Monorail Bridge Research Articles

Intelligent path planning for civil infrastructure inspection with multi-rotor aerial vehicles

This paper presents the development of algorithms for high-level control and intelligent path planning of multi-rotor aerial vehicles (MAVs) in the tasks of inspecting civil infrastructure. After revisiting the multicopter modeling, we describe the hierarchy of high-level control for MAVs and develop optimization algorithms for generating optimal paths and enabling automatic flight during inspection tasks, making use of the digital twin technology. A co-simulation framework is then established to simulate and evaluate inspection mission scenarios, integrating these essential components. Real-world examples from built infrastructure illustrate this concept. An advantage of this approach is its ability to rigorously test, validate, verify, and evaluate MAV operations under abnormal conditions without requiring physical implementation or field tests. This significantly reduces testing efforts throughout the development cycle, ensuring optimal cooperation, safety, smoothness, fault tolerance, and energy efficiency. The methodology is validated through simulations and real-world inspection of a monorail bridge.

Monorail bridge inspection using digitally-twinned UAVs

This paper introduces a comprehensive approach to monorail bridge inspection utilizing unmanned aerial vehicles (UAVs) and digital twin technology. The autonomous UAV-based inspection design encompasses UAV dynamics, tracking control, path planning, and task execution. A dedicated digital twin platform is developed to facilitate rigorous testing and verification of UAV control, mitigating the necessity for extensive physical testing. Methodology validation is achieved through a combination of simulations and real-world experiments, affirming its efficacy in authentic scenarios and demonstrating the potential for advancing infrastructure inspection practices.

Minimising the embodied carbon of reinforced concrete piles using a multi-level modelling tool with a case study

The construction industry is one of the main contributors to the increasing carbon emissions globally. With an increasing interest in optimising the embodied carbon of superstructures, very little attention is paid to optimising the embodied carbon of substructures although foundations are responsible for a considerable share of the total carbon emissions within any structures. This research focuses on minimising the embodied carbon of reinforced concrete piles and introduces a novel multi-level modelling tool that can be used by designers to discover the full range of feasible design scenarios with optimised environmental impact. Results show that adjusting design parameters like concrete grade (fck), pile slenderness ratio (L/D) and steel-to-concrete ratio (As/Ac) can lead to a significant cut in the final value of embodied carbon. The modelling tool is applied to a case study of a monorail bridge and showed that a 51.4% potential carbon saving can be achieved through adjusting the design parameters, moreover, a significant 72.4% cut is achievable if this is coupled with switching to cleaner materials.

Dynamic Analysis of Suspension-Type Monorail Long-Span Cable-Stayed Bridge in a Wind-Vehicle-Bridge System

The suspension-type monorail (STM) is a new type of rail transit, currently developing rapidly in China. Due to its short construction duration and high terrain adaptability, STM can save large land resources. In particular, by supplementing the traffic systems in large and medium-sized cities, STM can contribute to green tourism projects. However, no systematic study is devoted to the STM transit system in China, and there is still a lack of relevant knowledge and exploration, especially for the special combination system monorail bridge. In view of the real STM bridge, namely a long-span (55 + 100 + 55)-m cable-stayed bridge in this paper, and by applying wind-vehicle-bridge coupling vibration theory, ANSYS finite element method software, and Universal Mechanism multi-body dynamics software, finite element models are established for the bridge and multi-body vehicle, respectively. Furthermore, a co-simulation method is adopted to analyze vehicle-bridge coupling vibrations and ride comfort quality. According to the results, the dynamic responses of the monorail bridge and vehicle are greatly affected by the variation in wind speed, and it is necessary to take measures to decrease system vibrations, thereby ensuring ride comfort quality for vehicle passengers.

Seismic analysis of soil-pile-bridge-train interaction for isolated monorail and railway bridges under coupled lateral-vertical ground motions

Most of the common monorail bridges in the world are non-isolated ones due to their low superstructure weight. Recently, a limited study on the innovative isolated monorail bridges demonstrated that seismic isolation systems can be beneficial to monorail bridges. In this study, a parametric analysis of soil-pile-bridge-train (SPBT) interaction during frequent earthquakes was performed to better understand the seismic behavior of the novel isolated monorail bridges compared to the traditional non-isolated monorail bridges and the conventional railway bridges. To evaluate the influence of train-bridge interaction (TBI) on the seismic response of bridges under the combined vertical and horizontal ground motions, Taiwan Railway Bridge (TRB), and Qom Monorail Bridge (QMB) with and without isolators were selected. A total of 2268 time history analyses, including different isolator shear modulus, train locations in two vehicle modeling approaches, pier heights, and ground motions in different directions, were performed using the substructuring method. The results were verified by comparing the 3D continuum finite elements. The observations indicated that when lateral and vertical excitations were applied simultaneously, for monorail bridges where the trains’ weight usually reached up to 50% of the weight of a couple of the guideway beams, the presence of the train led to creating the critical conditions. However, for the conventional railway bridges with relatively low train-to-deck weight ratios (less than 30%) ignoring the train could cause the most critical responses in the SPBT system, regardless of the vehicle modeling approach. It was also found that the efficiency of seismic isolation systems for conventional railway bridges is higher than that for monorail bridges.

Experimental study of the load-deformation behaviour of the precast post-tensioned continuous girder for straddle monorail: Full-scale load test under service and ultimate loading conditions

This study presented the results of an experimental program conducted on a newly proposed Full-scale Precast Post-tensioned Continuous (FPPC) girder for straddle monorail. The investigated FPPC girder represents the actual size, design and construction details for a newly designed monorail transit system (Yellow Line and Pink Line Monorail) in Bangkok, Thailand. The salient features of the newly proposed girder system include lightweight, low-cost, easy and fast construction. The newly proposed FPPC girder is mainly comprised of three reinforced concrete (RC) hollow haunched girders, four piers or supports, two pier segments, four wet joints, and four bearings at each support. The FPPC girder was constructed at the casting yard of Sino-Thai Engineering and Construction Public Company Limited (STECON), Thailand. The FPPC girder was tested under different loading conditions (such as service and ultimate loading conditions). Both service and ultimate loads were applied as two-point loadings. Service load in a monotonic manner was applied on the right exterior span (two-point), middle span (two-point), and on the left exterior span and middle span (four-point). Meanwhile, the ultimate load in a monotonic manner was applied only on the left exterior and middle span as a four-point loading scheme. The test results indicate that the behaviour of the FPPC girder under service load conditions is elastic. Further, cracking of the concrete was not observed at any location. The observed maximum deflections under service load conditions were less than the permissible limits at all locations. Further, the maximum ultimate load-carrying capacity was observed to be much greater than the design load under ultimate loading conditions. This is an indication that the design details and construction procedure of FPPC girder are appropriate and further that this system could be used effectively to construct straddle monorail transit systems. Finite element analysis of FPPC monorail bridge girder was also performed by using a computer program ATENA which is a computational tool for nonlinear engineering analysis of bridges and culverts. The finite element analysis results indicate that the computer program ATENA is well capable to predict the ultimate load carrying capacity, displacement and cracking patterns of FPPC girder.

Hierarchical Convolutional Neural Network With Feature Preservation and Autotuned Thresholding for Crack Detection

Drone imagery is increasingly used in automated inspection for infrastructure surface defects, especially in hazardous or unreachable environments. In machine vision, the key to crack detection rests with robust and accurate algorithms for image processing. To this end, this paper proposes a deep learning approach using hierarchical convolutional neural networks with feature preservation (HCNNFP) and an intercontrast iterative thresholding algorithm for image binarization. First, a set of branch networks is proposed, wherein the output of previous convolutional blocks is half-sizedly concatenated to the current ones to reduce the obscuration in the down-sampling stage taking into account the overall information loss. Next, to extract the feature map generated from the enhanced HCNN, a binary contrast-based autotuned thresholding (CBAT) approach is developed at the post-processing step, where patterns of interest are clustered within the probability map of the identified features. The proposed technique is then applied to identify surface cracks on the surface of roads, bridges or pavements. An extensive comparison with existing techniques is conducted on various datasets and subject to a number of evaluation criteria including the average F-measure ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$AF_\beta $ </tex-math></inline-formula> ) introduced here for dynamic quantification of the performance. Experiments on crack images, including those captured by unmanned aerial vehicles inspecting a monorail bridge. The proposed technique outperforms the existing methods on various tested datasets especially for GAPs dataset with an increase of about 1.4% in terms of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$AF_\beta $ </tex-math></inline-formula> while the mean percentage error drops by 2.2%. Such performance demonstrates the merits of the proposed HCNNFP architecture for surface defect inspection.

Influence of bridge parameters on monorail vehicle–bridge system— A research with multi-rigid body and multi-flexible body coupling theory and Park method

The parameters of the monorail bridge, which have a significant effect on the vehicle, are analyzed in this paper. With Park method, a complicated solver of the second order with a variable step size, equations insolvable to traditional methods can be solved and a more complicated dynamic model could be built. Different from some traditional simulation of vehicle–bridge coupling system, the bridge is divided into the girder and piers. The finite element model of each part is created separately in Ansys and coupled with the vehicle system in UM, which helps the analysis of the interaction forces between flexible components and better simulation accuracy can be obtained. FIALA model is used to calculate the wheel force. These methods make the measurement more precise. The study shows that all the variables except for the stiffener thickness have little effect on the vibration of the vehicle due to the good vibration reduction performance of the vehicle system. The resonance of the girder could be avoided by changing the thickness of the stiffeners and web plates. In addition, high stiffness and damping of the connection point of the girder and pier are helpful in alleviating the vibration of the bridge.

Seismic Retrofit of Monorail Bridges Considering Soil–Pile–Bridge–Train Interaction

Abstract Monorail bridges play an important role in urban transportation networks, and their proper seismic performance is an issue of great concern in earthquake-prone countries. Seismic isolation...

Nonlinear dynamic analysis of Qom Monorail Bridge considering Soil-Pile-Bridge-Train Interaction

Railway tracks experience has shown that considering the effects of Soil-Structure Interaction (SSI) especially for soft soil sites is necessary. These effects can also be important for monorail bridges on soft soil beds. The main aim of this study is to investigate the effects of Soil-Pile-Bridge-Train Interaction (SPBTI) on the Qom Monorail Bridge (QMB) responses. In spite of many studies on the effects of monorail train-bridge (fixed-base structure) interaction, very little information is available in the literature on the effects of monorail trains on SPB systems. In this paper, an advanced three-dimensional (3D) continuum finite element analysis of QMB subjected to train moving loads was developed. The SPBT models have been validated using three case studies (two bridge-monorail train studies and a soil-pile-structure study) available in the literature. The maximum displacements of the guideway beam at the different train speeds were obtained for various SPBT system conditions. The effects of the stiffness and thickness of the soil, the bridge span length, and the amplitude, length, and geometry of the train loading on the critical speed of the SPBT system are discussed in detail. Finally, the results have been synthesized into simple design charts to select the appropriate straddle-type monorail train and determine its critical speed for a particular soil-bridge condition. In addition, a new simple method for simulating the behavior of the finger-bands (as one of the excitation source of vertical bridge vibrations) in commercial software was presented. The results show that the position of a monorail train bogies plays an important role in determining critical speed so that with uniformity the spacing between the bogies decreases the critical speed in the vertical direction.

Dynamic Response Analysis of the Straddle-Type Monorail Bridge\u2013Vehicle Coupling System

An analytical procedure of dynamic interaction analysis of the straddle monorail bridge–vehicle coupling system is proposed in this paper based on the finite element method and energy method. The calculation procedure is programmed with VB language for the solution of the governing motion equations of the straddle-type monorail bridge–vehicle coupling system. The effects of speed, three kinds of loads and different radius of curvature on dynamic responses of the monorail bridge–vehicle coupling system are analyzed. The simulation indicates that vertical vibration amplitude of the track beam decreases while the lateral amplitude increases with the increase in the radius of the curvature; the maximum value in lateral and vertical direction is 0.075 and 0.43 mm, respectively; and the maximum amplitude (lateral and vertical) and acceleration (lateral and vertical) are 0.69, 0.046 mm, 0.15 and 0.62 m/s2, respectively, at the speed of 80 km/h. The vibration amplitude (lateral and vertical) and vertical acceleration increase with the increasing load, and the maximum values are 0.041, 0.43 mm and 0.44 m/s2, respectively. The lateral acceleration is not easily affected by the load conditions.

Successful launch of 450MT girder for monorail bridge at Currey Road, Mumbai

Recently in September 2015, Mumbai Metropolitan Region Development Authority (MMRDA) successfully executed a Herculean task of its project 'Mumbai Monorail'. This involved launching (erection) of 450 metric ton girder bridge above the railway tracks for the monorail in a short span of few hours. Present study analyses painstaking efforts of the project team on the sidelines of project management framework.

Successful launch of 450MT girder for monorail bridge at Currey Road, Mumbai

Successful launch of 450MT girder for monorail bridge at Currey Road, Mumbai

Dynamics of the Monorail Train Subjected to the Braking on a Straight Guideway Bridge

Abstract A finite element (FE) model of the straight guideway bridge under monorail train has been built in this research in order to investigate dynamic interactions of the coupled system in the vertical and longitudinal direction. A limited length of the straddle monorail bridge including five continuous spans is modeled in three dimensions by using FE method. A 3D model of the monorail train system, built in the multibody analyzer MSC ADAMS, is assembled over the bridge. The entire model, consisting of the vehicle and bridge subsystems, is numerically analyzed by performing dynamic simulation in time domain. The braking forces between the train tires and guideway beams are activated in the analysis, in addition to the dead weights of the components and the train live loads. Dynamic forces in the tires are obtained for the case of the emergency braking in the system. The reaction forces, appeared in the bridge piers, are reported as the input forces for the purpose of the bridge design.

Dynamic interaction of the monorail–bridge system using a combined finite element multibody-based model

To assess the dynamic behavior of monorail–bridge system, an innovative model of train–guideway interaction has been developed based on multibody dynamics and finite element simulation. A finite element model of guideway structure for a particular monorail system is built up using parametric design language, considering a specific length of straddle monorail line in three dimensions. Both straight and curved track geometries are modeled to simulate the actual bridge infrastructure. Flexible elements are adopted for the guideway beams consisting of reinforced concrete profiles to increase the accuracy of the numerical simulations in a more realistic way. The bridge model indeed, is simulated using a beam-frame structure of composite steel–concrete material. A multibody simulation of monorail vehicle is then introduced using the commercial multibody software MSC Adams. The three-dimensional multibody model of the monorail vehicle together with the bridge subassemblies is eventually implemented in multibody environment. The entire dynamic model of the vehicle-track system consists of all flexible and rigid body elements. Dynamic responses of the vehicle and bridge system are then extracted for different loading conditions. The proposed numerical model is validated using some dynamic simulation results of the system from the vehicle manufacturer in the selected case study. The model is further verified against several analytical and measurement results reported in the literature both for straight and curved track configurations. The result of dynamic simulations gives an overview about the dynamic forces and reactions that can appear in bridge structure due to the train movement.

SEISMIC BEHAVIOR OF STEEL MONORAIL BRIDGES UNDER TRAIN LOAD DURING STRONG EARTHQUAKES

This paper investigated dynamic responses of steel monorail bridges incorporating train-bridge interaction under strong earthquakes. Two types of steel monorail bridges were considered in the study: a conventional type with steel track-girder; an advanced type with composite track-girder and simplified lateral bracing system. During strong earthquakes, monorail train was assumed standing on the track-girder of monorail bridges. Observations through the analytical study showed that considering the monorail train as additional mass rather than a dynamic system in numerical modeling overestimated effect of the train load on seismic performance of monorail bridges. Earlier plastic deformations at the end bracing of the girder system absorbed seismic energy and reduced the stress at the pier base.

Substructure method in high-speed monorail dynamic problems

Substructure method in high-speed monorail dynamic problems

Seismic response of a monorail bridge incorporating train-bridge interaction

Dynamic responses of the bridge for a straddle-type monorail subjected to the ground motion of high probability to occur are investigated by means of a three-dimensional traffic-induced vibration analysis to clarify the effect of a train's dynamic system on seismic responses of a monorail bridge. A 15DOFs model is assumed for a car in the monorail train. The validity of developed equations of motion for a monorail train-bridge interaction system is verified by comparison with the field-test data. The inertia effect due to a ground motion is combined with the monorail train-bridge interaction system to investigate the seismic response of the monorail bridge under a moving train. An interesting result is that the dynamic system of the train on monorail bridges can act as a damper during earthquakes. The observation of numerical results also points out that the damper effect due to the dynamic system of the monorail train tends to decrease with increasing speed of the train.

Dynamic response of a monorail steel bridge under a moving train

This study proposes a dynamic response analysis procedure for traffic-induced vibration of a monorail bridge and train. Each car in the monorail train is idealized as a dynamic system of 15-degrees-of-freedom. The governing equations of motion for a three-dimensional monorail bridge–train interaction system are derived using Lagrange's formulation for monorail trains, and a finite-element method for modal analysis of monorail bridges. Analytical results on dynamic response of the monorail train and bridge are compared with field-test data in order to verify the validity of the proposed analysis procedure, and a positive correlation is found. An interesting feature of the monorail bridge response is that sway motion is caused by torsional behavior resulting from eccentricity between the shear center of the bridge section and the train load.

Effect of train dynamics on seismic response of steel monorail bridges under moderate ground motion

This study is intended to investigate the seismic response of steel monorail bridges using three-dimensional dynamic response analysis. We particularly consider monorail bridge–train interaction when subjected to ground motion that occurs with high probability. A monorail train car with two bogies with pneumatic tires for running, steering and stabilizing wheels is assumed to be represented sufficiently by a discrete rigid multi-body system with 15 degrees of freedom (DOFs). Bridges are considered as an assemblage of beam elements with 6 DOFs at each node. Modal analysis is used for dynamic response analysis under moderate earthquakes. The seismic response of an advanced monorail bridge that adopts a simplified structural system and composite girders is investigated through comparison with seismic responses of a conventional bridge. The acceleration response of a monorail train is also calculated to investigate the effect of structural types of bridges on the train's dynamic response during earthquakes. Results show that the seismic responses of the advanced bridges are greater than those of the conventional monorail bridge because of the simplified structural system and increased girder weight that is attributable to composite girders of the advanced bridge. Moreover, the train on the advanced bridge shows greater dynamic response than that on the conventional bridge. Observations reveal that the dynamic monorail train system acts as a damper on the monorail bridge. That fact shows that the existing design, which considers a train as additional mass, yields a conservative result. Copyright © 2006 John Wiley & Sons, Ltd.