Continuous Rigid Frame Bridge Research Articles

Modified Multi-Support Response Spectrum Analysis of Structures with Multiple Supports under Incoherent Ground Excitation

This study develops a modified multi-support response spectrum (MSRS) method, in order to efficiently and accurately calculate the response of multi-support structures under incoherent ground motions. The modified MSRS method adopts three ancillary processes, constructing structural displacement vectors or constructing infinite stiffness members or increasing the degrees of freedom at structural supports. Then, the modified MSRS method is verified in a comparison with the existing MSRS method through a model of a five-span reinforced concrete continuous rigid frame bridge. Finally, the collective structural response spectrum, the structural power spectrum, and the simplified structural power spectrum are deduced from the equation of the motion taking ground motion displacements as the input, and validated through the same bridge model.

Calculation of Evolutionary Power Spectral Density of Bridge Response to Earthquakes by Convolution Summation

This paper presents a method for calculating the evolutionary power spectral density (EPSD) of the seismic response of bridges using the convolution summation. With zero initial values, a formula for the dynamic component of the response of bridges to spatially varying seismic ground motions is derived as the convolution summation, by assuming the seismic acceleration to vary linearly between two adjacent time stations. The convolution summation is used for calculating the convolution integral of the dynamic component response factor in the EPSD, in which the constant coefficients are independent of the harmonically modulated excitation. The constant coefficients are obtained by the time-history analysis using triangular unit impulse acceleration excitations. The computational cost of the EPSD depends mainly on the amount of degrees-of-freedom (DOFs) numbers of bridge supports in contact. The corresponding computational scheme is proposed, and its validity is indirectly verified with a single DOF system, by comparing the results obtained with those of the existing methods. Finally, a three-span continuous rigid-frame bridge is taken as a case study to illustrate the applicability and effectiveness of the proposed scheme.

Comparison and Selection of Bridge Type Schemes Based on AHP and Grey Correlation TOPSIS

Determination of the optimal bridge scheme is crucial in the preliminary design stage of bridge construction, and the scientific decision results directly affect the construction and implementation of the whole project. At present, the determination of bridge schemes in mountainous areas is mainly based on empirical judgment, and few theoretical methods can be adopted. Therefore, a comprehensive evaluation model was built for mountainous bridge type scheme by the basic AHP theory, grey relational analysis, and TOPSIS. The model comprehensively considered the various factors affecting the selection of bridge type from the aspects of economy, technology, and society, and 12 evaluation indexes were selected to build a comprehensive evaluation system for the bridge type scheme in mountainous areas. Weight vector of valuation indexes of bridge type was calculated by AHP to reduce the influence of human subjective factors. Then, a weighted grey correlation coefficient decision matrix was constructed by fuzzy mathematics theory and grey correlation analysis, and the relative closeness coefficient between the alternative schemes and the Grey correlation ideal solution was calculated by TOPSIS. Finally, the optimal bridge type scheme was determined based on the relative closeness coefficient. The evaluation model was used to judge three alternative bridge type schemes (A1-A3) of a highway in the mountainous area of Pu'an County, Guizhou Province. The relative closeness coefficients of continuous PC T beam bridge (A1), PC continuous rigid frame bridge (A2), and PC dwarf-tower cable-stayed bridge (A3) were respectively 0.597 7, 0.315 6, and 0.400 3, indicating the first scheme is the best optimized bridge type. Thus, the first bridge scheme was applied to actual bridge construction and achieved good economic and social values. The results show that the evaluation model provides a feasible theoretical method for the decision-making of mountain bridge type.

Geometrically Nonlinear Stability of Curved Continuous Rigid Frame Bridges with Initial High Pier Imperfections at Largest Cantilever Stage

Geometrically Nonlinear Stability of Curved Continuous Rigid Frame Bridges with Initial High Pier Imperfections at Largest Cantilever Stage

Analysis on the Time‐Varying Fragility of Offshore Concrete Bridge

For offshore bridges, the most prominent problem in the whole life cycle is that it is in an earthquake prone zone and an offshore corrosion environment at the same time. A nonlinear dynamic analysis model is set up for an offshore multispan and continuous rigid frame bridge based on the OpenSEES platform. The fragility surface of the bridge pier, bearing, bridge platform, and system are established by selecting a reasonable damage constitutive model of the material durability and a damage index analysis that studies the damage of the bridge durability to time‐varying seismic fragility of bridge components and the system of the whole life cycle in offshore environment. The results show that the durability damage will lead to a constant decline in seismic capacity of the pier and an increase of the seismic demand under earthquake action as well as the probability to reach the ultimate failure state; compared to high piers, a low pier is more vulnerable to the offshore corrosion environment; the seismic fragility of bridge platform is higher than that of simply bearing; and the influence of offshore corrosion on environment is relatively large. With the prolongation of service period, the effect of durability damage on the seismic fragility of bridge system cannot be ignored in the coastal environment and it is necessary to make a reasonable evaluation on the seismic fragility of bridge structure during the whole life period.

Seismic Fragility Analysis of Long-Span Bridge System with Durability Degradation

An offshore long-span continuous rigid-frame bridge is taken as an example to study the effect of degradation of bond-slip behavior on the seismic performance of bridges in an offshore environment during a service period. On the basis of a numerical simulation analysis using the OpenSeeS platform, the influence of durability degradation of concrete carbonization, steel corrosion, and degradation of bond-slip performance is considered collectively using incremental dynamic analysis method to examine the time-varying seismic fragility of the offshore bridge. Results show that when bond slip is considered, the exceedance probability of the bridge components and the system increases significantly, and the durability degradation caused by concrete carbonization and chloride ion erosion in the whole life cycle increases the seismic response of the bridge structure. The results of the proposed time-varying seismic fragility analysis indicate that, considering the degradation of bond-slip behavior of reinforced concrete after the durability degradation of materials, the exceedance probability of the pier, bearing, abutment, and system increases with the extension of service period and the increase in seismic strength under earthquake action. In addition, with the extension of service time, the effect of bond slip on the seismic fragility of components and system gradually decreases.

Three‐dimensional nonlinear creep and shrinkage effects of a long‐span prestressed concrete box girder bridge

To analyze the impacts of creep and shrinkage effects on the behaviors of long‐span prestressed concrete box girder bridges, a new nonlinear analysis model of creep and shrinkage effects that comprehensively considered three‐dimensional (3D) characteristics and girder damage evolution was presented. A corresponding numerical analysis method was implemented into the ABAQUS user‐supplied subroutine; this method was verified by comparing the analytical results to the classical experimental results. Finally, a continuous rigid frame bridge with a main span of 220 m was taken as an engineering example, and the analysis results and in situ measured data of long‐term deflection were compared. The results show that the 3D characteristic and the nonlinear property of creep have significant impacts on the prediction of long‐term deflection.

Calculation of Creep Effect of Extradosed Cable-stayed bridge based on Midas Civil

In order to understand the creep effect of Extradosed bridge, the paper adopted four concrete creep calculation models recommended by Chinese, European, American and Japanese specifications, Taking the first concrete Extradosed cable-stayed bridge under operation in Yunnan Province of China as an example, The effect of creep on the displacement and stress of the main beam, and the Cable Tension were calculated. The results show that as for the impact of creep effect on deflection of the main beam of the Extradosed cable-stayed bridge, the absolute value is smaller than that of the continuous rigid-frame bridge with the same span, but it has a relatively great impact on the stress and cable force. This article is proposed that as reserve of stress at the lower edge of the section in non-stayed cable segment area should be increased appropriately, and the safety coefficient of stay cables at the operating stage can be properly increased, and the value recommended by this article is 1.87

Analysis of Non-Uniform Shrinkage Effect in Box Girder Sections for Long-Span Continuous Rigid Frame Bridge

To consider the effect of non-uniform shrinkage of box girder sections on the long-term deformations of continuous rigid frame bridges, and to improve the prediction accuracy of analysis in the design phase, this paper proposes a new simulation technique for use with general-purpose finite element program. The non-uniform shrinkage effect of the box girder is transformed to an equivalent temperature gradient and then applied as external load onto the beam elements in the finite element analysis. Comparative analysis of the difference in deflections between uniform shrinkage and nonuniform shrinkage of the main girder was made for a vehicular bridge in reality using the proposed technique. The results indicate that the maximum deflection of box girder under the action of non-uniform shrinkage is much greater than that under the action of uniform shrinkage. The maximum downward deflection of the bridge girder caused by uniform shrinkage is 5.6 mm at 20 years after completion of bridge deck construction, whereas the maximum downward deflection caused by non-uniform shrinkage is 21.6 mm, which is 3.8 times larger. This study shows that the non-uniform shrinkage effect of the girder sections has a significant impact on the long-term deflection of continuous rigid frame bridge, and it can be accurately simulated by the proposed transformation technique.

Research on durability of a concrete continuous rigid frame bridge

The research on the durability of concrete structures has also become one of the most important topics for discussion at international academic institutions and conferences. This paper summarizes and reviews the current research on the durability of bridge structure of the bridge at the index relationship between state lifetime and structure durability. According to the actual situation in this paper on a continuous rigid frame bridge China of Yunnan as an example, this bridge was completed and opened to traffic during the first half of the year, a series of tests are carried out for the durability problem. It is found that all the indicators are good within six months after the bridge opened to traffic, but durability issues should be further studied in future monitoring efforts.

Seismic Response of Double Thin–Wall Continuous Rigid Frame Bridge Considering Traveling Wave Effect

A double thin-wall continuous rigid frame bridge with a span of (68 + 116 + 68)m is selected as the engineering background in this study. A full-bridge finite element model is established with the assistance of MIDAS software to analyze the seismic performance of double thin–wall continuous rigid frame bridge. The multi-support seismic excitation is applied to consider the traveling wave effect. The results show that the self-vibration period of the double-thin continuous rigid frame bridge decreases with the increase of the double-limb spacing. The seismic responses obtained by considering travelling effect tend to those obtained without considering travelling effect when the apparent velocity increases. The seismic responses of the substructure are reduced by considering the traveling wave effect, while the traveling wave effect has significant effect on the superstructure. The axial force of the girder with considering the traveling wave effect is 3 times greater than that with uniform excitation. Therefore, the preliminary design or seismic analysis of the double thin-walled structure should focus on the influence of the traveling wave effect on the superstructure.

Effect of Concrete Creep on the displacement of single tower single cable plane Extradosed Cable-stayed Bridge

Extradossed Cable-stayed Bridge is both cable-stayed Bridge and Continuous rigid frame bridge mechanics feature, Beam is the main force components, cable is supplement.This article combined with a single tower and single cable plane Extradossed cable-stayed bridge in Yunnan, use different creep calculation models and analysis deflection caused by creep effects. The results showing that deflection caused by creep effect is smaller than the same span continuous rigid frame bridge, the value is about 2cm. On the other hand the deflection is increasing with ambient humidity decreases, therefore in the dry environment the calculation model is relatively large in the pre-camber. In the choice of RC creep model is significant in the dry areas.

Construction simulation analysis of 120m continuous rigid frame bridge based on Midas Civil

In this paper, a three-dimensional finite element model of a continuous rigid frame bridge with a main span of 120m is established by the simulation and analysis of Midas Civil software. The deflection and stress of the main beam in each construction stage of continuous beam bridge are simulated and analyzed, which provides a reliable technical guarantee for the safe construction of the bridge.

Seismic Response of Long Span Continuous Rigid-Framed Steel Arch Bridge

This paper investigates seismic responses of Xinguang Bridge, a 3-span continuous rigid-frame and steel-truss arch bridge. Earthquake excitation input is a key issue for the seismic analysis. This paper uses a finite element method to study the traveling wave effect on Xinguang Bridge and its interaction with the dynamic properties of the bridge under the condition of two steps and two levels probability. The seismic response of the bridge under the coincident earthquake excitation is also analyzed. Comparisons show that the seismic response of the long-span bridge by considering the traveling wave effect is much different from that under consistent earthquake excitation. The influence of the shear wave speed on the seismic response of the long span continuous bridge is also explored and the shear wave speed is found to greatly affect the wave shape and magnitude of the time-history of the longitudinal displacement at the crown of the main arch of the bridge. It is concluded that traveling wave effect and shear wave speed of ground have significant influences on the seismic response of the long span continuous rigid-framed and steel-truss arch bridge.

Seismic Performance Analysis of Continuous Rigid Frame Bridges in Expressway under Non-linear Interactions of Soil-Piles

Taking the three-span pre-stressed concrete continuous rigid frame bridge as an engineering example, MIDAS Civil was utilized to establish a spatial finite element model and the interaction between pile foundation and the soil was simulated by equivalent soil spring. In addition to analyzing shearing force, bending moment and stress of the primary beam's characteristic section under different loads, a response spectrum method and time history analysis were adopted to conduct seismic response analysis respectively. In this case, performance of the bridge could be comprehensively evaluated. Relevant analysis results indicate that internal force of the large-span pre-stressed concrete continuous rigid frame bridge is mainly induced by gravity and pre-stress of the structure; section stresses of the primary beam satisfy the corresponding specification and structural safety can be achieved in a state of operation. Moreover, computed results obtained by the response spectrum method is more conservative than those of the time history analysis. In terms of continuous rigid frame bridge, different seismic directions should be taken into consideration during structural seismic analysis at different construction stages.

Analysis of Stress Inhomogeneous Coefficient of a Continuous Rigid Frame Bridge during Construction Stage

The box section which can meet the requirements of wider deck is widely used in the construction of continuous rigid frame bridge. However, the shearing force lag is very obvious, which causes the inhomogeneous distribution of stress in the cross section, and it may threaten the safety of the bridge structure when it is serious. Taking a continuous rigid frame bridge located in Yunnan, China as an example, this paper establishes the finite element calculation model of the bridge to analyze the stress inhomogeneity in the construction stage. The results show that the shear lag coefficient of the section is constantly changing during the dynamic process of construction, with the increase of the length of the cantilever, the shear lag coefficient gradually converges to 1; prestress is the most important factor that causes the lateral inhomogeneity of the positive stress.

Construction Stability Analysis of Curved Continuous Rigid Frame Bridges with High Piers

Taking the curved continuous rigid frame bridges (CRFBs) with high piers as research object, the construction stability of four different styles of main piers were analyzed by finite element (FE) method in three construction stages including the segment 0 stage, largest cantilever stage, and finished bridge stage. Rules governing the stabilities of bridges with various pier styles, height, and slenderness ratio were established. At different construction stages, pier type and pier height affect structural stability differently. Wind loads have little influence on structural stability at any construction stage, and accidental events influence the stability of bridges more than normal construction loads. There is a nonlinear power relationship of fixed functional type between the stability safety factor (SSF) and slenderness ratio in all four pier styles; this power relationship can be used to predict the stability of a new pier.

Study on bridge checking evaluation based on deformation-Stress data

Bridge structure plays a very important role in human traffic. The evaluation of bridge structure after a certain period of operation has always been the focus of the bridge. Based on the data collected from the health inspection system of a continuous rigid frame bridge on a highway in Yunnan, China, it is found that there is a certain linear relationship between the deformation and stress of the bridge structure. In view of a specific section of the structure, the stress value of this section can be derived according to its deformation value. The coefficient K can be calculated by comparing the estimated value to the actual measured value. According to the range of the K value, the structural state of the bridge can be evaluated to a certain extent.

贵都高速大跨径连续刚构桥——石门坎大桥长期挠度监测分析

贵都高速大跨径连续刚构桥——石门坎大桥长期挠度监测分析

Research on application of grey system theory in construction monitoring of continuous rigid frame bridge

Research on application of grey system theory in construction monitoring of continuous rigid frame bridge