This paper presents an energy analysis of the free vibration problem for rectangular plates with arbitrary boundary conditions. We propose to evaluate the free vibration characteristics of rectangular plates using the strain energy and the kinetic energy. The analysis procedure is based on the linear, small-strain three-dimensional (3-D) theory of elasticity. The B-spline Ritz method is used to analyze the eigenfrequency and the eigenmode of rectangular plates. The effects of thickness-to-length ratio, mode number and boundary condition on the eigenfrequency, eigenmode, strain energy and kinetic energy of rectangular plates are investigated in detail.
It is need to maintain the durability of concrete structure from the viewpoint of the proper control of maintenance. The ultrasonic method which is one of nondestructive tests is utilized as the degradation evaluation of concrete structure. When the ultrasonic method is applied to an inhomogeneous material, the ultrasonic wave intricately passes around the degraded parts of the material. Though the intricate change of the wave is considered to depend on the types of degradation, there are few researches surveying the relationship between the change of the wave and the types of degradation. Thus, in this study, numerical analyses are conducted with considering various types of degradation so as to discuss their influence to the wave propagation of an ultrasonic wave. It is clarified that the wave change is correlated to the types of degradation.
Structures stacking up concrete blocks are the gravity style structure using the weight. In order to improve the earthquake resistance, increasing the weight is generally conducted. One of the authors proposed a reinforced structure to improve the earthquake resistance by installing a rubber mat between the concrete blocks. It can be expected that this method could control the vibration characteristics and shift the resonance point of structure and spectrum of earthquake. In this study, efficiency and adequacy of the proposed structure has been simulated by a discrete finite element model with frictional modeling. The accuracy of the numerical simulation has been validated with experimental tests. After the test, we conducted an earthquake response analysis in a real size structure.
Falling rock protection with buffer devices had been proposed, and it had shown that the behavior of this protection can be expressed by dynamic response analysis. However, the dynamic response analysis require much effort. On the other hand, important quantities of falling rock protection with buffer devices are maximum deflection of protection and maximum sliding displacements of the inside wire of buffer devices. In this paper, new numerical method is prospoed. In this method, these important quantities are obtained by static analysis that is an equivalent result of dynamic response analysis.
In this study, to clarify properties that tsunami wave force affect bridge superstructure which is generally applied to expressway bridges, waterway experiments and numerical analyses were conducted. In the waterway experiment, some tsunami waves which have maximum 10m height and 6.4m/sec water flow speed in actual scale were generated and characteristics of tsunami wave force acting on standard box-girder bridge were clarified. In the numerical analysis, to reproduce and evaluate results of waterway experiments, CFD (Computational Fluid Dynamics) with VOF method were carried out and applicability of this analysis method was confirmed.
Bridge Redundancy Evaluation is getting more attention in both designing new highway bridges and repairing or retrofitting old bridges after several bridge collapses or failure incidents happened around the world in recent years. This study is tempted to evaluate effects of secondary members on redundancy of three-span composite twin I-girder bridge. Two types of secondary members were studied including I-shape transverse beams and L-shape X-type bottom lateral bracing. Results show that three-span composite twin I-girder bridge can be considered as redundant. The redundancy level can be increased by adding bottom X-type lateral bracing. I-shape transverse beams alone is found not effective in increasing the redundancy of the bridge, but is found useful to increase the efficiency of the bottom X-type bracing to increase the load carrying capacity and redundancy of bridge.
Adopting the performance based design method would allow us to use hybrid plate girders. Hybrid plate girders consist of low strength materials for web plates, and are considered to have a potential for rational and economical design for steel girders. However, experimental and analytical data on the behavior of hybrid plate girders seem to be insufficient. In this study, a total of 249 hybrid plate girders were analyzed, focusing on moment-shear interaction and shear load-carrying capacity. No clear moment-shear interaction was confirmed as stated by other researchers; and based on analytical results, a modification method on the shear strength equation was proposed.
The ultimate strengths of compressive steel plates simply supported on three sides and one side free (outstanding plates) were numerically investigated by means of combining FE elasto-plastic analysis and Monte Carlo simulation considering the statistical data for variability of the initial displacement and residual stress. From this study, the following results were obtained: (1) a standard deviation of the ultimate strength tends to increase in the region of the with-thickness ratio parameter R ≅ 1.0; (2) in the region of R < 0.7, the effect of the residual stress on the ultimate strength is very small; and (3) considering the statistical data for variability of the initial displacement and residual stress of the plate, a rational design formula can be proposed.
Corrosion damages have been frequently occurrd at end parts of steel girders. So it is frequently used for repair and strengthening works of steel bridges that adding the bracket members, patch plates with epoxy resin. As girder end has narrow space, it is required the simple and rational repair method of the steel girder end with the corrosion damage. In order to make clear load carrying capacity of a steel girder with corrosion damage at the girder end and repaired steel girders, the loading experiments has been carried out. The specimens modelled a steel girder end which are designed with actual size are prepared. It is concluded that the load carrying capacity of the simple and rational repair method is as same as that of the former repair method.
An end cross girder plays an important role when the steel girder bridge is subjected to seismic loading. But located near the girder end, it is often found corroded, which could degrade the load-carrying capacity. Therefore, it is of a practical significance to investigate the seismic performance of a corroded end cross girder. To this end, the present study conducts nonlinear finite element analysis of end cross girders with various corrosions under horizontal load. It is observed that the corrosion area and the plate-thickness loss influence the load-carrying capacity, and their influence depends on the corrosion type. It is also pointed out whether or not the lower flange is connected to the main girder makes a large difference in the load-carrying capacity: the connection between the lower flange and the main girder is therefore very important for seismic performance.
Structural use of stainless steels is attractive, because it is able to contribute to ease of maintenance due to superior corrosion resistance.This paper shows ultimate compressive strength of austenitic stainless steel SUS 304 colomns with welded box cross-section. At first, in order to assess compressive structural response, the modified version of Ramberg-Osgood material model is incorporated into FE analysis program developed by authors. Secondly, parametric studies are carried out to investigate effects of the slenderness parameter, residual stress, and stress-strain curve on the ultimate compressive strength. Finally, the ultimate compressive strength curves of the stainless steel columns are discussed in comparison with design curves specified in several design standards.
Strength of compression members in a steel truss bridge are generally calculated as that of a pin-connected member by considering their effective buckling length. But the strength of the members is to be figured out by considering rotational restriction by gusset plates through FEM analysis of the truss bridge. Then, effects of the gusset plates on the ultimate strength and deformation of the compression members are discussed in this paper. It is concluded that the compression members can be classified into 3 types depending on bending moment distributions and deformation modes at their ultimate state and the ultimate strength of the compressive members in truss bridge can be obtained by those of the single column with different boundary conditions with the member positions.
The concrete capacities of wind turbine pedestals are investigated by using the non-linear FEM analysis. It is found that the type of failure mode of concrete pedestal is due to bending moment. The design formulae are proposed to consider the effects of compressive strength of concrete, embedded depth of the anchor bolt and pedestal size.
Cyclic loading tests on RC bridge column specimens with low reinforcement ratio using deformed bars and round bars respectively were carried out to investigate the horizontal resistance characteristics of old existing RC bridge piers. As results, it was revealed that the specimens with low reinforcement using both round bars and deformed bars showed remarkable locking behavior, finally buckling and fracture of longitudinal reinforcement in the very short range at pier base occurred without plastic hinge forming. These differ form general RC bridge columns.
The purpose of this study is to identify human walking lateral force by using FFT power spectrum from the experimental acceleration data of the human body. An experiment on human walking is carried out on a stationary floor paying attention to higher components of dynamic lateral walking force. It is known that the lateral main component with frequency of fh is applied at half the footfall frequency of fw (fh =0.5×fw). Based on measured lateral acceleration data of the human lumbar, not only main component with frequency of fh, but also higher component with frequency of 2×fh, 3×fh is observed. Characteristics of these higher components of dynamic force by walking are revealed from the dynamic design viewpoint of pedestrian suspension bridges prone to lateral vibration due to the crowd.
Recently, extension of the active use life span of infrastructures has been a big problem in all over the world. In usually, the inspection and judgment of damage level of structures are mostly carried out by expertise professional engineer. Therefore, it is required to establish the useful health monitoring system for the judgment and diagnosis of structural damage level and its position. In this study, the damage identification health monitoring system by using piezoelectric element is produced. The fundamental examinations are performed from the observation of wave motion and Fourier spectrum of the monitoring data. The possibility of effects and application for real structures of the methods in this study is discussed from these results.
This paper reports on the assessment of a bridge state based on the responses of a passing vehicle. Herein to recognize the difference between intact state and damage state, occurrence histogram of dominant frequencies obtained by AR method is focused on. As a damage state, rotational support is fixed and also distributed mass is added on the model beam. Measurement tests are repeated 300 times to obtain enough data set to assess the statistical characteristics of the responses of a passing vehicle. Finally, it is found that deviation and mean values of data set of dominant frequencies of damage states are different from those of intact state with a certain confidence level.
This study is intended to discuss changes in modal parameters of a steel truss bridge due to artificial damage through a field experiment. Modal parameters of the bridge are identified by both frequency domain decomposition (FDD) and multivariate autoregressive (AR) model with stabilization diagram. Modal frequencies decreased due to the artificial damage that results in stress redistribution; such a change can be observed when damage was applied at the non-nodal point of the corresponding mode shape. Mode shapes were distorted due to asymmetric damage; mode shapes in the damaged side were deformed clearly as damage was applied at the non-nodal point. Damping ratio was hard yet to use for damage detection.
This study is intended to evaluate the vibration reduction effects of various factors for the vibration responses of Shinkansen viaducts in both vertical and lateral directions under running high-speed trains. The vibration characteristics of the viaducts are clarified by means of the 3D numerical analysis which is verified through comparing the analytical and experimental results. The dynamic reaction forces at the pier bottoms are obtained for further ground vibration analysis as input excitation forces. The influential factors including train type, track irregularity and damping are adopted as important variables which are beneficial to reduce the train-induced vibration of the viaducts.
In this paper, dynamic stress response of a steel girder bridge subjected to vehicles is investigated, using field measurements and numerical simulations. The objective of this research is to investigate the capability of a FE model in predicting bridge response and extend to study stress responses in local members. Comparisons between the measurement and the simulation results were conducted in the global responses and local stress responses. The global responses are in good agreement. Furthermore, the local stress responses in the simulation are sensitive to the area setting of the contact force from the vehicle. By adjusting the contact area of tiers, the simulation obtains a satisfactory match between the simulated and measured responses within 20% difference for all local stress responses.
During the 2011 off the Pacific coast of Tohoku Earthquake, Nagamachi Viaducts on the Tohoku Shinkansen Line, Sendai City, Miyagi Prefecture, Japan, suffered significant damage. In order to analyze the damage mechanism, it is important to evaluate strong ground motions at the viaduct sites with high accuracy, taking into account site effects. In this study, seismic waveforms along the viaduct were estimated based on the SPGA model considering empirical site amplification and phase effects. Using the actual damage data and detailed distribution of the estimated ground motion, this study conducts the statistical analysis on the relationship between the damage ratio and several indices of the ground motion to construct fragility curves. The estimated ground motions and fragility curves will be useful in the detailed study of the damage mechanism.
The Matsurube Bridge, which is located near the epicenter of the 2008 Iwate-Miyagi Nairiku, Japan, Earthquake (Mj7.2) collapsed due to the failure of the ground behind the abutment. In order to analyze the collapse mechanism, it is very important to evaluate the strong seismic motion at the bridge site with high accuracy. First of all, aftershock observations and microtremor measurements were carried out at the bridge site in this study. Next, site effects at the left and right bank of the bridge were evaluated based on the aftershock records. Finally, seismic waveforms at the Matsurube Bridge during the 2008 Iwate-Miyagi Nairiku Earthquake were estimated based on empirical site amplification and phase effects. The estimated seismic motions will be useful for a rational safety assessment of a bridge.
This paper describes seismic response analysis of the Yokohama-Bay Bridge during the 2011 Great East Japan Earthquake, focusing on pounding behavior between tower and girder. In the first part, analysis of recorded seismic response data shows the unexpected response during the main shock and the largest aftershock: 1) the transverse pounding between girder and tower, 2) changes in natural frequency and damping. Second part describes seismic response analysis considering the pounding effect. The results of this numerical analysis reproduce the observed response and show that nonlinear response was caused by the pounding. Finally, we analyzed effect of more severe earthquake excitation. The result of inland level 2 earthquakes indicates the pounding between tower and girder causes the damage of wind shoe.
After the 2011 off the Pacific coast of Tohoku Earthquake, contents for seismic assessment to transmission towers far exceed the assumption of past investigation. Limit state evaluation is required for the seismic assessment of transmission towers to Level 2 earthquake motion, and the importance of damping constant increases in evaluating seismic performance. The purpose of this paper is to investigate the equivalent damping constant used for seismic performance evaluation of transmission towers during Level 2 earthquake considering bolt slip. Furthermore, better arrangement of bolt slip characteristics to use bolt joint positively as kinetic-energy absorbing device is examined.
Shake table tests of large model in 1g gravitational field were conducted to estimate deformation characteristic of asphalt pavement and change of bearing capacity of foundation caused by liquefaction during and after earthquake. FWD used for the maintenance management and damage survey after earthquake of actual airport pavement to confirm of bearing capacity was used for these shake table tests. As a result, subsidence of asphalt pavement became large with rise grade of excess pore water pressure. And FWD deflection of about 1 hour after became smaller than that before shaking, and the result which the bearing capacity of the foundation increases was obtained.
From the impact of tsunami due to the Great East Japan Earthquake, Kesen Bridge locating in the Rikuzentakata of Iwate Prefecture was flowed out. Based on the recording data of videos and photographs, shape and features of tsunami acting on the bridge girder are analyzed. As a result, the tsunami acting on the bridges across Kesen River rose in relatively slow pace with the shape similar to steady flow. In addition, numerical simulation was conducted and the validity was confirmed comparing with the video analysis. According to the overall evaluations, the flowing mechanism of Kesen Bridge was figured out to be flowed by steady flow in horizontal direction with the velocity of about 6m/s.
Many bridges were washed away by the tsunami due to Great East Japan Earthquake. The authors firstly summarized that the tsunami in Tohoku Region mainly showed a steady flow shape, from the video and the photo recording the tsunami along Kesen River. Besides, 1~2m small waves were found at the surge front and the water surface of the steady flow. Afterwards, the experiments simulating bore wave and steady flow were conducted to study the characteristics of the wave shape and the wave forces on the girder model. As a result, with the same wave height, the wave force of the broken bore wave was larger than that of the un-broken bore wave and with similar inundation depths, the wave force of the broken bore wave (prototype: inundation depth 20m, static water 7.5m, wave height 12.5m) is much greater than that of the steady flow (prototype: inundation depth 17.5m).
On March 11, 2011, the huge tsunami caused by the great east Japan earthquake devastated the Pacific coast of north-eastern Japan. Many infrastructures including bridges were collapsed by the tsunami. New generation of tsunami disaster prevention and mitigation method should be reconsidered toward the next millennium Tsunami. In this study, a new boundary treatment using a virtual marker and the fixed boundary particle is developed to control the slip and no-slip boundary condition for the velocity field and to satisfy the pressure Neumann condition at the same time. Finally, the accuracy and efficiencies of our proposed method are validated by comparison between a numerical solution and experimental results.
Many old steel railway bridges with pivot bearings had been used at important parts of the metropolitan transportation network. We had evaluated their basic characteristic on seismic behavior. However, there are various structural types, for example, with unbalanced span ratio, sharp skew, or brace members between the pillar form piers. In this study, we discuss the effect of these various structural types on seismic behavior by cyclic load test of the pivot bearing and seismic response analyses for full structures. In addition, we propose the estimated formula of maximum seismic response for pivot bearings.
It was found that a few retrofitted bridges were damaged during the 2011 Great East Japan Earthquake. Vertical cracks of nearly 10mm width were observed at the shoulder of cap beam in hammerhead RC bridge column with retrofitted body by reinforced concrete jacketing for strengthening the cut-off section of longitudinal rebars during the earthquake. In this study, the strength of several sections in the bridge column were compared to examine the damage mode. Furthermore time history response analyses utilizing the earthquake record observed near the site were conducted so as to reveal damage mechanism of cap beam during the earthquake. Analytical results indicates that the section of the cap beam shoulder in the outbound column is assessed to be the first failure section regardless the effect of the seismic retrofit, which coincides with actual behavior of the columns observed after the earthquake.
It is common in the current steel arch bridges that the weight of the RC deck occupies more than half of the full weight of upper bridge structures. Therefore, the current steel arch bridges are one of the top heavy structures, and then, the large inertial forces act to the RC deck during an earthquake. In consequence, the arch rib base and an end support, etc. are damaged greatly in many cases if seismic design is insufficient. In this paper, as a seismic improvement of the steel arch bridges, the effect of the weight of the deck by exchanging the current RC deck for the lighter aluminum deck onto the improvement of inelastic behavior of the steel arch bridges is numerically investigated. It is found that the steel arch bridges with the aluminum deck are one of the effective seismic improvements.
New seismic dampers named Buckling-Restrained Rippled Plate (BRRP) dampers have been developed. BRRP is similar in shape to BRB (Buckling-Restrained Brace), but its core member is a 2D rippled plate instead of a 1D narrow flat plate. BRRPs are intended to be used as stoppers, setting at the edges of a girder-type bridge, which will act as stiff elastic bearings for Level 1 earthquakes, while for Level 2 earthquakes as energy dissipating seismic dampers. The target performance of BRRPs is such that they can withstand the earthquakes exceeding Level 2 earthquakes (say, 1.5 times larger than Level 2 earthquakes). The elasto-plastic behavior of BRRPs has been investigated using cyclic loading tests and analyses to acquire the fundamental knowledge of their performances.
It's important to determine an appropriate ratio of horizontal force shared by dampers and piers when a vibration controlled bridge is designed by using hysteretic dampers. However, there is no guideline to show how to make an effective decision on the dampers. In this paper, a trial was made to propose an approach for design practice based on analytical study. A SDOF system model was used for nonlinear analysis on various conditions of piers. Among the analytical results, the hysteretic energy absorbed by dampers and the maximum response displacements were focused, with which the appropriate damping force was suggested. Further, an approach to decide the damping force is proposed, which should be helpful for engineering practice.
The bridge restrainers are expected to prevent unseating of bridge deck and also to resist the seismic impact force. However, standard evaluation and design method for the shock absorbers are not yet established. In the meantime, a pin fixed cable type restrainers are newly developed. The pin fixed assembly allows the cable to rotate, creating no restriction to their brackets' mounting angle. The purpose of this research is to understand the shock absorbing capacity of the new restrainers with rubbers around the pins. First, seismic force acting on the restrainer is estimated by the FE analyses on the bridge model, and then impact load tests are conducted to quantitatively evaluate the shock absorbing capacity of three different sizes of the bracket models of the new type cable restrainers.
Super high damping rubber (HDR-S) isolators show about 20 % higher damping characteristics than conventional high damping rubber (HDR) isolators. The characteristics of HDR-S isolators depends on the shear strain, temperature, and loading cycles. Especially the characteristics between the virgin loading and the sebsequent loading are drastically different. The objective of this study is to pursue realistic dynamic response of HDR-S isolators in the virgin loading state based on the results of the pseudodynamic tests.
The objective of the study is to develop a simple measurement method of the wind-induced response of wind turbine blades under its operation. A 3 dimensional motion analysis software was used. In order to obtain the blade tip vibration data, two hi-speed cameras had to be set so that they conform to the similarity between the measurement and the calibration, and image processing was helpful to have more stable tracing results. An accurate coordinate transformation was also necessary. The obtained response in along-wind direction sometimes had error caused by miss-tracing of the blade tip, and may not be accurate enough. But the obtained response frequency seemed to correspond to the natural frequency of the blades.
This paper presents an investigation into the effect of flap on wind flow across a box girder section by a numerical study. The Reynolds Average Navier-Stokes (RANS) approach coupled with a new k-ε eddy viscosity turbulent model is utilized in study. Firstly, a comparison between the obtained results in numerical analysis and the ones in wind tunnel test is mentioned. Then, an investigation into the wind flow mechanism around the section, in the presence of flap(s) with various geometrical configurations, is conducted to clarify the significance of flap(s) in vortex-induced vibration suppression. Finally, how flap(s) disturbs the wind speed profile above the section is considered as a side effect to vehicles. The purpose of this paper is to provide useful reference for flap application to a box girder when vortex-induced oscillation occurs.
As one of the anti-galloping devices, interphase spacers have spread widely. However, effective arrangements of interphase spacers against galloping of snow accreted transmission lines are not examined enough until now. In this paper, in order to clarify the effective arrangements, the numerical simulations of galloping under acting artificial wind are repeated to many arrangements which can be considered, and the response statistics are evaluated. Using the statistical multiple comparison procedures, the optimal arrangement is determined considering the variation in the galloping response. Moreover, the difference in natural mode of transmission line by the arrangements is clarified, and the reason for the optimal arrangement is analyzed based on natural mode.
In this paper, computational fluid dynamics for flow around a circular cylinder is carried out by means of solving the incompressible Navier-Stokes equations with the turbulence model by the finite element method. The Reynolds number is from Re=2.0×105∼4.5×105. By using results of calculations, the flow patterns, drag, lift and pressure coefficients and Strouhal number depend on the Reynolds number are investigated. There are differences between the computational data and the experimental data, however the dependence of the Reynolds number and the drag crisis in the Critical Reynolds Number regime can be simulated near wake.
Spatial correlations of fluctuating lift forces on 2-dimensional rectangular sections with various side ratios in smooth flow are evaluated by wind tunnel tests and LES analyses. The effect of unsteady reattachment of separating shear layer on spatial correlations is investigated in this research. The results of wind tunnel tests reveal that the unsteady reattachment strengthens the spatial correlation. The difference of shear layer movement between completely separating flow type and unsteady reattaching flow type is clarified by LES analyses. The shear forces between two separating shear layers caused by phase difference of Karman vortex in reattaching flow leads to high correlation.
The complex cable aerodynamics has being studied by many researchers. The traditional vibration of stay cable caused by rain-wind combination has been known as most typical type and many kind of countermeasures has been proposed for suppressing this kind of vibration. Recently, stay cables were proved that they could be vibrated not only in rain-wind condition but also in dry state. Some of authors have pointed out the significant role of an axial flow in a wake of inclined/yawed cable for galloping instability. In this study, dry-state galloping was investigated by a wind tunnel test with various kinds of relative wind angles and three types of counter- measures have been proposed to suppress dry-state galloping of stay cable.
For solar panels, it is vital to ensure adequate wind-resistance performance. JIS has provided an approximation formula for calculating the wind force coefficient, which must be understood to ensure wind performance. In addition, when a mega-solar system is installed, it is well known that for solar cells located at the center, half the value of the wind force coefficient as compared to that of the surrounding solar cells subject to direct wind exposure may be applied. However, the zone of solar panels for which half the wind force coefficient may be applied has not been clearly identified. Given the situation, we approached the development of a design methodology for reductions in solar panel framework cost and foundation construction cost.
This paper presents the aerodynamic force behavior on a photovoltaic panel due to ground effect. The aerodynamic force coefficients of a two-dimensional flat plate model that was installed near the ground plate were measured in a wind tunnel. The test parameters were the clearance height from the ground plate and the angle of attack of the model. The trends of the ground effect depend on not only the wind direction (upwind or downwind) but also the angle of attack. The rates of change in the drag and lift forces caused by the ground effect are similar. However, the rates of change in the moment are different from that in the drag and lift forces. The difference can be described by the flow pattern around the model as estimated by the center of air pressure.
Numerical simulations are performed to evaluate the ground effect of ground-mounted photovoltaic panel. The simulation results agree well with the wind tunnel experiments in aerodynamic force characteristics. The visualized simulation results showed that the blockage effect increases the pressure under the panel, and the separation vortex at the leading and trailing edge decrease the pressure on the panel. The flow pattern changes as the panel approaches the ground. The change of the flow pattern suggests that the blockage effect and the behavior of the separation vortex at the trailing edge influence well on the ground effect.
Simplified bridge health indices for RC deck, RC beam, PC beam and steel beam are proposed that take into account the deterioration mechanisms based on the statistical analysis of the bridge inspection data for 1200 bridges between 2001 and 2006 by Gifu prefecture. The inspection data were statistically analyzed by the principle components analysis and the cluster analysis, where the results are interpreted carefully by referring to the pictures taken at the time of the inspection to identify the deterioration mechanisms. Furthermore, the changes of the design codes and the construction details are considered in interpreting the results. One of the distinguished characteristics of the proposed health indices for each part is that they consist of 2 indices: the first one measures the general deterioration of each part, whereas the second one indicates the responsible deterioration mechanism.
In this paper, we report on the development of estimation system for IRI (International Roughness Index) using motor bicycle. Herein the characteristics of five kinds of motor bicycles are examined using hamp calibration test based on their impulse response. Finally IRI estimation was conducted by the sprung and unsprung masses of quarter car models corresponding to the front and rear halves. As a result it is found that the reposens of front sprung mass can be used for IRI estimation.
This paper shows a basic study for the health monitoring of the bridge bearing that is one of important structural components of the bridge. A Brillouin-scattering based fiber-optic sensor; PPP-BOTDA, was adopted to assess the strain distribution changes of girders due to uncertain changes of the bridge bearing performance; i.e., boundary condition changes. An experimental verification was carried out using a simply-supported beam structure with the bearings that could change the performance of their slide and rotation mechanisms. We then proposed an index to extract the change of strain distribution profile due to the change of bearing performance with considering the measurement noise. It was additionary shown that the index was able to indicate the gradual changes of bridge bearing performance quantitatively from the result of an analytical verification.
Recently, deterioration of infrastructures has become obvious as social problem, and application of structural health monitoring to maintenance attracts attention increasingly. However, method to evaluate the relation between local damage and data measured by monitoring has not been investigated enough. Then, damage detection method focusing on the spatial deformation has been proposed and is investigated by numerical simulation continuously. In this paper, damage evaluation of RC beam is conducted in combination of experimental and analytical approach. In experiment, latest optical distributed strain measurement system is applied. And damage detection method using wavelet decomposition is also proposed and evaluated.
This paper demonstrates the changes of natural frequencies and modes of a PC bridge with a skew angle of 30 degrees throughout all the construction stages from production of a PC box-beam at factory to completion of asphalt pavement work by using a portable vibration measurement system with hammering excitation. This paper clarifies as follows: The first mode of vibration and first predominant frequencies of 14 individual PC beams are closed to the first natural frequency and mode of a simply supported beam. The bridge behaves as a plate after shear key development followed by transverse post-tensioning for integration of single beams. We experimentally confirmed that its first natural mode is longitudinally bending and its second mode is torsional. The largest increase of the first natural frequency occurred after integration, however remarkable decrease observed after asphalt pavement.
The paper presents the monitoring of bridge response based on dynamic vibration tests of a skewed bridge using a moving vehicle and its verification by numerical simulation. The plural major natural frequencies of a skewed bridge in the narrow frequency band can be verified by the smoothed power spectra of the measured acceleration responses. Because of the good correlation of the natural frequency between measurements and simulation results, the better understanding of the dynamic characteristic of the skewed bridge can be obtained. Due to the parametric studies, the effect of the traffic lane of the moving vehicle, the roughness of the road surface and the deterioration of the superstructure elements can be verified.