scholarly journals DAMAGE DETECTION OF SHEAR CONNECTORS IN BRIDGE STRUCTURES WITH TRANSMISSIBILITY IN FREQUENCY DOMAIN

2014 ◽  
Vol 14 (02) ◽  
pp. 1350061 ◽  
Author(s):  
JUN LI ◽  
HONG HAO ◽  
YONG XIA ◽  
HONG-PING ZHU
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Measurement Data ◽  
Field Testing ◽  
Damage Level ◽  
Shear Connectors ◽  
Bridge Structures ◽  
Girder Bridge

Shear connectors are generally used to link the slab and girder together in slab-on-girder bridge structures. Damage of shear connectors in such structures will result in shear slippage between the slab and girder, which significantly reduces the load-carrying capacity of bridges. A damage detection approach based on transmissibility in frequency domain is proposed in this paper to identify the damage of shear connectors in slab-on-girder bridge structures with or without reference data from the undamaged structure. The transmissibility, which is an inherent system characteristic, indicates the relationship between two sets of response vectors in frequency domain. Measured input force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at the slab and girder sensor locations by the experimental modal analysis. The transmissibility matrix that relates the slab response to the girder response is then derived. By comparing the transmissibility vectors in undamaged and damaged states, the damage level of shear connectors can be identified. When the measurement data from the undamaged structure are not available, a study with only the measured response data in the damaged state for the condition assessment of shear connectors is also conducted. Numerical and experimental studies on damage detection of shear connectors linking a concrete slab to two steel girders are conducted to validate the accuracy and efficiency of the proposed approach. The results demonstrate that the proposed method can be used to identify shear connector damages accurately and efficiently. The proposed method is also applied to the condition evaluation of shear connectors in a real composite bridge with in-field testing data.

Damage Detection of Shear Connectors Based on Power Spectral Density Transmissibility

2013 ◽  
Vol 569-570 ◽  
pp. 1241-1248 ◽  
Author(s):  
Jun Li ◽  
Hong Hao
Keyword(s):  
Spectral Density ◽  
Damage Detection ◽  
Frequency Response ◽  
Power Spectral Density ◽  
Experimental Studies ◽  
Measurement Data ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Shear Connectors ◽  
Power Spectral

Damage of shear connectors in slab-on-girder structures will result in shear slippage between slab and girder, which significantly reduces the load-carrying capacity of the bridge. This paper proposes a dynamic damage detection approach to identify the damage of shear connectors in slab-on-girder bridges with power spectral density transmissibility (PSDT). PSDT formulates the relationship between the auto-spectral density functions of two responses. Measured impact force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at the slab and girder sensor locations by experimental modal analysis. When measurement data from the undamaged structure are available, PSDT from the slab response to the girder response is derived with the obtained frequency response functions. PSDT matrices in the undamaged and damaged states are directly compared to identify the damage of shear connectors. When the measurement data from the undamaged structure are not available, PSDT matrices from measured response at a reference sensor response to those of the slab and girder in the damaged state can also be used to detect the damage of shear connectors. Experimental studies with a concrete slab supported by two steel girders are conducted to investigate the accuracy and efficiency of the proposed approach. Identification results demonstrated that damage of shear connectors can be identified accurately and efficiently with and without measurement data from the undamaged structure.

scholarly journals Experimental and theoretical investigation of composite truss beams

2018 ◽  
Vol 174 ◽  
pp. 04001
Author(s):  
Jan Bujnak ◽  
Peter Michalek ◽  
Wieslaw Baran
Keyword(s):  
Concrete Slab ◽  
Longitudinal Shear ◽  
Finite Element Analyses ◽  
Structural System ◽  
Local Effects ◽  
Relative Slip ◽  
Shear Connectors ◽  
Design Specifications ◽  
Bridge Structures ◽  
European Standards

The design specifications of composite trusses are only partially included in the European standards. However this construction system can be considered as one of the most economical for building and bridge structures. To create an interaction between steel and concrete, it is necessary to prevent the relative slip at the steel and concrete interface using the shear connectors. But the local effects of a concentrated longitudinal shear force between steel truss chord and concrete slab, as special task, should be appropriately examined. The finite element analyses can be used to investigate numerically this structural system behaviour, exploiting several computer procedures. The experimental research has tested these procedures. The outputs of this study are presented in the paper.

LOCAL EFFECTS OF TRUSS NODE FORCES ON SHEAR CONNECTION IN COMPOSITE TRUSS BEAMS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Josef Machacek ◽  
Martin Charvat
Keyword(s):  
Cross Sections ◽  
Concrete Slab ◽  
Longitudinal Shear ◽  
Limit States ◽  
Shear Connectors ◽  
Shear Connection ◽  
Bridge Structures ◽  
Using Data ◽  
Iteration Analysis ◽  
Connection Design

Design of composite steel and concrete truss girders is discussed, with an emphasis on longitudinal connection of the steel truss and a concrete slab. While a strongly non-uniform distribution of longitudinal shear due to localized force transfer in truss nodes occurs in elastic stages of early loadings, the plastic redistribution follows up to collapse. The former is of primary interest in the design of bridges, class 3 and 4 cross sections, non-ductile shear connection, and serviceability limit states in general. This research clears up the distribution in elastic phases and the process of plastic redistribution by using data of real bridge structures. Wide parametric studies provide insight into important parameters influencing the distribution, such as rigidities of shear connection, rigidities of steel chord and concrete slab, concentration of shear connectors above truss nodes, influence of temperature effects, shrinkage and creep. Design according to Eurocode 4 is discussed together with common procedures used by designers, referring to rather improper/conservative solutions. The necessity of densification of shear connectors above truss nodes is discussed in detail and suggestions for an iteration analysis for reasonable connection design is proposed.

scholarly journals AERODYNAMIC STABILITY OF BRIDGES WITH VARIOUS LEVELS OF STRUCTURAL DAMPING

2021 ◽  
Vol 6 (4) ◽  
pp. 54-62
Author(s):  
Olga Poddaeva ◽  
◽  
Pavel Churin ◽  
Keyword(s):  
Experimental Studies ◽  
Real Life ◽  
Wind Tunnels ◽  
Experimental Unit ◽  
State University ◽  
Structural Damping ◽  
Aerodynamic Stability ◽  
Bridge Span ◽  
Bridge Structures ◽  
Girder Bridge

Introduction: Structural damping is one of the most important parameters affecting the aerodynamic stability of bridge structures. Purpose of the study: We aimed to assess the effect that structural damping of a bridge structure has on its stability in a wind current. Methods: In the course of the study, we performed experimental studies of the aerodynamic stability in typical girder bridge structures (with two and four main girders) with different levels of structural damping, facilitated by a unique experimental unit: Large Research Gradient Wind Tunnel, courtesy of the National Research Moscow State University of Civil Engineering (NRU MGSU). Results: The results of the experimental studies show that, despite the general trend towards the decrease in the amplitude of bridge span structure oscillations as the structural damping level increases, the dependence between these parameters is nonlinear. When providing R&D support in the design of real-life structures, in case it is necessary to increase the aerodynamic stability of the superstructure by increasing the level of structural damping (changing the type of joints in structural elements, using mechanical damping devices), it is recommended to conduct experimental studies in wind tunnels to assess the effectiveness of a given solution.

scholarly journals Experimental evaluation on the structural behavior of truss shear connectors in composite steel-concrete beams

2019 ◽  
Vol 12 (5) ◽  
pp. 1157-1182 ◽  
Author(s):  
W. C. S. BARBOSA ◽  
L. M. BEZERRA ◽  
L. CHATER ◽  
O. R. O. CAVALCANTE
Keyword(s):  
Composite Structures ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Experimental Models ◽  
Concrete Slabs ◽  
Shear Connectors ◽  
Reinforced Concrete Slabs ◽  
Constituent Material ◽  
Steel Composite ◽  
Stud Connector

Abstract The composite structures have great advantages in terms of structural and constructive aspects, with the shear connectors being decisive for obtaining the interaction between the structural elements and for the distribution of the stresses in the structure, taking advantage of the potentiality of each constituent material of the composite structure (steel and concrete). This work, through experimental studies, presents the development of a shear connector (Truss connector) proposed for use in a concrete-steel composite beam. The proposed connector is easy to implement and can serve as a viable alternative to the use of stud or U connectors. It was idealized a connector geometry that would provide low production cost, ease of execution, higher values of resistant load, efficiency as regards the relative sliding resistance between the metal profile and the concrete slab, as well as the efficiency regarding the resistance to the spacing of the slabs in relation to the metal profile (uplift). In order to evaluate the behavior of Truss connectors, 6 experimental models were constructed for push-out tests, 3 with 12.5 mm diameter Truss connectors and 3 with 19.0 mm diameter stud bolt connectors. The behavior of the models was investigated with respect to the loads of rupture, the transversal displacements between the concrete slabs and the relative vertical slide between the reinforced concrete slabs and the metallic profiles of the models. The results of the experimental analyzes provided an overview of the operation of the Truss and stud bolt connectors, with significant results that showed advantages of the Truss connector in relation to the stud connector considering the parameters analyzed in this work.

Non-baseline method for damage detection in truss structures using displacement and strain measurements

2018 ◽  
Vol 22 (3) ◽  
pp. 818-830 ◽  
Author(s):  
Peng Ren ◽  
Zhi Zhou ◽  
Jinping Ou
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Experimental Studies ◽  
Measurement Data ◽  
Element Model ◽  
Truss Structures ◽  
Detection Methods ◽  
Detection Approach ◽  
Potential Development ◽  
System States

Realistic problems restrict the application of many existing structural damage detection methods. Due to the requirement of a comparison between two system states, lack of appropriate baseline data may become one of the limitations to undertake structural health monitoring strategy. This article suggests a non-baseline damage detection approach based on the mixed measurements and the transmissibility concept and demonstrates it in truss structures. The algorithm uses the measurement data from the strains of the truss elements and the displacements of the truss joints, in which the displacements are utilized to estimate the baseline strains based on the transmissibility matrix from an initial finite element model. Wavelet-based damage-sensitive features are extracted from both estimated and measured strains to detect damages of the target elements. Numerical and experimental studies are performed to investigate the feasibility and effectiveness of the proposed approach. It is concluded from the instances that the robustness of the algorithm is realized when handling the measurement noise, modeling errors and the operational condition variability. These permit the potential development of the damage detection method for real structures in site.

The Influence of Slab Concreting Sequence on a Continuous Composite Girder Bridge

2016 ◽  
Vol 691 ◽  
pp. 96-107
Author(s):  
Tomas J. Zivner ◽  
Rudolf B. Aroch ◽  
Michal M. Fabry
Keyword(s):  
Concrete Slab ◽  
Transverse Cross Section ◽  
Slab Thickness ◽  
Slab Width ◽  
Composite Girder ◽  
Steel Members ◽  
Composite Bridge ◽  
Bridge Girder ◽  
Girder Bridge ◽  
Main Girder

This paper deals with the slab concreting sequence and its influence on a composite steel and concrete continuous highway girder bridge. The bridge has a symmetrical composite two-girder structure with three spans of 60 m, 80 m, 60 m (i.e. a total length between abutments of 200.0 m). The horizontal alignment is straight. The top face of the deck is flat. The bridge is straight. The transverse cross-section of the slab is symmetrical with respect to the axis of the bridge. The total slab width is 12 m. The slab thickness varies from 0.4 m on main girders to 0.25 m at its free edges and 0.3075 m at its axis of symmetry. The center-to-center spacing between main girders is 7 m and the slab cantilever on either side is 2.5 m long. Every main girder has a constant depth of 2800 mm and the thicknesses of the upper and lower flanges are variable. The lower flange is 1200 mm wide whereas the upper flange is 1000 mm wide. The two main girders have transverse bracing at abutments and at internal supports and at regular intervals in every span. The material of concrete slab is C35/45 and of steel members S355. The on-site pouring of the concrete slab segments is performed by casting them in a selected order and is done after the launching of the steel two girder bridge. The paper presents several concreting sequences and their influence on the normal stresses and deflections of the composite bridge girder.

Sparse damage detection via the elastic net method using modal data

2021 ◽  
pp. 147592172110219
Author(s):  
Rongrong Hou ◽  
Xiaoyou Wang ◽  
Yong Xia
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Damage Identification ◽  
Measurement Data ◽  
Elastic Net ◽  
Sensitivity Matrix ◽  
Regularization Technique ◽  
Modal Data ◽  
Regularization Techniques ◽  
Net Method

The l1 regularization technique has been developed for damage detection by utilizing the sparsity feature of structural damage. However, the sensitivity matrix in the damage identification exhibits a strong correlation structure, which does not suffice the independency criteria of the l1 regularization technique. This study employs the elastic net method to solve the problem by combining the l1 and l2 regularization techniques. Moreover, the proposed method enables the grouped structural damage being identified simultaneously, whereas the l1 regularization cannot. A numerical cantilever beam and an experimental three-story frame are utilized to demonstrate the effectiveness of the proposed method. The results showed that the proposed method is able to accurately locate and quantify the single and multiple damages, even when the number of measurement data is much less than the number of elements. In particular, the present elastic net technique can detect the grouped damaged elements accurately, whilst the l1 regularization method cannot.

scholarly journals A frequency‐domain approach for damage detection in welded structures

2021 ◽  
Author(s):  
Camilla Ronchei ◽  
Sabrina Vantadori ◽  
Andrea Carpinteri ◽  
Ignacio Iturrioz ◽  
Roberto Issopo Rodrigues ◽  
...  
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Welded Structures ◽  
Frequency Domain Approach

A Frequency-Domain Filtering Technique for Triple Decomposition of Unsteady Turbulent Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 45-51 ◽  
Author(s):  
G. J. Brereton ◽  
A. Kodal
Keyword(s):  
Time Series ◽  
Turbulent Flow ◽  
Frequency Domain ◽  
Measurement Data ◽  
Averaging Technique ◽  
Phase Averaging ◽  
Spectral Estimates ◽  
Improved Performance ◽  
A New Technique ◽  
Flow Variables

A new technique is presented for decomposing unsteady turbulent flow variables into their organized unsteady and turbulent components, which appears to offer some significant advantages over existing ones. The technique uses power-spectral estimates of data to deduce the optimal frequency-domain filter for determining the organized and turbulent components of a time series of data. When contrasted with the phase-averaging technique, this method can be thought of as replacing the assumption that the organized motion is identically reproduced in successive cycles of known periodicity by a more general condition: the cross-correlation of the organized and turbulent components is minimized for a time series of measurement data, given the expected shape of the turbulence power spectrum. The method is significantly more general than the phase average in its applicability and makes more efficient use of available data. Performance evaluations for time series of unsteady turbulent velocity measurements attest to the accuracy of the technique and illustrate the improved performance of this method over the phase-averaging technique when cycle-to-cycle variations in organized motion are present.

Sign in / Sign up

Export Citation Format

Share Document