Curved Steel Box Girder Bridges Research Articles

Influence of ground motion parameters on seismic response of a large-longitudinal-slope and small-radius curved girder bridge.

The mechanical performance of curved bridges under the action of an earthquake is complex. To obtain the influence of seismic parameters on the seismic response of curved girder bridges, this paper relies on a large slope small-radius curved steel box girder bridge (LSCGB) and selects seismic wave incidence angle, vertical component of ground motion, and site category as seismic parameters to carry out nonlinear time history analysis. Based on the analysis results of the case bridge, it is shown that the torsional vibration of the first 10 modes of LSCGB is significant, the modes are dispersed, and the contribution of high-order modes of vibration cannot be ignored. The most unfavorable seismic wave incidence angle is in the direction of 45°∼60° counterclockwise Angle from the central connection line of Pier No. 1 and Pier No. 4 of the bridge. The seismic response of the curved bridge components increases with the vertical seismic intensity, and the influence on displacement responses is more significant. The basic vibration period of curved girder bridges built on soft soil sites is extended by approximately 18.23%, and the seismic response of key components increases with the softening of the site soil. Therefore, when analyzing the seismic response of LSCGBs, the influence of vertical component of ground motion and site category should not be ignored.

Coordinate Monitoring Technology in the Process of Incremental Launching Construction of Curved Steel Box Girder Bridge

Based on the steel box girder curve incremental launching project of SW ramp bridge in Harbin East Third Ring Road, the geometric alignment and structural internal force of the steel box girder during the incremental launching process were monitored in the whole process. The curve incremental launching coordinate position control method was adopted, and the relevant parameters were modified according to the site construction situation and the initial stress conditions of the girders, and the corrected theoretical value was used as the control and evaluation basis of the monitoring value. The results showed that the original theoretical deflection value was −33.10 mm, the modified theoretical deflection value was −64.10 mm, and the actual monitoring value was −53.20 mm. The modified theoretical value agreed well with the monitoring value, and the error rate between the monitoring value and the theoretical value under each working condition was −17.82%∼14.48%. The geometric alignment and internal force of the steel box girder met the monitoring requirements, ensuring that the steel box girder can meet the design requirements under various working conditions.

Behaviour and Analysis of Horizontally Curved Steel Box-Girder Bridges

Various theories and analytical formulations were implemented and exploited in the 1980s and 1990s for the design of bridge beams or decks curved in the horizontal plane and subjected to out-of-plane loads. Nowadays, the Finite Element Method (FEM) is a valid tool for the analysis of structures with complex geometries and, therefore, the development of sophisticated analytical formulations is not needed anymore. However, they are still useful for the validation of FE models. This paper presents the case study of an existing viaduct built in North Italy, aiming to compare analytical approaches and numerical modelling. The bridge is characterized by an axis curved in two directions and a rectilinear segment. The global analysis of the viaduct is carried out with special attention to the attributes that cause torque action and bending moment. The theoretical developments focus on a deeper understanding of the torsional response under different constraint and loading conditions and aspire to raise awareness of the mutual interaction of flexural and torsional behaviour, that are always present in these complex curved systems. The examination of the case study is also obtained by comparing the response of isostatic and hyperstatic curvilinear steel box-girders.

Analysis on the Stability of Top Pushing Construction of Curved Steel Box Beam of a Cross-sea Bridge

The curve steel box girder has the risk of instability in the jacking construction, especially in the case of big waves on the sea surface. It is very important to analyze the stress of the structure during the jacking construction. According to the Midas Civil finite element model, a bridge span is arranged as (49+60+49) m according to various unfavorable loads. The stability of the curved steel box girder bridge during jacking construction is analyzed, and the site construction is controlled according to the calculation results.

Numerical performance assessment of Tuned Mass Dampers tomitigate traffic-induced vibrations of a steel box-girder bridge

In this paper, the effects of Tuned Mass dampers (TMDs) on the reduction of the vertical vibrations of a real horizontally curved steel box-girder bridge due to different traffic loads are numerically investigated. The performance of TMDs to reduce the bridge vibrations can be affected by the parameters such as dynamic characteristics of TMDs, the location of TMDs, the speed and weight of vehicles. In the first part of this study, the effects of mass ratio, damping percentage, frequency ratio, and location of TMDs on the performance of TMDs to decrease vertical vibrations of different sections of bridge deck are evaluated. In the second part, the performance of TMD is investigated for different speeds and weights of traffic loads. Results show that the mass ratio of TMDs is the more effective parameter in reducing imposed vertical vibration in comparison with the damping ratio. Furthermore, it is found that TMD is very sensitive to its tuned frequency, i.e., with a little deviation from a suitable frequency, the expected performance of TMD significantly decreased. TMDs have a positive and considerable performance at certain vehicle speeds and this performance declines when the weight of traffic loads is increased. Besides, the results reveal that the highest impact of TMD on the reduction of the vertical vibrations is when free vibrations occur for the bridge deck. In that case, maximum reductions of 24% and 59% are reported in the vertical acceleration of the bridge deck for the forced and free vibration amplitudes, respectively. The maximum reduction of 13% is also obtained for the maximum displacement of the bridge deck. The results are mainly related to the resonance condition.

Effect of Different Constraint Systems on the Seismic Response of Double-Deck Curved Girder Bridges

Double-deck curved girder bridges can achieve large climb in a short distance, and their seismic response differs from that of regular bridges due to their special structural form. The constraint system of bridges, which consists of bearings and shear keys, has a key influence on the seismic response of the bridge structure. Accordingly, this research aims to develop a reasonable constraint system for double-deck curved girder bridges. A finite element simulation of a double-layer curved steel box girder bridge is also conducted to compare some indexes, which are the displacement of bearings with the curvature of the pier section. The shear bolt is selected as the limit device to study the influence of shear bolts and different bearings on the seismic response of the double-deck curved girder bridge structure. Under the influence of ground motion, the displacement of the upper bearings of double-layer curved girder bridges is generally larger than that of the lower bearings. The double-layer constraint system makes the section curvature and ductility in the middle of the pier smaller than that at the top and bottom of the pier. The spherical steel bearings have a small displacement, whereas the pier has a large internal force. After setting the shear bolts, the displacement of the spherical steel bearings decreases, whereas the damage to bridge piers does not show obvious changes. When the displacement of elastomeric pad bearings increases, sliding occurs under a low ground motion intensity, thereby reducing the degree of damage to the bridge pier. Moreover, the application of shear bolts limits the displacement of bearings and subsequently increases the seismic force being transmitted to the pier whose damage is the most serious. However, the displacement of pot bearings is relatively small, and the displacements of the upper and lower layers are close. In addition, the seismic inertial force of the superstructure is relatively uniform, thereby protecting the piers to a certain extent. After setting the shear bolts, the deformation falls within an allowable range, whereas the damage to the bridge piers slightly increases. Therefore, combining pot bearings with shear bolts creates a reasonable constraint system for double-deck curved girder bridges.

Research on Shear Lag Effect of Three-span Continuous Curved Steel Box Girder Bridge

The normal stress of box-section beam under symmetrical load is the non-uniform characteristic called shear lag effect. Based on actual engineering project, the plate-beam finite element method is used to study the shear lag effect of the three-span continuous-curve steel box-girder bridge under the variety conditions of the curve radius, and the width span ratio, and the distribution of the shear lag effect in the longitudinal and horizontal direction under the symmetrical load are summarized in this paper, providing references for design of steel box-girder bridge. The results show that the shear lags of steel box girders are all positive shear lags under symmetrical loads. Under the conditions of three parameters, the curve radius and the width-span ratio have a great influence on the shear lag effect of steel box girders, and the high-span ratio change has no obvious effect on the shear lag effect, and the shear lag effect of bottom plate is far less severe than the top plate.

Thermal Effects on Curved Steel Box Girder Bridges and Their Countermeasures

AbstractOwing to its light self-weight, low heat capacity and large thermal expansion coefficient, the application of the curved steel box girder bridge with small and medium spans has gained popularity for the construction of urban infrastructure. However, sun exposure could easily increase the maximum temperature difference at the bottom of steel box beam by 25°C. With the effect of nonuniform temperature field and overloaded vehicles, the edge inside the curved steel box girder bridge may be separated from the remaining structure, resulting in overturning. Thus, more attention needs to be paid in order to prevent the separation. In this paper, an overturning resistance analysis of a three-span curved steel box girder bridge located in Hangzhou, China was performed. A model was proposed based on the measurement of temperature field to the steel box girder. The separating displacement due to temperature variations was predicted and verified by the measurement results. As a result, changes in supporting r...

Load Test and Model Calibration of a Horizontally Curved Steel Box-Girder Bridge

In this paper, full scale load test of a horizontally curved steel box-girder bridge is carried out in order to detect structural defects, which reportedly result in unwanted vibrations in nearby buildings. The bridge is tested under the passage of six heavy vehicles at different speeds, so as to determine its static and dynamic responses. A total number of one hundred and two (102) sensors are used to measure the displacements, strains, and accelerations of different points of the bridge. It is observed that the bridge vibrates at a fundamental frequency of 2.6 Hz intensively and the first mode of vibration is torsional instead of flexural. The dominant frequency of vibration of the nearby buildings is computed to be approximately 2.5Hz using rational formulas. Thus, nearness of the fundamental frequency of the bridge to those of the adjacent buildings may be causing resonance phenomenon. However, in static load tests, low ranges of strain and displacement illustrated adequate structural capacity and appropriate safety under static loads. Numerical models are created using ANSYS and SAP2000 software products, so as to design the loading test and calibrate the finite element models. The connections of the transversal elements to the girders, transversal element spacing, and changes of the stiffness values of the slabs were found to be the most influential issues in the finite elements calibration process. Finally, considering the total damage of all members, the final health score of the bridge was evaluated as 89% indicating that the bridge is in a very good situation.

Effect of Small Radius on the Performance of Curved Steel Box Girder Bridge

According to the design of a three--span 38m+6om+38m bridge of cambered steel box beams, it is mainly presented that the construction methods of an urban viaduct of cambered steel box beams, its paved floor and treatment of shear lag effect., through the six series of 20 specimens calculation and analysis, simulation different local structures curved steel box girder bridges reflect more accurately the role of various factors in the mechanical behavior. This in-depth analysis of the different local structures in space curved steel box girder bridge performance, for guiding the engineering design has a certain reference value for further study curved steel linear and nonlinear mechanical properties and stability lay a good foundation.

The Effect of Local Structure on the Performance of Curved Steel Box Girder Bridge

This paper considers material nonlinearity and geometric nonlinearity,study in-depth the force performance using the finite element method for space curved steel box girder bridge, through the six series of 20 specimens calculation and analysis, simulation different local structures curved steel box girder bridges reflect more accurately the role of various factors in the mechanical behavior. This in-depth analysis of the different local structures in space curved steel box girder bridge performance, for guiding the engineering design has a certain reference value for further study curved steel linear and nonlinear mechanical properties and stability lay a good foundation.

Application of Local Reference-Free Damage Detection Techniques to In Situ Bridges

There are increasing demands to apply structural health monitoring (SHM) techniques to bridge structures. To meet these demands, the authors' group has developed a suite of local SHM techniques that can detect particular types of damage without using baseline data obtained from the pristine condition of a structure. They are coined as reference-free damage detection techniques. The main advantage of the reference-free techniques is that they can provide improved damage diagnosis even when the system being monitored is exposed to ambient variations such as external load and temperature changes. Since the reference-free techniques do not rely on a direct comparison with previously obtained baseline data, they are less vulnerable to false alarms due to undesirable variations which in-site structures are frequently subjected to. In this study, the applicability of two specific reference-free techniques to real bridge structures and associated implementation issues are examined through field tests of a decommissioned curved steel box girder bridge and an in-service single-span steel girder bridge in Korea. The authors' monitoring efforts are focused on detection of cracking in critical steel members with additional structural features such as stiffeners and diaphragms. External loading effects on the reference-free techniques are investigated through static and dynamic loading tests using a 35-t dump truck. Furthermore, daily/seasonal temperature variations are observed over a 1-year period. The test results confirm that the reference-free techniques successfully identify cracks on the test bridges even under varying external loading and temperature conditions. In addition, the long-term durability issues of piezoelectric transducers (PZTs) are addressed, and an enhanced PZT design has been proposed to improve the PZT durability.

Mechanical Analysis of Deck Pavement of Curved Continuous Steel Box Girder

The geometric structure of steel deck plates is complex. So it is difficult to get precise results in the mechanics calculation of deck pavement with traditional methods. This paper adopts the finite element method for the mechanics analysis of the composite guss asphalt surfacing layer of curved steel box girder bridges. By taking the orthotropic steel deck and the pavement as a whole, a reasonable finite element model is established and optimized for the mechanical study of steel deck pavement. This model can be used to study the stress and deformation features of the surfacing layer. According to the common diseases in steel deck pavements and the effect of the overload and the horizontal load in braking to the pavement, this paper puts forward the comprehensive control indicators for pavement failures.

Structure Identification and Load Capacity Rating of Veteran's Memorial Curved Steel Box Girder Bridge

Veteran's Memorial Bridge is a curved steel box girder bridge located in Tallahassee, Florida. A structural system identification procedure through field test and analysis was developed for the bridge. A bridge capacity rating is included. The tests include a bending test, a shear test, and a structural system test. Test and analytical results indicate (a) nearly all concrete areas of the bridge deck and barriers are composite with the steel box girders and effectively resist both bending and shear forces, (b) the shear capacity at the end abutment is much higher than that predicted by current AASHTO Guide Specifications for Horizontally Curved Highway Bridges, and (c) the bridge behaves predictably. On the basis of test and theoretical results, a reliable analytic model was developed. Load ratings for 13 types of trucks permitted in Florida were performed according to the identified analytical model. Rating results show that the operating rating loads evaluated on the basis of the identified model are greater by approximately 43% than those obtained on the basis of current AASHTO guide specifications. The operating rating factor for the HS20–44 vehicle based on the identified model is 38% greater than that obtained in 1997. The rating procedures presented are instructive and can be used in bridge load-rating activities.

A study on thermal behaviour of curved steel box girder bridges considering solar radiation

Solar radiation induces non-uniform temperature distribution in the bridge structure depending on the shape of the structure and shadows cast on it. Especially in the case of curved steel box girder bridges, non-uniform temperature distribution caused by solar radiation may lead to unusual load effects enough to damage the support or even topple the whole curved bridge structure if not designed properly. At present, it is very difficult to design bridges in relation to solar radiation because it is not known exactly how varying temperature distribution affects bridges; at least not specific enough for adoption in design. Standard regulations related to this matter are likewise not complete. In this study, the thermal behavior of curved steel box girder bridges is analyzed while taking the solar radiation effect into consideration. For the analysis, a method of predicting the 3-dimensional temperature distribution of curved bridges is used. It uses a theoretical solar radiation energy equation together with a commercial FEM program. The behavior of the curved steel box girder bridges is examined using the developed method, while taking into consideration the diverse range of bridge azimuth angles and radii. This study also provides reference data for the thermal design of curved steel box girder bridges under solar radiation, which can be used to develop design guidelines.

Impact Factors of Curved Steel Multibox Girder Bridges

A method for estimating dynamic loading of steel multibox girder bridges caused by moving vehicles, based on an extensive parameter analysis of 216 multibox girder bridges, was developed. The curved multibox girder bridge is modeled as a curved grillage system. The analytical vehicle, simulated as a nonlinear vehicle model with 11 degrees of freedom, is the HL-93 truck, as described in the AASHTO specifications. Truck parameters include the body, suspensions, and tires. The bridge deck surface is assumed to be classed as good and is simulated with a stochastic process (power spectral density function). The bridge–vehicle interaction model is validated by field test results from two curved steel box bridges. The analytical results show that the torsion impact factors for curved box girder bridges can be relatively high, whereas moment, shear, and deflection impact factors are normally less than those of corresponding straight box girder bridges because of restricted vehicle speed on curved bridges. The proposed simplified impact equations are appropriate for the design of curved steel box girder bridges.

Structural health monitoring of bridges in the State of Connecticut

A joint effort between the Connecticut Department of Transportation and the University of Connecticut has been underway for more than 20 years to utilize various structural monitoring approaches to assess different bridges in Connecticut. This has been done to determine the performance of existing bridges, refine techniques needed to evaluate different bridge components, and develop approaches that can be used to provide a continuous status of a bridge’s structural integrity. This paper briefly introduces the background of these studies, with emphasis on recent research and the development of structural health monitoring concepts. This paper presents the results from three different bridge types: a post-tensioned curved concrete box girder bridge, a curved steel box-girder bridge, and a steel multi-girder bridge. The structural health monitoring approaches to be discussed have been successfully tested using field data collected during multi-year monitoring periods, and are based on vibrations, rotations and strains. The goal has been to develop cost-effective strategies to provide critical information needed to manage the State of Connecticut’s bridge infrastructure.

Dynamic Loading of Curved Steel Box Girder Bridges due to Moving Vehicles

This paper presents a simplified method for determining the dynamic loading of curved steel box girder bridges due to vehicles moving across rough bridge decks. The curved single box girder bridges are divided into a number of thin-walled beam elements. The curved multi-box girder bridges are modeled as a curved grillage system. The analytical vehicle, simulated as a non-linear vehicle model with 11 degrees of freedom, is the HL-93 truck as described in the American Association of State Highway and Transportation Officials (AASHTO) specifications. Truck parameters include the body, suspensions, and tires. The bridge deck surface is simulated using a stochastic process (power spectral density function). The dynamic loading of 28 three-span continuous single box girder bridges and 216 three-span continuous multi-box girder bridges, with span lengths ranging from 22,83–30,48–22,86 m to 64,01–85,34–60,01 m is analyzed. The analytical results show that the torsion impact factors for curved box girder bridges can be relatively high, while moment, shear, and deflection impact factors are normally less than those of corresponding straight box girder bridges due to restricted vehicle speed on curved bridges. The proposed simplified impact equations are appropriate for the design of both curved single box and multi-box girder bridges.

Full-Scale Test and Analysis of a Curved Steel-Box Girder Bridge

Since the first edition of the AASHTO Guide Specifications for Horizontally Curved Steel Girder Highway Bridges was published in 1980, there have been two more editions including many revisions to the specifications. Some changes were based on valid research results and others were based on limited or uncertain research results and information. The current edition of the specifications contains provisions that may result in unreasonably conservative load capacity ratings. In this paper, the results of field tests and analyses conducted on the Veterans’ Memorial curved steel-box girder bridge are discussed. Test and analytical results show: (1) current AASHTO guide specifications regarding the first transverse stiffener spacing at the simple end support of a curved girder may be too conservative for bridge load capacity ratings; (2) current AASHTO guide specifications may greatly overestimate the dynamic loadings of curved box girder bridges with long span lengths; and (3) a plane grid finite-element model...

Parametric seismic analysis of curved steel box-girder bridges with two continuous spans

Curved steel box-girder bridges are aesthetically pleasing and functionally effective, particularly at highway interchanges with curved alignments. A parametric analytical study of the seismic behavior of this type of bridges is performed. The study