A Damage Analysis of Steel-Concrete Composite Beams Via Dynamic Methods: Part II. Analytical Models and Damage Detection

2003 ◽  
Vol 9 (5) ◽  
pp. 529-565 ◽  
Author(s):  
Michele Dilena ◽  
Antonino Morassi
Keyword(s):  
Damage Detection ◽  
Dynamic Behavior ◽  
Concrete Slab ◽  
Composite Beams ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Analytical Models ◽  
Reinforced Concrete Slab ◽  
Dynamic Methods ◽  
Positive Results

This paper is the second part of an experimental-analytical investigation on the dynamic behavior of damaged steel-concrete composite beams. In the first part of the research, we presented and discussed the experimental results of a comprehensive series of dynamic tests performed on composite beams with damage in the connection. Experimental observations suggested the formulation of a composite beam analytical model, where the strain energy density of the connection also includes an energy term associated to the occurrence of relative transversal displacements between the reinforced concrete slab and the steel beam. A comparison with experimental results shows that the model enhances accuracy in describing the undamaged state of composite beams and that it is also appropriate to accurately predict the dynamic behavior under damaged conditions. A damage detection technique based on the measurement of variation in the first flexural frequencies was then applied to the suggested model and gave positive results.

A Damage Analysis of Steel-Concrete Composite Beams Via Dynamic Methods: Part I. Experimental Results

2003 ◽  
Vol 9 (5) ◽  
pp. 507-527 ◽  
Author(s):  
Antonino Morassi ◽  
Luigi Rocchetto
Keyword(s):  
Damage Identification ◽  
Concrete Slab ◽  
Dynamic Test ◽  
Flexural Vibration ◽  
High Sensitivity ◽  
Composite Beams ◽  
Experimental Results ◽  
Reinforced Concrete Slab ◽  
Dynamic Methods ◽  
Induced Changes

This paper is an experimental investigation on damage-induced changes in modal parameters of steel-concrete composite beams subject to small vibrations. Dynamic tests have been performed on two pairs of composite beams, whose connections have different linear densities, and three damage configurations for each beam have been analyzed. Damage was induced by removing concrete around some elements connecting the steel beam and the reinforced concrete slab and consequently causing a lack of structural solidarity between the two beams. Experiments revealed that: (i) unlike axial frequencies, flexural frequencies show a rather high sensitivity to damage and therefore can be considered as a valid indicator upon a diagnostic analysis; (ii) induced damage causes the nodes of flexural vibration modes to displace towards the damaged area; (iii) in addition to hindering relative sliding on the concrete-steel interface, the elements connecting the slab and the metallic beam play a key role in reducing transversal motions between the two beams. These experimental results were crucial to outline an accurate analytical model of the dynamic behavior of composite beams with damaged connectors and to formulate a diagnostic problem from dynamic test data. Part II of this research will deal with mechanical modeling of damaged composite beams and damage identification.

Experimental and Analytical Investigation on Spaghetti Problem

2001 ◽  
Author(s):  
Yoshimasa Komaki ◽  
Nobuyuki Kobayashi ◽  
Masahiro Watanabe
Keyword(s):  
Dynamic Behavior ◽  
Multibody Dynamics ◽  
Constant Velocity ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Flexible Beam ◽  
Gap Size ◽  
Lateral Vibration ◽  
Elastic Wall ◽  
Pulling Velocity

Abstract The dynamic behavior of the flexible beam, which is pulled into the slit of the elastic wall with a constant velocity, is discussed with multibody dynamics formulation and experiments. The vibration of the free tip of a flexible beam increases rapidly as pulling into the slit, and this behavior is called “Spaghetti Problem”. The effect of gap size of the slit on the behavior of Spaghetti Problem is especially focused. Dynamic behavior of the beam is simulated numerically and examined the accuracy of the presented formulation by changing the gap size and the pulling velocity of the beam as parameters. It is clarified that the presented modeling method simulates the experimental results quite well, and the gap size and the pulling velocity influence the increase of the lateral vibration near the inlet of the slit.

Vibration of Steel–Concrete Composite Beams Using the Timoshenko Beam Model

2005 ◽  
Vol 11 (6) ◽  
pp. 829-848 ◽  
Author(s):  
Stefan Berczyński ◽  
Tomasz Wróblewski
Keyword(s):  
Dynamic Behavior ◽  
Timoshenko Beam ◽  
Beam Theory ◽  
Composite Beams ◽  
Free Vibrations ◽  
Timoshenko Beam Theory ◽  
Analytical Models ◽  
Beam Model ◽  
Euler Beam ◽  
Flexural Vibrations

In this paper we present a solution of the problem of free vibrations of steel–concrete composite beams. Three analytical models describing the dynamic behavior of this type of constructions have been formulated: two of these are based on Euler beam theory, and one on Timoshenko beam theory. All three models have been used to analyze the steel–concrete composite beam researched by others. We also give a comparison of the results obtained from the models with the results determined experimentally. The model based on Timoshenko beam theory describes in the best way the dynamic behavior of this type of construction. The results obtained on the basis of the Timoshenko beam theory model achieve the highest conformity with the experimental results, both for higher and lower modes of flexural vibrations of the beam. Because the frequencies of higher modes of flexural vibrations prove to be highly sensitive to damage occurring in the constructions, this model may be used to detect any damage taking place in such constructions.

Experimental Modal Analysis of Steel Concrete Composite Beams with Partially Damaged Connection

2004 ◽  
Vol 10 (6) ◽  
pp. 897-913 ◽  
Author(s):  
Michele Dilena ◽  
Antonino Morassi
Keyword(s):  
Damage Detection ◽  
Structural Model ◽  
Strong Dependence ◽  
Composite Beams ◽  
Detection Techniques ◽  
Modal Damping ◽  
Dynamic Methods ◽  
Experimental Errors ◽  
Four Levels ◽  
Intrinsic Feature

One of the main difficulties connected with the use of dynamic methods for damage detection in structures lies in the small sensitivity of the dynamic parameters to damage. This is an intrinsic feature of structural diagnostics based on dynamic data and represents a source of important indeterminacy, such as the strong dependence of the results of damage detection techniques on the experimental errors and on the accuracy of the structural model that is chosen to interpret measurements. These facts are nowadays well known for simple structural systems, such as single beams or frames, but still are not completely clarified for more complicated structures. In this paper we present and discuss the results of an experimental investigation on the sensitivity of modal parameters of steel-concrete composite beams with partially damaged connection. Dynamic tests were performed on two pairs of composite beams, whose connecdons have different linear densities, and four damage configurations for each beam were analyzed. Damage corresponds to a symmnetric notch of increasing depth induced by saw-cutting one end-connector of the composite beam. Natural frequencies and modal damping of the lower axial and flexural modes were assessed for the undamaged configuration and the four levels of damage. Flexural vibrating modes were assessed up to the fourth-order mode.

Utilization of partial end restraint in bridge strengthening

1994 ◽  
Vol 21 (5) ◽  
pp. 836-846
Author(s):  
F. Wayne Klaiber ◽  
Terry J. Wipf ◽  
Rula B. Abu-Kishk
Keyword(s):  
Composite Structures ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Analytical Models ◽  
Finite Element Analyses ◽  
Test Beam ◽  
Bridge Model ◽  
Bridge Strengthening ◽  
End Restraint ◽  
Concrete Deck

The purpose of this investigation is to determine a technique for increasing the capacity of bridges to accommodate today's increase in loading. Strengthening existing steel stringers in composite, steel-beam, concrete-deck bridges by providing partial end restraint is shown to be feasible. The research program included a review of existing literature, testing of a full-scale bridge beam and a 1/3-scale bridge model, and finite-element analyses of the restraint brackets, the test beam, and the model bridge. Analytical and experimental results of this investigation are presented, as well as results from an analytical investigation of the bridge model when subjected to various degrees of end restraint. Six different degrees of end restraint were examined. The achieved percent reductions ranged from 12% to 26% for midspan strains, 20% to 30% for midspan deflections, and 10% to 32% for beam end rotations. The correlation between the analytical and experimental results verified the basic design assumptions; thus, the analytical models can be used for determining the location and the degree of end restraint required to strengthen an existing bridge. Key words: bridges, girder, composite structures, tests, models, strengthening, rehabilitation, restraint.

scholarly journals Serviceability limit state of two-way reinforced concrete slab strengthened with different techniques

2018 ◽  
Vol 162 ◽  
pp. 04001
Author(s):  
Eyad Sayhood ◽  
Ammar Ali ◽  
Zahraa Sharhan
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Limit State ◽  
Experimental Results ◽  
Bottom Surface ◽  
Reinforced Concrete Slab ◽  
Near Surface ◽  
Reinforced Concrete Slabs ◽  
Concrete Layer ◽  
Near Surface Mounted

The experimental results for service load of sixteen simply supported two way reinforced concrete slabs under the action of concentrated patch load were determined based on the amount of permissible deflections and the crack widths.All the slabs had the same overall dimensions and flexural steel reinforcement. Five types of strengthening were adopted. The first and second methods include applying either near surface mounted (NSM) or near reinforcement mounted (NRM) ferrocement layers. While the third method includes applying a concrete layer reinforced with welded wire fabric mesh of various diameters. The fourth and fifth methods include fixing CFRP rods and laminates, respectively, on the bottom surface of slabs. Strengthening techniques were applied on the bottom surface of fifteen slab specimens. In addition, a control slab specimen without any strengthening was used for the purpose of comparison. The calculated results for ultimate loads based on serviceability requirements (deflection and crack width according to both ACI and BS formulae) were lower than the experimental results.

scholarly journals Effective Flange Width for Composite Steel Beams

2011 ◽  
Vol 7 (2) ◽  
pp. 28 ◽  
Author(s):  
T. Salama ◽  
H.H. Nassif
Keyword(s):  
Concrete Slab ◽  
Composite Beams ◽  
Analytical Investigation ◽  
Steel Beams ◽  
Limit States ◽  
Composite Action ◽  
Shear Connectors ◽  
Slab Width ◽  
Effective Flange Width ◽  
Composite Steel

 The effective flange width is a concept proposed by various codes to simplify the computation of stress distribution across the width of composite beams. Questions have been raised as to the validity of the effective slab width provisions, since they have a direct effect on the computed ultimate moment as well as serviceability limit states such as deflection, fatigue, and overloading. The objective of this paper is to present results from an experimental and analytical investigation to determine the effective slab width in steel composite beams. The Finite Element Method (FEM) was employed for the analysis of composite steel-concrete beams having variable concrete flange widths. Results were compared to those from tests performed on eight beams loaded to failure. Beam test specimens had variable flange width and various degrees of composite action (shear connectors). The comparison presented in terms of the applied load versus deflection, and strain in the concrete slab show that the AISC-LRFD code is conservative and underestimates the width active. Based on a detailed parametric study an equation for the calculation of the effective flange width is recommended. 

scholarly journals Optimal Design of Steel–Concrete Composite Beams Strengthened under Load

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4715
Author(s):  
Piotr Szewczyk ◽  
Maciej Szumigała
Keyword(s):  
Numerical Models ◽  
Concrete Slab ◽  
Plate Thickness ◽  
Steel Part ◽  
Composite Beams ◽  
Steel Plates ◽  
Reinforced Concrete Slab ◽  
Recoverable Strain ◽  
Bending Capacity ◽  
Optimum Solution

This paper presents results of numerical analysis and experimental research on strengthening of steel–concrete composite beams. Studied members consisted of IPE200 I-beam and 90 × 700 mm reinforced concrete slab. The steel part of the section was strengthened by welding additional steel plates at the bottom. The study was performed for plate thickness ranging between 6 to 22 mm. Spatial FEM models were developed to account for material and geometric nonlinearities and for stress and post-welding strain. Proposed numerical models were experimentally validated. One aim was to find an optimum solution which would minimize cost and maximize bending capacity. To achieve this, energy parameters available in numerical simulations were reviewed and analyzed. Recoverable strain energy value determined in Abaqus was used to find the optimum solution.

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