Prestressing force increment of two-span steel girder

1991 ◽  
Vol 18 (2) ◽  
pp. 163-170 ◽  
Author(s):  
M. S. Troitsky ◽  
Z. A. Zielinski ◽  
N. F. Rabbani
Keyword(s):  
Virtual Work ◽  
Bending Moment ◽  
High Strength ◽  
Bridge Engineering ◽  
Advanced Technology ◽  
Steel Girder ◽  
Girder Bridges ◽  
Prestressing Force ◽  
Negative Bending ◽  
Existing Bridges

The economic advantages and the advanced technology of prestressed steel bridges has opened new opportunities in bridge engineering. The girder bridges prestressed by cables have been recognized as a technique for the design of new bridges as well as the rehabilitation and increasing the load-bearing capacity of the existing bridges. However, the prestressing of steel girders introduces new problems which require special attention and studies. The objective of this paper is to analyze the influence of the prestressing force increment and the induced negative bending moment in two-span steel girder bridges prestressed by external tendons (cables of high strength steel). The proposed analysis is based on the flexibility method. The deformations are calculated by the virtual work method. The analysis is limited to elastic stage only. The equations for calculating the prestressing force increment and the bending moment at the middle support are derived. Numerical examples are solved and the results are compared with those of similar non-prestressed girders. The influence lines are prepared and evaluated for a continuous girder of two equal spans of 60 m in length each. Key words: bridges, post-tensioned steel, force increment, analysis, influence line.

Experimental study on partial-combination method in continuous composite girder

2021 ◽  
Author(s):  
Hang Su ◽  
Qingtian Su ◽  
Wensheng Yu ◽  
Yunjin Wang ◽  
Minghui Zeng
Keyword(s):  
Concrete Slab ◽  
Bending Moment ◽  
Combination Method ◽  
Steel Girder ◽  
Advantages And Disadvantages ◽  
Girder Bridges ◽  
Composite Girder ◽  
Rubber Sleeve ◽  
Negative Bending ◽  
Composite Girders

<p>Cracking of concrete slab in the negative bending moment region of continuous composite girders is a key problem which needs to be solved in the design of continuous composite girder bridges. The main reason of concrete cracking in the negative bending moment region of continuous composite girder is tensile stress under the effects of temperature and load in the portion of integration. The paper gives the method of partial-combination to connect steel girder with concrete slab, that is, a rubber sleeve is placed on the stud of the negative bending moment region to increase the slip between the concrete slab and the steel girder at the joint. Two specimens of negative bending moment region are designed to observe the mechanical properties in the negative bending moment region of composite girders when using the method of partial-combination. The advantages and disadvantages of the partial-combination method are analysed.</p>

scholarly journals Investigation of Traffic Loading Effects for Different Codes on Medium- and Small-Span Girder Bridges in China

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qingfei Gao ◽  
Biao Wu ◽  
Jun Li ◽  
Kemeng Cui ◽  
Chuang Xu
Keyword(s):  
Bridge Engineering ◽  
Traffic Load ◽  
Bending Moments ◽  
Original Design ◽  
Traffic Loading ◽  
Simply Supported ◽  
Girder Bridges ◽  
Loading Effects ◽  
Existing Bridges ◽  
Structure Evaluation

With increasing traffic volume, the traffic load grade given by design codes has gradually increased. For new bridges, there is no problem, and the traffic load can be met through the requirements of the new code. However, for existing bridges, there is a lack of uniform standards on whether they can continue to be used. It is not clear whether these bridges will be judged according to the new code or the original design code. The traffic loading effects of different codes on medium- and small-span girder bridges in China are investigated in this study. Three codes are introduced: JTJ 021-89, JTG D60-2004, and JTG D60-2015. Simply supported girder bridges and continuous girder bridges are discussed. The traffic loading effects calculated based on JTG D60-2015 are significantly larger than those calculated based on JTJ 021-89. For simply supported girder bridges, most of the differences range from 20% to 40%, and the maximum value is almost larger than 60%. For continuous girder bridges, most of the differences in the positive bending moments are concentrated in the 20%∼40% range, while the differences in the negative bending moments range from 10% to 20%. Therefore, the differences in traffic loading effects calculated based on various codes cannot be ignored in actual bridge engineering. The conclusion in this study can provide a basis for bridge structure evaluation and life prediction.

scholarly journals Mathematical Modeling of Linear Static and Dynamic Analysis for Pier Height Effect on the Structural Performance of Bridges Structures

2021 ◽  
Vol 8 (4) ◽  
pp. 617-625
Author(s):  
Ali Fadhil Naser ◽  
Hussam Ali Mohammed ◽  
Ayad Ali Mohammed
Keyword(s):  
Time History ◽  
Bending Moment ◽  
High Strength ◽  
Response Spectra ◽  
Structural Performance ◽  
Static And Dynamic Analysis ◽  
Compressive Stresses ◽  
History Analysis ◽  
Negative Bending ◽  
Dynamic Frequency

The results of linear static analysis explained that the increasing of pier heights was leaded to rise the values of positive bending moment, tensile stresses, and downward vertical deflection. Whereas the compressive stresses and negative bending moment were decreased, indicating that the structural performance of bridge structure representing by stiffness, bearing capacity of structural members, and elasticity will decrease and the bridges structures will be damaged. Therefore, the bridges structures need safe design when using tall piers by adopting high quality materials such as high strength concrete, more steel reinforcement, more prestressed tendons, and increasing of cross section dimensions of girders and piers. The results of modal analysis show that the un-loaded dynamic frequency for three types of bridges models were decreased when the pier heights were increased, indicating that the stiffness of bridges structure was became low with higher pier height. According to response spectra and time history analysis results, the loaded dynamic frequency (vibration state) and dynamic displacement were increased when the pier heights were increased, showing that the bridge of structure will suffer from high vibration when the pier height was high. It can be concluded that from this study, the piers heights have significant effects on the static and dynamic structural performance of bridges structures under traffic loads.

Seismic Performance Research of Steel Girder Bridge with Isolation Bearings and Restrainer Cables

2013 ◽  
Vol 353-356 ◽  
pp. 2000-2003
Author(s):  
Peng Zhang ◽  
Cui Ping Pang ◽  
Min Yuan ◽  
Wan Wen Wang
Keyword(s):  
Seismic Performance ◽  
Seismic Isolation ◽  
Steel Girder ◽  
Girder Bridges ◽  
Steel Girder Bridges ◽  
Lead Rubber Bearings ◽  
Steel Girder Bridge ◽  
Girder Bridge ◽  
Rubber Bearings ◽  
Existing Bridges

The seismic performance of multi-span simply supported steel-girder bridges with sliding and high rocker steel bearings is poor during earthquakes. During the past 20 years, seismic isolation has emerged as one of the most promising strategy for improving the seismic performance of existing bridges. In this study elastomeric bearings, lead-rubber bearings, and cable restrainers are attempted to modify the seismic response of bridges, and theirs effects are analyzed and compared.

Numerical analyses of joint with steel endplates, headed stud anchors and concrete cross-beam in continuous steel-concrete composite girder bridges

2021 ◽  
Author(s):  
Bruno Briseghella ◽  
Junping He ◽  
Junqing Xue ◽  
Zordan Tobia
Keyword(s):  
Concrete Slab ◽  
Bending Moment ◽  
Element Model ◽  
Reinforcement Ratio ◽  
Continuous Steel ◽  
Moment Capacity ◽  
Girder Bridges ◽  
Negative Bending ◽  
Headed Stud ◽  
Parametric Analyses

<p>Short and medium span continuous steel-concrete composite (SCC) girder bridges are becoming more and more popular. The problems caused by the negative bending moment in the continuous SCC girders cannot be ignored. In order to investigate the performances of the continuous joints between adjacent SCC girders, consist of steel endplates and headed shear stud connected to concrete cross-beam, the finite element model was built by using ABAQUS software, of which the accuracy was verified by experimental results. The parametric analyses were carried out to investigate the influences of the strength and reinforcement ratio of the concrete slabs in SCC girders, and the diameters of the horizontal headed shear studs on the performances of the joints. The ultimate moment capacity of the joint increases with the increase in the strength and reinforcement ratio of concrete slab and the diameters of the horizontal headed shear studs.</p>

Evaluation of the Remaining Prestress Force and Center Negative Bending Moment in Crossties Removed From Track After 25 Years of Service

2019 ◽  
Author(s):  
James D. Scott ◽  
Robert J. Peterman ◽  
Aaron A. Robertson ◽  
B. Terry Beck ◽  
Kyle A. Riding
Keyword(s):  
Bending Moment ◽  
Test Method ◽  
Bending Test ◽  
Direct Tension ◽  
Longitudinal Splitting ◽  
Prestressing Steel ◽  
Prestressing Force ◽  
Four Point Bending ◽  
Negative Bending

Extensive research is currently being conducted by the team to understand the prestressing steel and concrete properties that cause high bonding stresses and lead to longitudinal splitting cracks, and how to mitigate this failure in future designs. One parameter of interest that affects the bonding stress is the amount of prestressing force in a crosstie. To help quantify the amount of prestress force necessary to provide a durable long-term crosstie, a study on existing crossties that have performed well in track for over 25 years was conducted to evaluate the center negative bending moment, and determine the remaining prestress force for each tie. The remaining prestress force in each tie was determined using a new proposed method in which ties are loaded in direct tension. The new test method was also conducted on new ties instrumented with vibrating wire strain gages to verify the method. The testing results reveal that a majority of the existing ties evaluated have a remaining prestress force in the range of 84–95 kips. These forces are significantly lower than the remaining prestress force after losses of newer tie designs. This can be seen when comparing the tension test results of the existing ties with the results of the new ties. Ties were loaded upside-down in four-point bending to determine their center negative cracking moments. The test setup and procedure used closely resembles the center negative bending moment test outlined in AREMA 30, with minor variations. For each different tie design in the study, the center negative design moment was calculated following the AREMA 30 procedure, and compared to the experimental cracking moments. Of the seven different existing tie designs investigated, four would meet the requirements of the current AREMA 30 center negative bending test.

Testing of composite girders with coiled spring pin shear connectors

2021 ◽  
Author(s):  
Robert Hällmark ◽  
Rasoul Nilforoush ◽  
Victor Vestman ◽  
Peter Collin
Keyword(s):  
Composite Structures ◽  
Bending Moment ◽  
Moment Capacity ◽  
Shear Connectors ◽  
Shear Connection ◽  
Girder Bridges ◽  
Coiled Spring ◽  
Cost Efficient ◽  
Structural Parts ◽  
Existing Bridges

<p>Today, steel girder bridges with concrete deck slabs are generally constructed as steel-concrete composite structures, to utilize the material and the structural parts in an efficient way. However, many existing bridges constructed before the early 1980´s were designed without shear connectors at the steel-concrete interface. With increasing traffics loads and higher amount of load cycles, there is sometimes a need to strengthen these bridges. One way to increase the bending moment capacity is to create composite action by post-installation of shear connectors. The authors have studied the concept of strengthening by post-installed shear connectors, with a focus on a connector called coiled spring pin. This paper presents the results from the first beam tests performed with this kind of shear connector. In line with the previous push-out tests, the test results indicate a very ductile shear connection, with a potential to be a material- and cost-efficient strengthening alternative.</p>

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