• Smart Structures and Systems
• /
• v.32 no.5
• /
• pp.297-308
• /
• 2023

Dynamic deflection is important for evaluating the performance of a long-span cable-stayed bridge, and its continuous measurement is still cumbersome. This study proposes a dynamic deflection monitoring method for cable-stayed bridge based on Bi-directional Long Short-term Memory (BiLSTM) neural network taking advantages of the characteristics of spatial variation of cable acceleration response (CAR) and main girder deflection response (MGDR). Firstly, the relationship between the spatial and temporal variation of the CAR and the MGDR is described based on the geometric deformation of the bridge. Then a data-driven relational model based on BiLSTM neural network is established using CAR and MGDR data, and it is further used to monitor the MGDR via measuring the CAR. Finally, numerical simulations and field test are conducted to verify the proposed method. The root mean squared error (RMSE) of the numerical simulations are less than 4 while the RMSE of the field test is 1.5782, which indicate that it provides a cost-effective and convenient method for real-time deflection monitoring of cable-stayed bridges.

• International Journal of Ocean System Engineering
• /
• v.2 no.3
• /
• pp.195-199
• /
• 2012

This paper reports a new analytical method to calculate the planar displacement of structures. The cross-sections were assumed to remain in plane and the deflection curve was evaluated using the curvature values geometrically, despite being solved with differential equations. The deflection curve was parameterized with the arc-length of the curvature values, and was taken as an assembly of chains of circular arcs. Fast and accurate solutions of complex deflections can be obtained easily. This paper includes a comparison of the nonlinear displacements of an elastic tapered cantilever beam with a uniform moment distribution among the proposed analytical method, numerical method of the theory and large deflection FEM solutions.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1444-1451
• /
• 2010

This paper aims for proposed the deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration when a train passes a railway bridge. For this purpose, bridge-train transfer function was derived and bridge-train interaction analysis was performed by using the derived function. The vertical acceleration signals of passenger cars obtained from bridge-train interaction analysis were compared with them from the bridge-train transfer function by moving constant force analysis. Therefore it was estimated possible to induce the comfort deflection limit of railway bridge by using bridge-train transfer function. The deflections by moving force of single span bridge and continuous bridge were assumed as sine and haversine wave. The deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration can be expanded using bridge-train transfer function and bridge comfort limit considering serviceability due to bridge vibration. And it was compared to other allowable deflection limits of railway bridge design specifications.

• Steel and Composite Structures
• /
• v.26 no.1
• /
• pp.45-53
• /
• 2018

Experimental investigations have revealed significant mismatches between analytical estimates and experimentally measured deflections of transmission towers. These are attributed to bolt slip and joint flexibility. This study focuses on effects of joint flexibility on tower deflections and proposes criterions for permissible deflection limits based on the stresses in joints. The objective has been framed given that guidelines are not available in the codes of practices for transmission towers with regard to the permissible limits of deflection. The analysis procedure is geometric and material nonlinear with consideration of joint flexibility in the form of extension or contraction of the cover plates. The deflections due to bolt slip are included in the study by scaling up the deflections obtained from analysis by a factor. Using the results of the analysis, deflection limits for the towers are proposed by limiting the stresses in the joints. The obtained limits are then applied to a new full scale tower to demonstrate the application of the current study.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.5
• /
• pp.73-80
• /
• 2002

In this study, work materials of the ree form surface shape was machined by ball end mill cutter according to the change of cutting location and depth, and the acquired data of cutting force, tool deflection and shape accuracy were analyzed. Cutting force results were obtained with tool dynamometer and tool deflection values were measured by a couple of eddy-current sensors. Shape accuracy was obtained by roundness tester and surface profile measuring machine. As inclination angle was decreased, cutting force was increased. Cutting force showed large value at $105^{\circ}$ and $150^{\circ}$. Tool deflection was less at down milling than at up milling, decreased at 45$^{\circ}$ and 120$^{\circ}$, and shown large tool deflection at $150^{\circ}$. Roughness values were found to be bad in the inside of surface shape tool deflection. Surface accuracy was obtained better precision in down milling than in up milling.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.820-823
• /
• 2000

The characteristics of wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of tungsten carbide in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension, the gap of deflection was decreased after thickness 60mm and discharge time of 6$\mu\textrm{s}$ due to the changing from fundamental mode to vibration mode. The deflection is the smallest at the water specific resistivity of 7.5 kΩ ㆍcm. The deflection is found to be decreased as increasing dwell time, and the result is due to the vibration of the pressure and the amount of the dielectric. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, was observed for rough wire-cutting EDM of STD-11. This phenomena is found to be decreased as the number of EDM is increased. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• Computers and Concrete
• /
• v.30 no.6
• /
• pp.445-453
• /
• 2022

A pre-cambered deep deck-plate system has been developed that can realize a long span by offsetting the deflection caused by a construction load. In this study, finite element (FE) analysis is performed to examine the preload-camber relationship introduced into a deck and calculate the deflection reflecting the ponding effect that arises during concrete pouring. The FE analysis results showed that the stress of the bottom plate was half of the yield stress when the pre-camber of approximately 30 mm was introduced. Based on the FE results, a full-scale deep deck-plate is fabricated, a pre-camber is introduced, and concrete is poured to measure deflection. A deflection calculation formula that reflects the ponding effect is proposed, and the deflections yielded by the proposed model, experimental results, and FE results are compared. Results show that the proposed model can accurately estimate the deflection of non-supported deep deck-plate systems after concrete is poured.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.66-71
• /
• 2004

Estimation of the CANDU pressure tube deflection is important since the deflection may cause significant structural failure due to hydrogen diffusion and blister. However, there is no appropriate engineering model to estimate it exactly. The purpose of this paper is to propose a new analysis method and program to resolve this issue. For development of proper analysis method, a series of finite element analyses has been carried under elastic-creep condition. In addition, for effective estimation of the creep deflection, an analysis program named PC-DAS was developed based on the proposed method. Comparison of simple case study results with corresponding reference ones showed good agreement. Therefore, the proposed method and program can be utilized as one of valuable toolkit for integrity assessment of CANDU pressure tube.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.37-40
• /
• 2006

In this paper, long term deflection of RC beam with variable substitution ratio of recycled aggregate is investigated. 6 RC beam specimens are designed using concrete made of coarse aggregate of 25mm size, mix strength of 21MPa, slump of 12cm and air content of $5.0{\pm}1.5%$. A few concrete blocks are made and used for long term loading. The loading and deflection instrumentation are conducted following the process codified in ACI 318-05 code. Test result shows that the deflection of specimens depends on the compressive strength of concrete. And it is concluded that the deflection of RC beam can be predicted like normal beam using ACI formula if certain level of compressive strength is acquired even recycled aggregate is used in making the beam.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.372-375
• /
• 2003

MCA deflection control is a important technology for the development of MEMS applications. In this study, deflection analysis at the MLA/Si diaphragm was investigated by Finite Element Method. Analysis of Si diaphragm combined with MCA has been implemented into the ANSYS (Solid5 and Solid45). On the basis of this structure, deflection versus MCA number of layers has been modelled and MCA/Si contact area characteristics with different diaphragm conditions were analyzed. Consequently, it is expected that fabrication technology of MCA/Si diaphragm could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.