Span Bridges Research Articles

Structural Optimization of Simple Span Bridge by Adding Truss Structure

Structural Optimization of Simple Span Bridge by Adding Truss Structure

An analysis of the mantle structure of the Safavid bridge span (Case Study: Thirty Bridges, Marnan, Khaju, Joey)

The purpose of this study was to investigate the correlation between the design of crater width, crater height and base widths of four poles, thirty three bridges, Khajou, Joey, and Marnan, constructed on the Zayandehrood River, and to explore the relationship between these variables underpins the theory that The form of these bridges is a direct function of their main function.In this study, due to the high volume of data, the research method is based on Python coding and working with artificial intelligence algorithms that, after harvesting the required data and performing various calculations of the files in CSV format, and then considering field harvesting, openings Four bridges were simulated in related software using the cosine relation of all openings and plots were plotted.The findings of this study suggest that there is a high similarity and a close relationship between the width and height of the craters on each bridge with that bridge itself and the three other bridges on the river, and the design of these bridges is less than a century old despite historical differences. , Fully functional and based on the technology of that era, the volume of water generated and the stability of the river.In conclusion, it should be noted that the longer the historical period of bridge construction, the greater the width of the bridges, and according to the diagrams of the drawings of each bridge, the design and construction accuracy is high, as well as the 75 openings in the 92 openings in these four bridges. With a similarity percentage of 70 to 90, it has the similarity of 33 bridges and very high bridges, and the lowest bridges and 33 bridges. The bridges are designed based on its performance and according to the standards of that era, construction technology.

Experimental Estimation of the Elastic Modulus of Concrete Girders from Drive-By Inspections with Force-Balance Accelerometers

Parametric identification of bridges using instrumented vehicles can be challenging, mainly due to the reduced length of the time series associated with the bridge span under test. This research discusses the practicability of a time-domain identification method based on the use of an instrumented vehicle. The highest cross-correlation between the bridge response from an elementary analytical model and the experimental one, acquired by a moving force-balance accelerometer, yields the unknown model parameter. The effect of vehicle-bridge interaction is removed by proper filtering of the signals. Specifically, the authors estimate the elastic moduli of seven prestressed concrete bridges and compare a subset of the results to the outcomes of static load tests carried out on the same bridges. There is a good correlation between the elastic moduli from the instrumented vehicle and those from static load tests: the method grasps the approximate value of the elastic modulus of concrete. Still, the data do not return an excellent match due to the bias in the estimation of the deflection shape—the paper remarks on the issues faced during the experimental tests and proposes possible enhancements of these procedures.

Stiffness Estimation of Girder Bridges Using Influence Lines Identified from Vehicle-Induced Structural Responses

The influence line is an important static property in bridges. The shape and magnitude of the girder bridge influence line contain stiffness information for the bridge supports and beam. This research sought to directly identify the rotational stiffness of bridge supports and the flexural stiffness of beams from extracted influence lines, which provides a quantification method for bridge damage and performance degradation. The paper first reviews the influence line identification method from vehicle-induced bridge responses. Then, the complete theoretical formulations of the deflection, rotation, and strain influence line for a general girder bridge are derived. Based on these derivations, the rotational stiffness at two supports and the equivalent flexural stiffness value of the beam are identified. Next, a certain span of a continuous girder bridge is converted to an equivalent simply supported system, and the flexural stiffness distribution of the beam is estimated based on the bending moment-curvature relationship and Betti’s law. The paper then presents a three-span continuous girder bridge verification example. The stiffness estimation results under different test conditions combined with the bridge influence line identification algorithm are presented to verify the reliability of the proposed method. This stiffness estimation method can be applied to baseline-free bridge performance evaluations based on vehicle-induced bridge responses.

Elaboration of weatherproof steel 06гн3мд for structures of bridges exploited in coastal zone

At present decreasing of costs and increasing of efficiency are the most priority directions in any industry. Developing in this way, JSC “Ural steel” together with FGUP “CNIIchermet after I.P. Barding” had mastered production of sheet metal product with increased resistivity against atmosphere corrosion made of steel 14ХГНДЦ for construction of bridges. Because of specific chemical composition of the steel, in the process of metal structures running in the open air, a solid strong oxide film is formed on the metal of the structures which prevents further corrosion without painting. For bridge builders elimination of costly operation of painting of span structures will enable to decrease considerably the costs of bridges construction and running. Having many advantages, steel 14ХГНДЦ has some restrictions in applications for steel structures without painting, as follows: - in sea zone according to domestic norms no close than 500 m from coastline; - in case of disorderly conditions of protective film formation and/or application of salt solutions for surface cleaning (as a rule the restrictions refer to traffic area of bridge span). In view of that for JSC “Ural Steel”, as the leading producer of bridge steel in Russia, an actual task erose: to elaborate and create a weatherproof steel, which could not only operate the whole period of a bridge running without additional protection at bridges con­struction through sea areas or close to coastline, but also withstand severe climate conditions of our country, including areas of High North with temperature lower -50°С. To solve the task together with OJSC “Institute Giprostroymost” and JSC BNIIZhT, a research work was accomplished to elaborate a system of alloying new steel 06ГН3МД with nickel content ~3.0 %, as well as production modes ensuring required corrosion resistance for operation in sea zone. Results of laboratory studies of the new weatherproof steel 06ГН3МД for application in bridge structures for coastal conditions and sea areas presented. Results of mechanical, technological, corrosion as well as fatigue tests of rolling products of the elaborated steel presented. It was established by laboratory studies that the new steel is weatherproofed and ensures lower corrosion losses, higher impact toughness at negative temperatures and plasticity comparing with steels used at present. It was shown that the strength class, technology and modes of factory welding of steel 06ГН3МД meet the requirements to steel span structures of bridges. Base on the results of the studies, the chemical composition of the steel 06ГН3МД was specified, as well as modes of heat treatment, ensuring the required characteristics with significant acceding. It was established that samples of the new steel 06ГН3МД showed considerably higher corrosion resistance - in average by 20% comparing with steel 14ХГНДЦ. At that corrosion resistance tests of welded joints of the new steel showed even higher resistance of the seam comparing with the basic metal, which speaks about quality selection of welding modes and welding materials.

Relationship between the Dynamic Parameters of a Structure’s Vibration Process and the Loading Model Moving on a Bridge

A sufficiently strict conduction of supervision during bridge operation is a crucial matter for many countries, including the underdeveloped country of Viet Nam. In recent times, the budgets in developed countries used for funding the implementation of quality-assessment procedures are quite high compared to the lower budgets in underdeveloped countries. The plan proposed in this work addresses the current lack of information available in the process of structure-quality evaluation. The vibration signals will be acquired from the random circulation status to determine the structure’s behavior so as to utilize the signal information during the bridge span’s operation. The study’s main goal is to find various parameters that can be used to evaluate the actual bridge performance. These parameters must meet certain criteria, such as high sensitivity, low measurement cost, and efficiency in the measurement process, but must not affect the itinerary of vehicles moving on the bridge. The actual structural vibration signals used in this work currently serve as a best trend model for evaluating the operation of the bridge span structure. This study will focus on determining the relationship among deflection, acceleration, and vehicle load so as to evaluate the structure’s working process. This study has also fabricated an experimental model to evaluate and test the sensitivity of the parameters utilized in this study in order to verify the results obtained. The results obtained in this research will be applied for the quality-control process in several bridge models with span structures built with the composite steel concrete cross section of the beam. Many developing countries, including Viet Nam, will receive benefit in the future from the useful advantages presented in this study.

Field measurement study of wind characteristics at different measuring positions along a bridge in a mountain valley

Wind field characteristics were investigated with a non-stationary wind speed model at a bridge in a mountain valley, where five anemometers were set along the bridge span for long-term field measurements. The mean wind characteristics, such as mean wind speed and direction, were studied with a traditional steady wind-speed model, which showed the significant influence of the terrain on the mean wind characteristics. In addition, data for certain strong-wind weather conditions were measured, and the non-stationary analysis of strong wind samples were conducted using the run test and wavelet analysis. Subsequently, the characteristics of the fluctuating wind—time-varying mean wind speed, turbulence intensity, turbulence integral scale, and power spectral density (PSD)—were compared based on the two wind speed models. The comparative results indicated that the mountain valley wind field was substantially affected by the terrain and exhibited a strong non-stationarity. However, there were certain differences between the wind field characteristics of the two wind speed models, and the recommended value was not completely consistent for the field measurements in the current specification.

Seismic cable restrainer design method to control the large-displacement response for multi-span simply supported bridges crossing fault rupture zones

Previous earthquakes have highlighted the seismic vulnerability of fault-crossing multi-span simply supported (FC-MSSS) bridges due to the large displacement of decks. Restraining devices, being of low cost and easy to install, can be a potential alternative to prevent the large displacement or falling of bridge spans for FC-MSSS bridges. However, the current restrainer design guidelines cannot provide an appropriate design method for such restraining devices in MSSS bridges accounting for the effect of faulting-induced permanent ground dislocation. To address this issue, this study aims to propose a restrainer design procedure for FC-MSSS bridges. In this proposed procedure, the restrainers are designed according to the combination of response spectrum analysis based on a linearized 2-degree-of-freedom (2-DOF) analytical model and quasi-static analysis of the bridge. A five-span simply supported bridge crossing Puqian-Qinglan fault, which is located in Puqian Bay in Hainan, China, is chosen as a case study. Two types of restrainers, i.e., elastic steel and superelastic shape memory alloy (SMA) cables, are considered for the fault-crossing bridge. Over 30 synthetic ground motions with increasing permanent ground dislocations are generated using a hybrid simulation approach. Numerical studies show that the restrainers designed by the proposed method could efficiently limit the relative displacement within a designer-specified value for the fault-crossing bridges. Using SMA cables as seismic restrainers could noticeably reduce the required length compared with elastic steel cables.

Study of Bridge Parameters on Aerodynamic Performance of Steel Arch Bridge

Aerodynamic stability is a condition required in the planning of long span bridges. Not all countries have detailed planning rules for aerodynamic stability. One of the rules that is often referred to for long span bridge planning is the Design Rules for Aerodynamic Effects on Bridges BD 49/01. This paper will discuss the effect of the value of the average wind speed per hour (Vr), mass per unit length (m) and frequency (f) on The Aerodynamic Susceptibility Parameter (Pb), critical velocity of vortex excitation (Vcr), vibration amplitude for vortex excitation (ymax), critical speed for galloping and stall flutter (Vg), and critical speed for classical flutter (Vf) refer to Design Rules for Aerodynamic Effects on Bridges BD 49/01. The value of the average wind speed per hour (Vr), mass per unit length (m) and frequency (f) will be varied for case study of Teluk Mesjid Bridge a steel arch bridgelocated in Riau Province, Sumatra Island of Indonesia.

Flutter Analysis of The Sunda Strait Suspension Bridge

Economic movements in Indonesia and the logistics and distribution systems that accompany them are highly dependent on road transportation modes. On the other hand, the islands of Sumatra and Java are the centers of concentration for the Indonesian economy where the number of people inhabiting the two islands reaches 80% of the total population of Indonesia. In order to accelerate development and increase the economic integration of Java and Sumatra, it is necessary to build the Sunda Strait Bridge. The main bridge considered incudes the long span suspension bridge. At present, the planning and construction of the long bridge including suspension bridge was greatly affected by the failure of the Taccoma Narrow Bridge on 7 November 1944. Due to the wind load, the bridge structure shook until it finally collapsed. Although the cause of the collapse was not immediately known, it is currently concluded that it was caused by a single degree of freedom torsional flutter caused by self-excited wind load. This phenomenon is classified as an aerodynamic phenomenon on long span bridges. The flutter analysis performed on the Sunda Strait Suspension Bridge using the Direct Flutter Analysis method will be presented in this paper.

Effect of span length on the trueness of an intraoral scanner. (An in-vitro study)

Abstract Statement of the problem: Digital scanning has been widely used nowadays, however its accuracy in relation to the bridge span length needs further investigations. Objective: The aim of this study was to determine the effect of span length on the trueness of an intra-oral scanner. Materials and methods: On a typodont (Nissin Dental Model, Japan) preparations for two bridge span lengths were made. One resembling missing upper second premolar representing short straight span length (SS) while the second resembling missing upper first and second premolars representing long curved span (LS). Then typodont was scanned by a laboratory scanner (InEos X5 scanner) (Sirona Dental System, Bensheim, Germany) to act as a reference model scan to compare measurements for trueness. Then for each group five scans were taken for the typodont by Medit intraoral scanner (iScan version 1.2.0.1; Medit, Seoul, Korea) to be compared with the reference scan. Then data set from the scans were transferred to STL format and then exported to exocad (exocad version 2.3 Matera exocad GmbH,Darmstadt, Germany) software to get the measurements to determine the trueness. Results: Results of this study showed that in the comparison between short and long span bridges, the long span bridge scans showed statistically significant higher root mean square (RMS) mean value (0.23±0.10 mm), lower trueness than short span bridge scans (0.06±0.04 mm). Conclusions: Long span fixed bridge had an adverse effect on the scanning accuracy. Trueness of intraoral scanner may be affected by the complexity and length of the scanning area.

Trueness of extra-oral scanner in relation to two span lengths. An in-vitro study

Statement of the problem: Extraoral scanners have been used widely nowadays however there are certain conditions that could affect their accuracy which will subsequently affect the success of the final restoration. Objective: The aim of this study was to determine the accuracy of extraoral scanner in relation to two span lengths. Materials and methods: A typodont (Nissin Dental, Kyoto Japan) was used and two bridges with different span lengths were prepared, the first one with missing upper left second premolar (short straight span (GS)) and the other with missing upper left first and second premolars (long curved span (GL)). Indentations were made on each abutment to be taken as a reference for measurements. For both groups reference scan was taken by inEos X5 extra-oral scanner. Then five physical impression was taken for each group using vinylpolysiloxane impression material (Honigum, Germany) and then poured into type IV dental stone. Casts of each group were scanned using DOF extraoral scanner (DOF Company, Korea). Measurements were made from the indentations on the reference scan and the sample scans, compared with each-other and root mean square value (RMS) was obtained to evaluate the trueness. Results: Comparison between short and long span bridges revealed that there was no statistically significant difference between trueness values of short and long span bridges. Where RMS mean for the short span was 0.0727 mm and that for the long span was 0.1069 mm. Conclusions: Different span lengths do not seem to affect the trueness of the extra-oral scanner tested.

Simple Span Bridge Loading Based on Weight in Motion Data

Over Dimension Over Load (ODOL) vehicle is claimed to be the cause of a number of fatal accidents and damage to road infrastructure in Indonesia and has become a serious issue for roads and bridges maintenance. Over loaded vehicles can result in damage to the bridge, reduced bridge capacity and can even result in collapse of the bridge. Therefore the characteristics of the actual vehicle load need to be known and compared to the bridge design load according to the bridge design code and standard. In this paper, an analysis is carried out on the actual traffic load data obtained from the measurement results using Weight in Motion (WIM) in Kaligawe, Semarang, Indonesia. Monte Carlo simulation is used to simulate the arrival of the vehicle. The results of vehicle load simulation are then applied to a simple span bridge with a span of 30, 40, 50 m. The bending moment and shear force obtained due to actual load compared to the magnitude of the bending moment and shear by applying Indonesia Bridge Loading Standard. The results show that 43 percent of vehicles are overloaded. The bending moment and shear force caused by actual load is less than the design bending moment and shear force for 30 m, 40 m and 50 m bridge span.

System-wide seismic vulnerability of aging multiple-span multiple-girder bridges in low-to-moderate seismic hazard regions

This article describes the approach, methods, and findings of a quantitative analysis of the seismic vulnerability in low-to-moderate seismic hazard regions of the Central and Eastern United States for system-wide assessment of typical multiple span bridges built in the 1950s through the 1960s. There is no national database on the status of seismic vulnerability of bridges, and thus no means to estimate the system-wide damage and retrofit costs for bridges. The study involved 380 nonlinear analyses using actual time-history records matched to four representative low-to-medium hazard target spectra corresponding with peak ground accelerations from approximately 0.06 to 0.3 g. Ground motions were obtained from soft and stiff site seismic classification locations and applied to models of four typical multiple-girder with concrete bent bridges. Multiple-girder bridges are the largest single category, comprising 55% of all multiple span bridges in the United States. Aging and deterioration effects were accounted for using reduced cross-sections representing fully spalled conditions and compared with pristine condition results. The research results indicate that there is an overall low likelihood of significant seismic damage to these typical bridges in such regions, with the caveat that certain bridge features such as more extensive deterioration, large skews, and varied bent heights require bridge-specific analysis. The analysis also excludes potential damage resulting from liquefaction, flow-spreading, or abutment slumping due to weak foundation or abutment soils.

Seismic response of CRTS II ballastless track-bridge system considering the damage of track structure.

Based on the 16-32 m simply-supported beam bridge on Shanghai-Kunming high-speed railway, a collision model of CRTS II track system was established. The model considered the longitudinal, horizontal as well as vertical nonlinear constraints among structural layers, and the Kelvin element was used to simulate the pounding effect of the gaps. The seismic response of the CRTS II track system was firstly analyzed and then the influences of different cases of damaged track plate, base plate, and mortar layer were discussed. The study revealed that: (1) The rail, track plate, and base plate all bear large longitudinal force and their stress envelope curves are all anti-symmetric. (2) The broken track plates result in a sharp decrease in track plate stress and an extreme increase in rail stress and base plate stress near the gap. The broken base plates result in a sharp decrease in base plate stress and an extreme increase in rail stress and track plate stress near the gap. (3) Both the pounding frequency and pounding force between broken slabs are relatively large and will decrease after some time. (4) The broken slabs near ends of the first bridge span greatly increase the pounding force of stoppers close to the abutment. (5) The gap width has a huge influence on the pounding force and times of stoppers and gaps. (6) The debonding of mortar layer has a great influence on the vertical displacement of rail, track plate, and the base plate.

Seismic vulnerability assessment of masonry arch bridges

A seismic assessment study of two historical masonry arch bridges, with different geometries and spans, is presented. The seismicity of the two locations was analyzed in order to define the seismic action to be applied. Artificial ground motion records were generated accordingly, and real ground motions were also used. The two numerical models were created with a 3D discrete element code. The accuracy of the deformability of the block models was verified by comparison with a finite element model. In situ measurements of the natural frequencies were available for one of the bridges, providing further means for model calibration. Time domain dynamic analyses were performed with each set of ground motions, allowing an evaluation of damage and failure modes under seismic action. The shorter span bridge was found to withstand the regulatory records with minimum damage. In contrast, the longer span bridge displayed a significant vulnerability to earthquake action. The study shows that rigid block models have the ability to represent effectively the dynamic elastic response of the bridges and can be calibrated by ambient vibration measurements. Furthermore, the discrete element models provide a powerful tool to investigate the nonlinear dynamic response and failure of these structures, which has to be based on a comprehensive set of dynamic records.

Using Bayesian networks to estimate bridge characteristics in early road designs

When deciding where to build new roads, it would be useful to obtain quickly and reliably an idea of the necessary characteristics of any potential bridges, using limited information and without considerable effort, as there is a considerable amount of information on built bridges in a standardised form, and there are robust algorithms for analysing these data. This study presents a methodology for estimating the likely bridge characteristics using the information available in a bridge database and Bayesian networks. The methodology is demonstrated by estimating the bridge characteristics of 1793 bridge records using nine situational characteristics – for example, the cross-section of the bridge superstructure and number of bridge spans. It is concluded that the methodology is a useful tool when estimating the characteristics of new bridges using only situational information. Compared with naïve-search databases queries, the prediction capability of all networks developed using the proposed methodology showed an estimated accuracy above 86.5%, which is considerably higher than that found when the methodology was not used – that is, 66.5%. Additionally, it is shown that Bayesian networks based on expert experience can obtain results similar to, and in many cases even better than, those of Bayesian networks based solely on learning algorithms.

Structural form and experimental research of truss arch bridge with multi-point elastic constraints

With the increase of the arch bridge span, the mechanical properties of arch bridges will decrease rapidly. In order to solve this problem, triangular net is set between the arch rib and girder to form a kind of truss arch bridge in which arch rib acts as top chord, girder acts as lower chord, triangular net acts as web member, and hangers provide elastic restrains at several points. The triangle stability of the truss can improve linear stiffness of arch rib and girder, which will thus improve the mechanical properties of arch bridges. A test bridge with a span of 50 m was built to prove the superiority of the truss arch bridge with multi-point elastic constraints (MTAB). Structural stresses and displacements were obtained through dead load experiments, and the mechanical properties of the structure were calculated through the finite element (FE) software. It is turned out that, compared with the conventional through arch bridge (CTAB), the mechanical performance of the MTAB is greatly improved. The test values of structural stresses and displacements match calculation values well. Moreover, with the same steel consumption, the more layers of the triangular net, the better the mechanical properties of the structure.

ANALYSIS OF THE CAUSES OF ACCIDENTAL DESTRUCTION OF THE BRIDGE THROUGH R. CHORTOMLYK

The information on emergency deterioration of the bridge span over the River Chortomlyk is presented. The analysis of the causes of this deteriortion is stated.

An indirect bridge frequency identification method using dynamic responses of high-speed railway vehicles

The identification of bridge frequencies using dynamic responses of moving vehicles has been studied by many researchers, however, most of them assume that the vehicle moves at a relatively low speed. In the application of high-speed railway bridges, the bridge span is typically short and the train always moves at a very high speed, which implies that the duration of the vehicle traveling on the bridge is very short and the signal recorded from the vehicle is not long enough for signal processing to extract the bridge frequency. The present study proposes a new method to identify the bridge frequency from vehicles moving at a high speed by combining the responses of multiple vehicles. The theoretical analysis is conducted using the simple vehicle-bridge interaction (VBI) model. By subtracting the acceleration responses of adjacent vehicles at the same position on the bridge, the residual vehicle responses were obtained and combined, which eliminated the additional driving frequencies and avoided its interference on the bridge frequency identification. Numerical simulations are then conducted to verify the proposed method, which shows that by combining the acceleration of several vehicles to extend the overall duration of the signal, the frequency resolution can be improved and the bridge frequency can be successfully identified using vehicles travelling at a high speed. The influence of track irregularity, vehicle speed, bridge stiffness, and bridge damping on the identification results has also been studied. In addition, a multi-degree-of-freedom vehicle model is used to further verify the proposed method.