Bridge Approach Research Articles

Malaysia seismic provision design standard approach for bridges

Malaysia seismic provision design standard approach for bridges

Evaluation of Drainage System on Jalan Slamet Riyadi and the Mahakam IV Bridge Approach Road, Samarinda City

The construction of the Mahakam IV Bridge and the geometric changes to the Slamet Riyadi road in the vicinity have caused inundation problems on the main road section and the Mahakam IV Bridge Approach Road on the Samarinda City side. It is necessary to evaluate the drainage system in that location to prevent inundation that disturbs traffic and causes road damage. Flood discharge is analyzed based on rainfall data and using a Modified Rational Method. The design rain is calculated by a method that satisfies the goodness of fit test. The evaluation results show that the flood discharge to the channel is greater than the capacity channel. An alternative solution is to add a direct flow path to the Mahakam River in the form of long storage. And to speed up the drying on the bridge approach road, it is necessary to increase the number of street inlets and repair the culverts that drain water to the Mahakam River

Soft ground improvement below bridge approach foundation using cement deep mixing columns combined with geotextile

Vehicle load is a dynamic load and embankment load is a static load. These two load types can act simultaneously to accelerate the consolidation rate of the ground under the embankment, which then leads to differential settlement. This differential settlement is dangerous as it can cause sudden bouncing and shock for vehicles on the road. There are also other problems such as the reduction in the exploitation capacity of the construction work due to the reduction in the speed of vehicles going through the positions of settlement. Lower speed increases the waste of means of transport. Excessive settlement can occur from reasons such as improper design or improper construction. This paper uses the finite element method to simulate the construction process of the bridge approach to calculate, and check the stability and deformation of the soft ground under this road. The analysis results show that the settlement of the ground without treatment is quite large at 1.06 m. After reinforcement, the settlement is 0.013 m, and the stability coefficient increases from 1.032 to 2.739. The research results can be applied to reinforce the bridge approach with a system of cement deep mixing (CDM) columns combined with geotextiles to shorten the construction time and limit settlement compensation.

Transfer Learning to Enhance the Damage Detection Performance in Bridges When Using Numerical Models

Classifiers based on machine learning algorithms trained through hybrid strategies have been proposed for structural health monitoring (SHM) of bridges. Hybrid strategies use numerical and monitoring data together to improve the learning process of the algorithms. The numerical models, such as finite-element (FE) models, are used for data augmentation based on the assumption of the existence of limited experimental data sets. However, a numerical model might fail in providing reliable data, as its parameters might not share the same underlying operating conditions observed in real situations. Meanwhile, the concept of transfer learning has evolved in SHM, in particular through domain adaptation techniques. The ability to adapt a classifier built on a well-known labeled data set to a new scenario with an unlabeled data set is an opportunity to transit bridge SHM from research to practice. Therefore, this paper proposes an unsupervised transfer learning approach for bridges with a domain adaptation technique, where classifiers are trained only with labeled data generated from FE models (source domain). Then, unlabeled monitoring data (target domain) are used to test the classification performance. As numerical and monitoring data are related to the same bridge, both domains are assumed to have similar statistical distributions, with slight differences caused by the uncertainties inherent to the FE models. The domain adaptation is performed using a transfer knowledge method called transfer component analysis, which transforms damage-sensitive features from the original space to a new one, called latent space, where the differences between feature distributions are reduced. This approach may increase the use of numerical modeling for long-term monitoring, as it overcomes some of the limitations imposed by the calibration process of FE models. The efficiency of this unsupervised approach is illustrated through the classification performance of classifiers built on source data with and without domain adaptation, and using the benchmark data sets from the Z-24 Bridge as the target data.

Adhesive performance and impermeability mechanism of loess embankment using caster oil based polyurethane reinforce

Loess subgrade is easy susceptible to moisture damage, especially in the embankment at the bridge approach. In order to decrease the differential settlement, Caster oil-based polyurethane (COP) was used to reinforce the loess embankment. The adhesive performance and impermeability mechanism of COP reinforced loess embankment using grouting technology were investigated. The adhesive force of COP reinforced loess embankment is bigger than tranditional polyurethane (1.5 MPa). The bond strength of loess embankment sample is very low and lower than 0.15 MPa, while the bond strength of COP reinforced loess embankment sample is bigger than 0.32 MPa. The adhesive performance results showed that COP could improve the wet resistance and adhesive performance of loess embankment. The new permeability model of COP was proposed and it showed that the loess particles were covered by COP with the addition of COP and water can not immer into the loess pores, and COP permeability appeared gradient and consisted with diffusion, permeate, and compaction three stages. Firstly, the COP grouting material fills the void of soil to form a cylinder and form a network structure. Then squeeze the broken loose soil to form a semicircular projection, forming the water stop channel; Finally, the dense soil is split to form a cone, forming the COP-loess soil consolidation.

THE IMPACT OF UNEVEN JOINT OF BRIDGE APPROACH SLAB AND DECK TO ROAD USERS PERCEPTION AND SPEED: A CASE STUDY IN JAMBATAN PARIT JAMIL AND JAMBATAN PARIT HAJI IBRAHIM, JOHOR

Bridge approaches offered a smooth and safe transition for any vehicle from the road pavement to the bridge structure and vice versa. Settlement of the soil that of Jambatan Parit Jamil results in a slight change of their level which can create a ‘bump’ on the roadway. This uneven joint occurs due to soil settlement under the bridge approach due to the increasing number of rough rides by the driver that cause cracking at the approach slab. Thus, the ‘bump’ or uneven joint between the bridge deck and road pavement will cause driver discomfort, impair driver safety, reduce steering response, and. The purpose of this study is to investigate the perception of the respondents about the shock impact and to evaluate their speed reduction during maneuvering the uneven joint of the approach slab and the bridge deck. Thus, a social survey has been conducted in Kampung Parit Jamil and Kampung Parit Penyengat to investigate the perception of frequent road users about uneven joints. The spot speed study method has been used to evaluate vehicle speed reduction in maneuvering the uneven joint. The speed reduction results were then compared with the speed of vehicles on a good condition bridge as a control sample. The results show that most of the respondents suggest that they are ‘very disturbed’ (70%) with uneven joint. The speed reduction on the uneven joint bridge recorded 13km/h mean speed readings of 13 km / h and possess 5km/h differences with a good condition bridge. The results are expected to highlight the impact of uneven joint issue on road users’ comfort and traffic speed.

Effect of rail axle load on geosynthetic reinforced back-to-back mechanically stabilized earth walls: Experimental and numerical studies

Back-to-back Mechanically Stabilized Earth (BBMSE) walls are generally used in approach embankments of flyovers and bridges. The complex geometry of two interactive MSE walls in a single structure makes it a special case for the study. This paper presents the performance evaluation of unconnected, connected and overlapped geogrid reinforced back-to-back mechanically stabilized earth walls supporting the railway tracks at bridge approaches. Scaled model tests were conducted to study the behaviour of BBMSE walls. Overburden (OB) waste generated from coal mining was used as the sustainable backfill. 3D Finite Element analysis was carried out to validate the model test. A parametric study was also carried out on varying W/H ratio, overlapping length, connected and unconnected geogrid reinforcement, geogrid stiffness and spacing. Train bogie load with its eight-point load was used as a loading condition. Lateral, vertical deformations of walls, geogrid strain, maximum tensile force developed in the geogrid for all the cases were investigated and discussed in detail. Geogrid arrangements were found to be critical in reducing the wall displacement. The overlapping length of the geogrid resulted in lesser deformation with the deformation reduction of 58 % compared to the connected geogrid.

Use of geosynthetic reinforced soil-integrated bridge system to alleviate settlement problems at bridge approach: A review

Bump problems at the bridge approach cause riding discomfort and result in safety issue to the road users. The Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) is a recent bridge approach construction system that connects the bridge deck and roadways without joints and bearings, thus capable to eliminate the bump problems. This system is gaining popularity for low to medium bridge construction due to its relatively faster, lower cost, and simple construction process. The GRS abutment is a composite geotechnical structure with internally supported reinforcement. A close spacing reinforcement of 0.2–0.3 m in between the compacted granular backfill of high shear resistance has improved the bearing capacity of the GRS abutment, hence capable to support the bridge loads directly. In this paper, a thematic literature review on the bump problems and GRS-IBS system is presented. Summaries of previous studies are tabulated and discussed, inclusive of case studies, physical models, numerical models, and key factors affecting the performance of GRS-IBS. Limitations posed to this system are also provided at the end of this article. The review and summary of this paper are expected to provide meaningful information to the readers.

Feasibility Study of Locally Excavated Soil in Foamed Cement Mixture as Backfill Material for Abutments of Railway Bridges

Abstract The varying stiffness of materials surrounding a railway bridge abutment section has caused concern for rapid deterioration. Particularly on the transition toward the bridge approach, a significant contributing factor to the bad experience is the consolidation of the backfill material used. The objective of this study is to conduct experimental research utilizing locally available soil in a lightweight foamed concrete mixture as an alternative sustainable solution. The new technique combines the merits of the self-leveling air foam and the early strength attainment of portland cement concatenate into a flowable soil mixture. To attain this objective, the properties of the flowable soil mixture are tested by using various laboratory experiments. Furthermore, a numerical simulation was utilized to evaluate the performance of the backfill material under cyclic train loads compared with the conventional cement-treated base. The test results suggested that air foam content noticeably improves the self-leveling of backfill material, however, it should be controlled at lower than 20 % to ensure sufficient strength gain. Adding more cement content and lowering the usage of air foam not only shortens the setting time to less than 12 h and enhances the compressive strength up to 1.45 MPa, but it also reinforces the frost resistance of the lightweight foamed soil mixture. In addition to the numerical simulation, the test results reveal that the new material provides great settlement resistance and can withstand vibration load for a railway track system. The elastic displacement can be reduced up to 21 % (2 mm), and the plastic settlement can be lower to more than 60 % (6 mm) under 10,000 cyclic loads. In general, the application of lightweight foamed soil mixture as a backfill material for railway bridge approach poses a green and sustainable alternative solution.

Damage Detection Approach for Bridges under Temperature Effects using Gaussian Process Regression Trained with Hybrid Data

The success of detecting damage robustly relies on the availability of long periods of past data covering multiple weather scenarios and on the information contained in the data used during the learning process. Thus, the innovation of this paper is to apply a hybrid data set to train a Gaussian process regression, assuming a practically plausible range of environmental conditions. The proposed model presents a satisfactory performance to detect damage when structural changes caused by damage are blurred with changes caused by temperature. Rather than relying exclusively on experimental data, this strategy use finite-element models to generate complementary data when the structure is undamaged under a broad spectrum of temperature variations that are not measured. Once the stochastic interpolation is defined, the damage detection model is tested using experimental data considering different damage levels and temperature conditions. Induced settlements of a bridge pier are used as realistic damage scenarios. The Z24 prestressed concrete highway bridge in Switzerland is used to demonstrate the applicability of the proposed strategy.

A Response-Type Road Anomaly Detection and Evaluation Method for Steady Driving of Automated Vehicles

Serious Road anomalies caused by bridge approach settlement, pavement rutting, etc., not only seriously affect traffic safety and user experience but also aggravate the damage of road structure. It is more relevant to automated vehicles (AVs) as they are currently not designed to measure the pavement roughness directly. Without prior-collected road anomalies information, AVs’ active suspension control system can only passively reduce the negative impact of road anomalies to a certain extent. This paper proposed a response-type road anomaly detection and evaluation method by collecting the vibration data from AVs. A mechanical estimation model for the height of anomaly (HoA) is constructed to evaluate the degree of road anomaly. Passenger’s comfort is evaluated by three featured indicators: maximal acceleration, weighted root-mean-square acceleration, and jerk. A full-car simulation model is programmed based on the Simulink platform to reveal the relationship among road anomalies, comfort, and speed, which helps design a steady driving velocity profile for AVs. The results show that the root-mean-square error of road anomalies estimation is about 0.63cm. AVs’ comfort can be improved significantly by employing the proposed steady driving strategies.

Sparse estimation of historical functional linear models with a nested group bridge approach

AbstractThe conventional historical functional linear model relates the current value of the functional response at time to all past values of the functional covariate up to time . Motivated by situations where it is more reasonable to assume that only recent, instead of all, past values of the functional covariate have an impact on the functional response, in this work we investigate the historical functional linear model with an unknown forward time lag into the history. In addition to estimating the bivariate regression coefficient function, we also aim to identify the historical time lag from the data, which is important in many applications. To this end, we propose an estimation procedure that uses the finite element method to conform naturally to the trapezoidal domain of the bivariate coefficient function. We use a nested group bridge penalty to facilitate simultaneous estimation of the bivariate coefficient function and the historical lag, and show that our proposed estimators are consistent. We demonstrate this method of estimation in a real data example investigating the effect of muscle activation recorded via the noninvasive electromyography (EMG) method on lip acceleration during speech production. In addition, we examine the finite sample performance of our proposed method in comparison with the conventional approach to estimation via simulation studies.

Emissions, puffing topography, mouth level exposure and consumption among Japanese users of tobacco heated products

<p><strong>Background:</strong> Tobacco heating products (THPs), which heat rather than burn tobacco, have been demonstrated by a number of studies to produce an aerosol with substantially lower levels of toxicants and reduced cytotoxicity relative to cigarette smoke. As they evolve in design and function, however, it is important to verify that variant THPs maintain sufficient equivalence to the original product if we are to leverage existing foundational datasets. Recent studies suggest that a bridging approach, in which a variant is shown to be comparable to the original product on which a large foundational dataset has been generated, might be used to ensure that the same product-related claims apply.</p><p><strong>Methods:</strong> In this study, emissions and consumer behaviour were assessed for two variants of glo<sup>TM</sup> THPs: an extensively tested glo<sup>TM</sup> type 1 (glo 2.0), and glo<sup>TM</sup> type 3 (glo hyper) in base and boost modes. Emissions testing was conducted by measuring the percentage reduction of TobReg9 toxicants, relative to a 1R6F reference cigarette.</p><p><strong>Results:</strong> Consumer behaviour, including puffing topography, average daily consumption (ADC) and mouth level exposure (MLE) to NFDPM and nicotine was measured among 63 regular glo<sup>TM</sup> users in Tokyo, Japan. Emissions testing showed a substantial reduction in TobReg9 toxicants compared to the reference cigarette (95.5-97.3%), whilst there were no substantial differences in the ADC, puffing behaviour or MLE among the three THPs.</p><p><strong>Conclusions</strong>: Emissions analysis based on TobReg9 toxicants and consumer behaviour data provide evidence that the glo<sup>TM</sup> type 3 is comparable to glo<sup>TM</sup> type 1, indicating the possibility of using a bridging approach for the analysis of variant THPs based on use behaviour alone.</p>

Radiotherapy as a Bridging Approach in High-Grade B-Cell Lymphomas before CD19-Targeted CAR T-Cell Therapy

<h3>Purpose/Objective(s)</h3> To evaluate the safety and efficacy of bridging radiation therapy (RT) in patients with relapsed/refractory high-grade B cell lymphomas (HGBCL) undergoing CD19-targeted chimeric antigen receptor (CAR) T-cell therapy. <h3>Materials/Methods</h3> A multi-institutional retrospective study was performed for 352 patients with HGBCL treated with CAR T-cell therapy. 140 of 352 patients (40%) received bridging therapy prior to CAR T infusion: systemic therapy alone in 98 patients, and RT +/- systemic therapy in 42 patients. This report focuses on the outcome of the 42 patients who received bridging RT. Overall survival (OS) from the date of CAR T infusion was estimated with the Kaplan-Meier method. The time to in-field progression was defined as the time from the start date of bridging RT until the time of in-field progression. <h3>Results</h3> The median follow-up from the date of CAR T infusion was 5.2 months (range, 9 days-33.6 months). Thirty-four patients (81%) received RT within 30 days of CAR T infusion, while 8 patients (19%) received RT at least 30 days before infusion. The most common indication for bridging RT was symptomatic local progression, with 16 patients starting RT prior to apheresis due to clinical urgency. Sites of RT include: head and neck (12), central nervous system (8), chest (5), pelvis (5), abdomen (4), extremities (2), paraspinal area (3), and multiple sites (3). The median dose/fractionation were 24 Gy (range, 8-37.5 Gy) and 8 fractions (range, 2-15 fractions). Three patients (7%) had in-field progression at a median time of 3.2 months (range, 1.2-4.6 months), all of whom had bulky disease (≥5 cm) at the time of apheresis. Superior median OS was observed among the 38 patients (90%) who achieved objective in-field responses after bridging-RT (25.6 months vs. 2.1 months; p=<0.001). Only 2 patients experienced grade 3-4 RT-related toxicities. <h3>Conclusion</h3> Our data supports that RT is an effective bridging approach for patients with locally progressive HGBCL prior to CAR T-cell therapy. It is associated with limited toxicity, and offers excellent in-field control in the immediate post-CAR T timeframe. Patients with in-field response to bridging RT have significantly better survival outcome.

Mixed-lanthanide clusters: A bridging approach that permits the design of molecular magnetic materials by introducing heavy lanthanides into the 3d-light lanthanide clusters without breaking structural integrity

Theoretical studies suggest that the ring 3d-4f clusters {MnIII4Ln4} may be a good material for magnetic refrigeration. However, only {MnIII4Ln4} constructed from light lanthanide ions have been obtained, while the attempt for their analogue containing the magnetically isotropic Gd(III) ions has failed. By applying the strategy of synthesizing mixed-lanthanide clusters, mixed-lanthanide clusters {MnIII4LaxGd4-x} and {MnIII4NdxGd4-x} without breaking structural integrity of {MnIII4Ln4} have been successfully made. It is found that smaller ionic radius difference between the lanthanides tends to increase the introduction of Gd(III) when applying the strategy. Moreover, the magnetic property measurements show that the obtained mixed-lanthanide clusters exhibit magnetothermal effect as predicted.

Surgical Unroofing of Myocardial Bridges

•Surgical unroofing via standard median sternotomy or minimally invasive approaches stands as an effective treatment for symptomatic and hemodynamically significant myocardial bridges. Myocardial bridges (MB) are a congenital variant in which an epicardial coronary artery—most commonly the left anterior descending (LAD)—is contained within an intramyocardial segment. The clinical significance of this lesion varies from no symptoms to debilitating angina, ventricular arrhythmia, and even sudden cardiac arrest. Traditionally difficult to diagnose, symptomatic myocardial bridges remain an elusive entity with a lack of clarity regarding medical treatment and surgical indications. Importantly, studies have shown that with appropriate patient selection, MB unroofing is an effective treatment for symptomatic lesions, in both the adult and pediatric populations. This article describes the preoperative evaluation and the surgical approach for myocardial bridges. Myocardial bridges (MB) are a congenital variant in which an epicardial coronary artery—most commonly the left anterior descending (LAD)—is contained within an intramyocardial segment. The clinical significance of this lesion varies from no symptoms to debilitating angina, ventricular arrhythmia, and even sudden cardiac arrest Traditionally difficult to diagnose, symptomatic myocardial bridges remain an elusive entity with a lack of clarity regarding medical treatment and surgical indications. Importantly, studies have shown that with appropriate patient selection, MB unroofing is an effective treatment for symptomatic lesions, in both the adult and pediatric populations. This article describes the pre-operative evaluation and the surgical approach for myocardial bridges. Myocardial bridges (MB) are a congenital variant in which an epicardial coronary artery—most commonly the left anterior descending (LAD)—is contained within an intramyocardial segment. The clinical significance of this lesion varies from no symptoms to debilitating angina, ventricular arrhythmia, and even sudden cardiac arrest Traditionally difficult to diagnose, symptomatic myocardial bridges remain an elusive entity with a lack of clarity regarding medical treatment and surgical indications. Importantly, studies have shown that with appropriate patient selection, MB unroofing is an effective treatment for symptomatic lesions, in both the adult and pediatric populations. This article describes the pre-operative evaluation and the surgical approach for myocardial bridges.

A macro-modelling continuum approach with embedded discontinuities for the assessment of masonry arch bridges under earthquake loading

The paper presents a novel effective macro-modelling approach for masonry arches and bridges under cyclic loading, including dynamic actions induced by earthquakes. It utilises an anisotropic material model with embedded discontinuities to represent masonry nonlinearities. Realistic numerical simulations of masonry arch bridges under static and dynamic loading require accurate models representing the anisotropic nature of masonry and material nonlinearity due to opening and closure of tensile cracks and shear sliding along mortar joints. The proposed 3D modelling approach allows for masonry bond via simple calibration, and enables the representation of tensile cracking, crushing and shear damage in the brickwork. A two-scale representation is adopted, where 3D continuum elements at the structural scale are linked to embedded nonlinear interfaces representing the meso-structure of the material. The potential and accuracy of the proposed approach are shown in numerical examples and comparisons against physical experiments on masonry arches and bridges under cyclic static and dynamic loading.

Synthesis of Bridge Approach Slab Behavior, Design, and Construction Practice

Synthesis of Bridge Approach Slab Behavior, Design, and Construction Practice

Social entrepreneurs’ use of spatial bricolage to create frugal innovation in a divided urban setting

This study examines how social entrepreneurs mobilize resources to innovate in divided urban settings. Over a period of two years, we followed four social start-up entrepreneurs in the city of Cape Town, South Africa, characterized by some of the highest inequality levels in the world. We analyzed how social entrepreneurs navigate this urban divided context to mobilize resources from both resource-affluent and resource-constrained spaces to achieve innovation. Our findings suggest that these entrepreneurs use bridging and building approaches that cross over between spatial and digital spaces. Specifically, we discovered that social entrepreneurs mobilize resources using four distinct types of spaces and observed that they make use of these very spaces in their bricolage, hence expanding their portfolio of resources at hand. Based in our analysis, we build on the recently introduced concept of spatial bricolage to develop the notion of spatial awareness. By identifying a link between spatial awareness and frugal innovation, we contribute to the literature on social entrepreneurship and innovation in the African context.

Three-dimensional pore-scale simulation of non-equilibrium in a two-layer porous burner

A pore-scale numerical simulation for combustion of methane-air mixtures in a two-layer porous media burner made of staggered arrangement of connected particles is preformed. Combustion is modeled by a one-step reaction mechanism, and solid surface radiation heat transfer is computed by discrete ordinates (DO) model. The bridge approach is used to deal with the point contact between adjacent particles. The present study is intended to investigate the non-equilibrium characteristics of gas velocity and temperature under two operating parameters such as the inlet velocity and equivalence ratio. A comparison of the numerical values and experimental values was carried out to prove the effectiveness of numerical model, and a good agreement is shown. The results showed considerable non-equilibrium of velocity and temperature along the space coordinate due to the inhomogeneous porous structure. The extent of flow non-equilibrium increases as inlet velocity and equivalence ratio are increased. The extent of gas temperature non-equilibrium decreases slightly with the inlet velocity, but the equivalence ratio effect on thermal non-equilibrium can be neglected.