For linear MRF, the FDs of TFFs at all stories are the same using the definition of TFF and modal superposition principle. For damaged MRF with plastic hinges at the ends of beams and columns, the force analogy method is implemented to establish transformation matrix from plastic hinge rotations to translational interstory inelastic displacements. Due to the sparseness of the transformation matrix, plastic hinges only generate interstory inelastic displacements, which are low-frequency contents, in the vicinity of plastic hinges. Correspondingly, the FDs of TFFs of interstory displacements with inelastic component are different from the FDs of TFFs of the interstory displacements that do not contain inelastic component. A numerical simulation on a 16-story MRF was conducted. The simulation included 10 cases such as no damage or linear structure, plastic hinges in single-story beams, plastic hinges in single-story columns, plastic hinges in single-story beams and columns, and plastic hinges in multiple story beams and columns. The robustness to measurement noise was also investigated. The seismic damage detection results demonstrated that the proposed method was capable of locating the stories where the plastic hinges occurred.

scholarly journals AN INVESTIGATION OF THE EFFECTIVENESS OF THE FRAMING SYSTEMS IN STEEL STRUCTURES SUBJECTED TO BLAST LOADING

2014 ◽  
Vol 20 (6) ◽  
pp. 767-777 ◽  
Author(s):  
Amy Coffield ◽  
Hojjat Adeli
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Blast Loading ◽  
Steel Structures ◽  
Response Analysis ◽  
Plastic Hinges ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Moment Resisting ◽  
Applied Element Method

The effectiveness of different framing systems for three seismically designed steel frame structures subjected to blast loading is investigated. The three faming systems considered are: a moment resisting frame (MRF), a concentrically braced frame (CBF) and an eccentrically braced frame (EBF). The blast loads are assumed to be unconfined, free air burst detonated 15 ft (4.572 m) from one of the center columns. The structures are modeled and analyzed using the Applied Element Method, which allows the structure to be evaluated during and through failure. Failure modes are investigated through a plastic hinge analysis and member failure comparison. Also, a global response analysis is observed through comparison of roof deflections and accelerations. A conclusion of this research is that braced frames provide a higher level of resistance to the blast loading scenario investigated in this research. Both the CBF and EBF had a smaller number of failed members and plastic hinges compared to the MRF. They also had smaller roof deflection and acceleration. The CBF yielded the fewest number of plastic hinges but the EBF had a slightly fewer number of failed members.

Probabilistic performance-based evaluation of a tall steel moment resisting frame under post-earthquake fires

2016 ◽  
Vol 7 (3) ◽  
pp. 193-216 ◽  
Author(s):  
Negar Elhami Khorasani ◽  
Maria Garlock ◽  
Paolo Gardoni
Keyword(s):  
Elevated Temperatures ◽  
Fire Spread ◽  
Seismic Damage ◽  
Economic Losses ◽  
Limit States ◽  
Content Type ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Steel Moment Resisting Frame ◽  
Performance Based Evaluation

Purpose This paper aims to develop a framework to assess the reliability of structures subject to a fire following an earthquake (FFE) event. The proposed framework is implemented in one seamless programming environment and is used to analyze an example nine-story steel moment-resisting frame (MRF) under an FFE. The framework includes uncertainties in load and material properties at elevated temperatures and evaluates the MRF performance based on various limit states. Design/methodology/approach Specifically, this work models the uncertainties in fire load density, yield strength and modulus of elasticity of steel. The location of fire compartment is also varied to investigate the effect of story level (lower vs higher) and bay location (interior vs exterior) of the fire on the post-earthquake performance of the frame. The frame is modeled in OpenSees to perform non-linear dynamic, thermal and reliability analyses of the structure. Findings Results show that interior bays are more susceptible than exterior bays to connection failure because of the development of larger tension forces during the cooling phase of the fire. Also, upper floors in general are more probable to reach specified damage states than lower floors because of the smaller beam sizes. Overall, results suggest that modern MRFs with a design that is governed by inter-story drifts have enough residual strength after an earthquake so that a subsequent fire typically does not lead to results significantly different compared to those of an event where the fire occurs without previous seismic damage. However, the seismic damage could lead to larger fire spread, increased danger to the building as a whole and larger associated economic losses. Originality/value Although the paper focuses on FFE, the proposed framework is general and can be extended to other multi-hazard scenarios.

scholarly journals Role of Higher-“Mode” Pushover Analyses in Seismic Analysis of Buildings

2005 ◽  
Vol 21 (4) ◽  
pp. 1027-1041 ◽  
Author(s):  
Rakesh K. Goel ◽  
Anil K. Chopra
Keyword(s):  
Seismic Analysis ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Moment Resisting Frame ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Pushover Curve ◽  
Fema 356 ◽  
Direction Opposite

The role of higher-“mode” pushover analyses in seismic analysis of buildings is examined in this paper. It is demonstrated that the higher-“mode” pushover curves reveal plastic hinge mechanisms that are not detected by the first-“mode” or other FEMA-356 force distributions, but these purely local mechanisms are not likely to develop during realistic ground motions in an otherwise regular building without a soft and/or weak story. Furthermore, the conditions necessary for “reversal” of a higher-“mode” pushover curve are examined. It is shown that “reversal” in a higher-“mode” pushover curve occurs after formation of a mechanism if the resultant force above the bottom of the mechanism is in the direction that moves the roof in a direction opposite to that prior to formation of the mechanism. Such “reversal” can occur only in higher-“mode” pushover analyses but not in the pushover analyses for the first-“mode” or other FEMA-356 force distributions. However, the “reversal” in higher-“mode” pushover curves was found to be very rare in several recent investigations that examined behavior of many moment-resisting frame buildings. Included are guidelines for implementing the Modal Pushover Analysis for buildings that display “reversal” in a higher-“mode” pushover curve.

scholarly journals A Review on the Plastic Hinge Characteristics of Beam-Column Joints in RC Moment Resisting Frames

2021 ◽  
Author(s):  
Surya SS ◽  
R Sajeeb
Keyword(s):  
Plastic Hinge ◽  
High Strength ◽  
Joint Interface ◽  
Careful Study ◽  
Plastic Hinges ◽  
Moment Resisting Frames ◽  
Extreme Loads ◽  
Moment Resisting ◽  
Column Joint ◽  
Joint Behavior

The behavior of beam-column joints plays a crucial role in the performance of Reinforced Concrete (RC) moment-resisting frames in earthquake-prone areas. In beam-column joints with high strength concrete and shear reinforcement in joints, the plastic hinge is formed at the beam-column joint interface, which is an undesirable failure mode. Predicting the behavior of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquake plays an important role in assessing maximum stable deformation capacities of framed concrete structures. The present paper reviews the plastic hinge characteristics of beam-column joints of RC moment-resisting frames. A careful study and understanding of joint behavior are essential to arrive at a proper judgment of the design of joints. Various types of joints and the influence of bond strength characteristics, forces acting on joints, reinforcement detailing, and the concept and formation of plastic hinges in the joints are thoroughly reviewed.

scholarly journals Ductility demand for uni-directional and reversing plastic hinges in ductile moment resisting frames

1999 ◽  
Vol 32 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Richard Fenwick ◽  
Raad Dely ◽  
Barry Davidson
Keyword(s):  
Plastic Hinge ◽  
Time History ◽  
Simple Relationship ◽  
Plastic Hinges ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Negative Moment ◽  
Unidirectional Plastic

In a major earthquake the beams in moment resisting frames may develop either reversing or unidirectional plastic hinges. The form of plastic hinge depends upon the ratio of the moments induced by the gravity loading to those induced by the seismic actions. Where this ratio is low the plastic hinges form at the ends of the beams and the sign of the inelastic rotation changes with the direction of sway. These are reversing plastic hinges, and the magnitude of the rotation that they sustained is closely related to the inter-storey displacement. However, when the moment ratio exceeds a certain critical value, unidirectional plastic hinges may form. In this case negative moment plastic hinges develop at the column faces and the positive moment plastic hinges form in the beam spans. As the earthquake progresses the positive and negative inelastic rotations accumulate in their respective zones so that peak values are always sustained at the end of the earthquake. With this type of plastic hinge no simple relationship exists between inter-storey drift and inelastic rotation. Several series of time history analyses have been made to assess the relative magnitudes of inelastic rotation that are imposed on the two forms of plastic hinge. It is found that with design level earthquakes typically the unidirectional plastic hinge is required to sustain 21/ 2 to 4 times the rotation imposed on reversing plastic hinges, with the curvature ductilities ranging up to 140. These values are appreciably in excess of the values measured in tests using standard details. This indicates that in structures where unidirectional plastic hinges may form, the design displacement ductility and or the allowable inter-storey drift should be reduced below the maximum values currently permitted in the New Zealand codes. The problems associated with the formation of unidirectional plastic hinges can be avoided by adding positive moment flexural reinforcement in the mid regions of the beams. By this means the potential positive moment plastic hinges can be restricted to the beam ends.

scholarly journals Evaluation of plastic hinges performance and the elastic stiffness factor of moment-resisting frame structures

2020 ◽  
Vol 1 (3) ◽  
pp. 10-17
Author(s):  
Khosro Zehro ◽  
Shahram Jkhsi
Keyword(s):  
Lateral Displacement ◽  
Structural Parameters ◽  
Plastic Hinge ◽  
Elastic Stiffness ◽  
Base Shear ◽  
Plastic Hinges ◽  
Rc Structures ◽  
Wide Range ◽  
Moment Resisting ◽  
Nonlinear Static

Nowadays, to analyse and determine the maximum seismic lateral displacement for reinforced concrete (RC) structures, the most applicable procedure used by structural engineers is the nonlinear static (pushover) analysis. The nonlinear static procedure (NSP) is a common approach for analysing the seismic performance of construction structures. By directing this procedure, the weak points in each structural member can be examined, and it also determines whether the members are safe or need to rehabilitate. This process defines the level of performance and shear strength under seismic diffusion to construct each element of the structure. The displacement, the base shear, the plastic hinge model, and the effect of the different plan on seismic response of structures has been reported. When concentrating on the RC structures, it requires the ability to conduct lateral resistant force systems, which one of them is commonly known as moment-resisting frames (MRFs). In this paper, three models of RC structures considered for low-, medium-, and high-rise buildings were examined, and each model has been analysed for three different spans. These models have been analysed applying ETABS software by inputting and examining a wide range of structural parameters. A comprehensive study on the pushover curve, performance curve, among others have been performed. The aim of this study is to consider the effect of plastic hinges in various ranges of performance capacities to evaluate the elastic stiffness factor of structures

Stiffening of Moment-Resisting Frame by Precast Concrete Cladding

PCI Journal ◽  
1992 ◽  
Vol 37 (5) ◽  
pp. 80-92 ◽  
Author(s):  
Regina Gaiotti ◽  
Bryan Stafford Smith
Keyword(s):  
Precast Concrete ◽  
Moment Resisting Frame ◽  
Moment Resisting
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