The Theory and Case Study of Axle Load Identification Based on BWIM of Orthotropic Steel Deck

2012 ◽  
Vol 204-208 ◽  
pp. 1247-1254
Author(s):  
Guang Yang ◽  
Wei Zhen Chen ◽  
Jun Xu
Keyword(s):  
Load Capacity ◽  
Traffic Load ◽  
Actual Condition ◽  
Identification System ◽  
Load Identification ◽  
Load Spectrum ◽  
Orthotropic Steel Deck ◽  
Existing Bridges ◽  
Steel Deck

In China recent accidents of sudden collapses of in-service bridges have aroused great concern about the real traffic load and bearing capacity of existing bridges. The proper management of existing bridges relies on accurate information of bridge operating load which is essential for correct assessment of operation and safety of bridges. An integrated load identification system for operating traffic which is built on characteristics of orthotropic steel deck, that is, the locality of stress influence line of orthotropic steel deck, and is based upon BWIM technique to establish functional relation between axle load and stress history, Case study of stress monitoring was carried out on two truss bridges with orthotropic steel deck under both controlled and normal traffic conditions to verify the system. In the case of controlled traffic, monitored information was used to back calculate axle load. The load information was compared with synchronous video recording of the traffic to check inversely calculated data about wheel weight and its lateral deviation between actual condition, The results show that the established identification system is accurate and valid. In the case of normal traffic, monitored stress data were used to back calculate axle load and wheel lateral distribution. From the results, axle load spectrum is abstracted and can directly help assessment of real load capacity and fatigue life of the bridge.

Traffic loads for the assessment of existing bridges

2021 ◽  
Author(s):  
Vazul Boros ◽  
Roman Lenner ◽  
Alan O'Connor ◽  
Andre Orcesi ◽  
Franziska Schmidt ◽  
...  
Keyword(s):  
Road Traffic ◽  
Traffic Load ◽  
Traffic Loading ◽  
Traffic Loads ◽  
Universal Solution ◽  
Load Effects ◽  
Characteristic Values ◽  
Existing Bridges ◽  
Partial Factor

<p>IABSE TG 1.3 aims to identify appropriate approaches for applications of the partial factor format in assessment of existing bridges. A sub-group was formed to investigate and provide recommendations on updating road traffic loads. Commonly, these are assessed by complex numerical simulations. While this study does not provide a universal solution, it demonstrates by a case study a simple and reasonably conservative way of using simulations to update traffic load effects, meanwhile continuously highlighting the objectives, potential alternatives or pitfalls of simulations. The results indicate that, for the short, single span bridge under consideration, the characteristic values given in Eurocodes provide conservative estimates. The probabilistic model for traffic loading obtained by bridge- and route-specific simulations will yield substantially more favourable reliability levels in comparison to the general model in fib Bulletin 80.</p>

Monitoring of a Norwegian steel-concrete bridge strengthening for composite action

2021 ◽  
Author(s):  
Victor Vestman ◽  
Peter Collin ◽  
Robert Hällmark ◽  
Magnús Arason
Keyword(s):  
Load Capacity ◽  
Design Procedure ◽  
Concrete Bridges ◽  
Traffic Load ◽  
Traffic Density ◽  
Concrete Bridge ◽  
Composite Action ◽  
Shear Connectors ◽  
Coiled Spring ◽  
Existing Bridges

<p>Traffic density and vehicle weight have been increasing over time, which implies that many existing road bridges were not designed for the high service loads and the increased number of load cycles that they are exposed to today. One way to increase the traffic load capacity of non-composite steel- concrete bridges is to use post-install shear connectors and one type of shear connector is the coiled spring pin. This type of connector has advantages for strengthening of existing bridges, since it enables an installation from below while the bridge is still in service and does not bring along removal of concrete and pavement, nor welding to the top flange.</p><p>This paper describes one ~50 years old Norwegian single span steel-concrete bridge that was strengthened with post-installed coiled spring pins. The strengthening method and the design procedure are presented, along with the results from a field monitoring on Sagstu bridge, performed to evaluate the behaviour of the strengthened structure. The results show that the coiled spring pins counteract the slip and bring along a very good degree of composite action.</p>

Drug abuse and drug addiction among students of University of Rajshahi

2020 ◽  
Vol 11 (3) ◽  
pp. 21-32
Author(s):  
Faiqua Tahjiba
Keyword(s):  
Drug Abuse ◽  
Drug Addiction ◽  
Actual Condition ◽  
Snowball Sampling ◽  
Case Study Method ◽  
Monthly Expenditure ◽  
Physical Problems ◽  
Depth Interview ◽  
Research Show

Objectives: The aim of this study was to investigate the actual condition of the students of University of Rajshahi (RU) regarding drug abuse and addiction. Using case study method the research was conducted with four objectives: (a) to find out how respondents began drug abuse; (b) to discover the causes of their drug addiction; (c) to understand the process of their drug abuse; and (d) to find out the economic, social and health effects of drug abuse. Methods: Case study method was used in this research. Through snowball sampling 18 drug- addicted students of RU were selected as respondents. In-depth interview with a schedule was used to collect data from the respondents in January 2019. Results: Findings of the study show that the causes of drug addiction included curiosity, frustration, friends’ request, neglect from family and friends etc. The drugs which they usually abused were Yaba, Phensydyle, Ganja (Weed), Chuani etc. Their average monthly expenditure for collecting drugs was in between Taka 8,000-10,000. They collected those drugs from rickshaw pullers at different points within the campus and from Mizaner Mor, Budhpara slum and other places outside the campus. The respondents opined that drugs were available if sufficient money could be spent. The respondents had senior and junior fellow students and local boys as companions while taking drugs. Most of them faced physical problems after taking drugs, and some of them tried to get rid of this curse of drug addiction. Conclusion: The findings of this research show that the rate of drug addiction among the students of RU was quite alarming. Therefore, all stakeholders including the students, guardians, teachers, university authority, the law makers and law enforcing agencies, researchers, civil society, NGO’s and the state must come forward together to combat this formidable foe.

Automatic identification system data-driven model for analysis of ship domain near bridge-waters

2021 ◽  
pp. 1-22
Author(s):  
Lei Jinyu ◽  
Liu Lei ◽  
Chu Xiumin ◽  
He Wei ◽  
Liu Xinglong ◽  
...  
Keyword(s):  
Least Squares Method ◽  
Automatic Identification ◽  
Identification System ◽  
Collision Risk ◽  
Automatic Identification System ◽  
Domain Models ◽  
System Data ◽  
Quantification Model ◽  
Highly Correlated

Abstract The ship safety domain plays a significant role in collision risk assessment. However, few studies take the practical considerations of implementing this method in the vicinity of bridge-waters into account. Therefore, historical automatic identification system data is utilised to construct and analyse ship domains considering ship–ship and ship–bridge collisions. A method for determining the closest boundary is proposed, and the boundary of the ship domain is fitted by the least squares method. The ship domains near bridge-waters are constructed as ellipse models, the characteristics of which are discussed. Novel fuzzy quaternion ship domain models are established respectively for inland ships and bridge piers, which would assist in the construction of a risk quantification model and the calculation of a grid ship collision index. A case study is carried out on the multi-bridge waterway of the Yangtze River in Wuhan, China. The results show that the size of the ship domain is highly correlated with the ship's speed and length, and analysis of collision risk can reflect the real situation near bridge-waters, which is helpful to demonstrate the application of the ship domain in quantifying the collision risk and to characterise the collision risk distribution near bridge-waters.

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

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