Structural Members In Bridges Research Articles

Estimating the Young’s Modulus of spaghetti with a buckling experiment

The Young’s Modulus of a structural material is a measure of its elasticity and is defined as the ratio
 of the tensile stress to tensile strain. This study aims to investigate a specific property of the material
 qualities of pasta through buckling – Young’s Modulus. Buckling across three pasta diameters and four different lengths is investigated. A force is applied from the top using a finger until buckling was observed and the weight was measured. The values recorded for applied force and other available values were used to determine the Young’s modulus of San Giorgio pasta. The Young’s modulus averaged over the different diameters s 5.07 ± 1.7 GPa. It is unknown how broadly these findings apply since other brands, which may use different recipes, may result in different Young’s Moduli. Ultimately, our results may assist in quality control during manufacture and serve as useful information for the secondary purpose of educational applications of pasta, where the material is used as structural members in bridges, towers, and other engineered objects.

Flexure and shear load rating evaluation of composite bridge superstructure under effect of different trucks load types

The purposes of this study were to provide a methodology for comparing between structural members of composite bridge due to flexure and shear load rating. Also it was used to evaluate and determine the load capacity of composite bridge structural members by adopting load rating analysis method through using different types of international trucks. CSI bridge Ver. 20 was used in the analysis process. The results of flexure and shear, load rating shown that the left and right girders carried the higher values of flexure and shear load rating for all types of trucks load. The structural member of bridge which was subjected to higher values of flexure and shear load rating had sufficient live load carrying capacity, more elasticity and stiffness, indicating that the values of static structural parameters such as bending moment, vertical shear force, vertical displacement and axial force were lower than structural member had minimum values of flexure load rating. The results of factored bending moment, vertical shear force, and axial force shown that truck type LM3-3600/240 had the higher values of factored bending moment, vertical shear force, and axial force within exterior girders which were appeared minimum flexure load rating. The minor values of factored bending moment, vertical shear force, and axial force were happened under effect of truck type AML and Hsn-44L because of these trucks had higher flexure and shear load rating. The maximum value of vertical displacement was 29 mm under truck type LM3-3600/240 which had lower flexure load rating.

Designing steel bridges for fire safety

While bridge fires can often lead to substantial losses, current codes and standards do not specify any provisions for fire resistance of load bearing structural members in bridges. In order to bridge this knowledge gap, this study presents a practical approach to overcome fire hazard in steel bridges of critical nature. The proposed approach comprises of two components namely, analytical and numerical. In the analytical component, fire risk in a steel bridge is assessed, through a specially derived fire-based importance factor that allows estimating vulnerability of a bridge to fire hazard. The second component integrates both simplified calculation method as well as highly nonlinear numerical analysis through a coupled finite element (FE) based simulation with the purpose of developing relevant strategies for mitigating fire risk and losses. The applicability of this approach is illustrated herein through a comprehensive case study on an actual steel bridge that underwent an intense fire incident. The aim of this study is first to present engineers and designers with a practical tool to identify steel bridges vulnerable to fire hazard and secondly to guide them into developing optimum solutions to mitigate large fire losses.

Effect of temperature and cooling regime on mechanical properties of high‐strength low‐alloy steel

SUMMARYThis paper presents results from experimental studies on the effect of temperature on mechanical properties of high‐strength low‐alloy ASTM A572 steel commonly used in structural members in bridges. A set of high‐temperature tensile strength tests and post‐temperature exposed residual strength tests is carried out on ASTM A572 steel coupons in 20–1000 °C temperature range. The residual strength tests on high‐temperature exposed steel coupons are carried out after subjecting the coupons to two methods of cooling, namely, air cooling and water quenching. Results from these tests indicate that temperature‐dependent strength and stiffness degradation in A572 steel follow the same trend as that of carbon steel but with some variations. A572 steel recovers almost 100% of its room temperature yield strength when heated to temperature up to 600 °C, regardless of the method of cooling, while the extent of strength degradation in coupons subjected to heating beyond 600 °C is dependent on heated temperature and method of cooling. Data generated in these tests are utilized to generate high‐temperature stress–strain and residual stress–strain response of A572 steel. These results are also utilized to propose temperature‐dependent strength, elastic modules, and residual strength reduction factors of A572 steel, which can be used in evaluating residual response of fire‐exposed steel structures. Copyright © 2015 John Wiley & Sons, Ltd.

Finite Element Analysis of Composite Beam with Shear Connectors

Composite structures consisting of concrete slab and rolled up steel sections are widely used structural members in bridges and high rise buildings. The composite action is established by connecting the concrete slab and the steel section by using shear connectors. In this paper, four different types of shear connectors have been analyzed and the best connector for a particular composite beam has been evaluated based on its performance under static load keeping the loading and the amount of steel in the connector as a common aspect.

A probabilistic assessment for classification of bridges against fire hazard

This paper presents the development of a simplified approach for classification of bridges based on fire hazard. Statistical data from recent fires in bridges is utilized to quantify the probable risk of fire in bridges and also probability of fire-induced collapse of structural members in bridges. An importance factor is derived for identifying the vulnerability of bridges to fire hazard. The proposed importance factor, developed using weighted factor approach, takes into account the degree of vulnerability of different bridge components, critical nature of a bridge from traffic functionality point and fire mitigation strategies present in a specific bridge. The proposed importance factor for fire design, which is similar to the one currently used for evaluating wind, and snow loading in buildings, is validated against previous bridge fire incidents. It is shown through this validation that the proposed method for importance factor can be used as a practical tool for identifying critical bridges from the point of fire hazard.

Evaluating Fire Resistance of Steel Girders in Bridges

In current practice, no special measures are applied for enhancing structural fire safety of steel bridge girders. Further, there is very limited information and research data in the literature on the fire resistance of structural members in bridges. In this paper, the fire response of a steel bridge girder under different conditions is evaluated using the FEM computer program ANSYS. In the analysis, the critical factors that influence fire resistance, namely, fire scenario, fire insulation, and composite action arising from steel-concrete interaction, are accounted for. Results from numerical studies show that the composite action arising from steel-girder-concrete-slab interaction significantly enhances the structuralperformance(and fireresistance)ofasteelbridgegirderunder fireconditions.Othersignificantfactorsthatinfluence fireresistanceof steel bridge girders are fire insulation and type of fire scenario. DOI: 10.1061/(ASCE)BE.1943-5592.0000412. © 2013 American Society of Civil Engineers. CE Database subject headings: Fires; Fire resistance; Girder bridges; Steel bridges. Author keywords: Bridge fires; Fire resistance; Steel girders; FEM analysis.

Experimental Analysis and Performance Evaluation of Fu Feng Highway Prestressed Concrete Bridge after Strengthening in China

Fu Feng highway prestressed concrete bridge is located in Changchun City which is the capital and largest city of Jilin province and it located in the northeast of China. The strengthening of the bridge structural members can be attempted by replacing poor quality or defective materials by better quality materials, attaching additional load-bearing materials, and re-distribution of the loading actions through imposed deformation on the structure system. The objectives of this study are to explain the strengthening process of damaged structural members of Fu Feng bridge, and to evaluate the performance of the bridge structure by adopting static load test. The strengthening process of damaged structural members includes three stages. These stages include the strengthening of box girders floor by casting of 10cm of reinforced concrete in the floor of box girder within the location of positive bending moment in the mid-span and edge span, the strengthening of box girders web by pasting steel plates in the inside of the right and left of box girders, and the strengthening of the transverse beam of piers No. 18 and No. 19 by using carbon fiber sheet. The results of static load test show that the values of testing coefficient ( ) of stress range from 0.83 to 0.92 are less than allowable value 1.05. Therefore, these values satisfy the allowable value of standard, indicating that the structural member has a certain strength reserve and the working state of the bridge structure in good state. the ratio between the measured and theoretical deflection is 1.41 and 1.68 for condition 3 more than allowable value 0.8, indicating that the state of stiffness is not good and there are still a serious shortage in stiffness of structure. Therefore, this study recommended that the bridge structural members need to re-strengthen by using other effective technical and materials to increase the stiffness of structural members of the bridge.

Alexandre Gustave Eiffel: An engineer scientist

Eiffel is best remembered for engineering the tower that is a Paris landmark and bears his name. However, Eiffel has many other firsts to his credit. He was one of the first to experimentally obtain material properties of wrought iron that permitted him to proportion structural members in bridges and buildings that he built to sustain the service loads experienced by them. Having struggled to get a good estimate of wind forces on the many tall structures that he designed and constructed during his career, Eiffel was among the first to experimentally obtain data on fluid flow around an object and establish accurately the drag on a body dropped in air in his later years. He developed one of the earliest versions of the ‘wind tunnel’ that today plays a pivotal role in aerodynamic studies. This article traces the evolution of Alexandre Gustave Eiffel as an engineer and scientist.

Retrofit of Square Concrete Columns with Carbon Fiber-Reinforced Polymer for Seismic Resistance

This paper investigates the prospect of strengthening deficient and repairing damaged square reinforced concrete columns with carbon fiber-reinforced polymer (CFRP) jackets. 8 specimens representative of structural members in bridges constructed prior to 1971 consisted of a 305 x 305 x 1473 mm column connected to a 508 x 762 x 813 mm stub. Each 900 kg specimen was tested under lateral cyclic displacement excursions and simultaneous constant axial load to simulate seismic forces. Results indicate that added confinement with CFRP at critical locations enhanced ductility, energy dissipation capacity, and strength of all substandard members. A positive relationship prevailed between favorable behavior and increasing reinforcement layers while improvements realized through CFRP repair declined as damage level prior to retrofit increased. Appropriately strengthened specimens also exceeded the performance of comparable columns with adequate seismic lateral reinforcement.