PSC Girder Bridges Research Articles

RC Arch Deck Development and Performance Evaluation for Enhanced Deck Width

Due to extreme business competitions in bridge construction industries, the cost reduction became the most important issue in winning a contract bidding. The largest bridge construction cost saving can be obtained by using precasted construction method and by reducing required number of girders, columns, and decks in the bridge system. Therefore, an precasted arch deck system is proposed to widen the lateral span of the deck, which can result in reducing the number of required I-type PSC girders for construction cost saving. A usual lateral width of a flat deck is 1.5–2.0 m, but the width of arch deck is 2.5 m, an increase of 25–60%. Therefore, for a PSC girder bridge with a total width 10 m, a number of required girders needed for ordinary flat RC deck and arch deck is 5 and 4, respectively. This means that one less girder can be required, which means that 20% of girder construction cost can be achieved by using arch deck over ordinary flat deck. In this study, precasted RC arch deck is developed and manufactured to evaluate structural performance of the deck. The study results showed that arch deck has performance exceeding ordinary flat deck and can be used as alternative decks for precasted PSC I-girder bridge construction. The study results are discussed in detail in the paper.

Rotational Angle Measurement of Bridge Support Using Image Processing Techniques

Measuring a very small rotational angle accurately and dynamically is indeed a challenging issue, especially in the case of bridge support. Also, existing inclinometers do not have sufficient resolution and accuracy to measure a bridge’s rotational angle. In this study, a new measurement system was developed to provide a practical means for measuring dynamic rotational angle of a bridge support. It features high resolution and accuracy compared with the available systems on the market. By the combinational use of a laser pointer and a vision-based displacement measurement system, the measurement accuracy was significantly increased. The accuracy and applicability were investigated through laboratory tests. From the laboratory tests, it has been found that the developed system can be applicable to bridge support with very small rotational angle. The effectiveness of the developed system was verified through field tests on real bridges. From the full-scale implementation on two PSC girder bridges, it is observed that the proposed system can measure the rotational angle with a high accuracy and reliability.

Experimental Evaluation of Prestress Force in Tendons for Prestressed Concrete Girders using Sensors

The prestressing force has not been managed after construction nevertheless it is one of the importrant factors that maintain the structural safety of PSC girder bridges. The prestressing force is just measured during construction using jacking device and after that, it can not be managed practically. For this reason, this study investigated the measurements of prestress using embedded sensors that can be available now with an ultimate goal to propose smart prestressed girders that can measure the prestress from the birth to the end of service life. 4 types of sensors were installed on the small prestressed girders, and the applicability and the accuracy of those sensors were tested while the prestress was applied to the girders. The results show that a center-hole type loadcell has a tendency to measure a prestressing force higher than a reference value, especially when it is loaded with an eccentricity. a EM sensor shows several advantages that has a good practical accuracy, that can be installed anyplace along the tendons.

Prestressing Loss Management for PSC Girder Tendon Based on EM Sensing

본 논문에서는 PSC 거더의 Prestress를 관리하기 위하여 EM 센서를 활용한 PSC 텐던 긴장력 손실 관리 기법을 소개한다. PSC 거더는 콘크리트 거더에 Prestress를 도입함으로써 기존 콘크리트 거더보다 높은 성능을 가지며 보다 저비용의 거더 설계가 가능해 짐으로 현재 많은 교량에 사용되고 있는 거더이다. 그러나 PS 텐던의 긴장력 관리는 거더 성능 관리에 있어 매우 중요한 항목이나 현재는 시공시 설계 긴장력의 도입 여부만을 검증한 후 공용시에는 그 관리가 이루어지지 않는 실정이다. 이에 본 연구에서는 강자성 재료가 인장력에 따라 비투자율이 변화하는 특성을 이용하여 EM 센서를 이용해 PS 텐던의 투자율을 계측하여 PS 텐던의 긴장력을 계측하는 기법을 제안하였다. PSC 거더 내부에서 PS 텐던의 투자율을 계측하기 위하여 EM 센서 시작품을 제작하였으며 MTS 실험을 통해 PS 텐던으로 주로 사용되는 7연선 1가닥의 0, 40, 80, 120, 160, 200kN의 긴장력에 따른 투자율 변화를 계측하였다. 계측 결과 각 긴장력 단계마다 EM 센서를 통해 계측된 B-H Loop가 정량적으로 변화하는 것을 확인하였으며 계측된 투자율과 긴장력을 회귀분석한 결과 투자율과 긴장력은 선형 관계를 나타내었다. 이를 활용하여 EM 센서를 이용하여 PS 텐던의 긴장력 관리가 가능함을 검증하였다.In this paper, an EM sensing based prestressing force estimation method is proposed, in which it can estimate tensile force of PS tendon for PSC girder. The PSC girder has more improved performance than the general concrete girder by introducing the prestressing to the concrete. Thus the PSC girder bridge is widely constructed due to its high performance and low cost. However, the prestressing force has not been managed nevertheless it is major factor for the maintenance of the PSC girder bridge. The prestressing force was just measured during construction using jacking device and after that, it can not be managed. For this reason, this paper proposes a tensile force estimation method of PS tendon based on EM sensor. The permeability of ferroelectric material is changed according to the induced stress to the material, in which it can be measured using EM sensor. To measure the permeability of PS tendon, the EM sensor was fabricated and verified by performing the MTS test. The test was performed using 7-wire steel tendon under the 0, 40, 80, 120, 160, 200 KN of tensile force. The permeability of PS tendon was gradually decreased according to the increasement of tensile force. The regression method was used to find the relation between permeability and stress. As a result, the permeability has linear relation with the tensile force of PS tendon and the pre-stressing force can be estimated by the derived estimation equation.

Structural Responses of Composite-girder Bridges Due to Design Live Loads using Distribution Factor Method and Grillage Analysis

Abstract In this paper, the modified live-load and designed formula are studied according to the fact the highway bridge design specifications are recently revised. The two examples for composite steel plates and PSC girder bridges are studied. The envelope is analyzed with the finite element models and lateral load distribution method applying the existing highway bridge specification(2010), the newly revised highway bridge specification(2015) and AASHTO LRFD. In case of composite steel plates, length changes between spans are studied, and in case of PSC girder. changes of the number of cross-beams and spans, and span-lengths, are analyzed. Keywords :Live load, plane grillage model, lateral distribution factor method, finite element method † Corresponding author: Tel: +82-31-290-7514; E-mail: kmye@skku.ac.kr Received October 17 2014; Revised January 21 2015Accepted February 23 2015Ⓒ2015 by Computational Structural Engineering Institute of KoreaThis is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons. org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

지점부 블록아웃 공법으로 연속화된 프리스트레스트 콘크리트 거더의 긴장력 손실 저감

Prestressed concrete girder bridge has been one of the most widely used bridges in the world because of its excellent construction feasibility, economic efficiency, serviceability, and safety. In certain situations, the prestressing tendon is supposed to be bent by the construction error and the radius of curvature at the continuous joint of PSC girders, and this leads to the loss of prestressing force. However, this kind of prestress loss is not considered in the design and construction processes. This study proves that the prestress loss occurs at the continuous joint due to the local bending of tendon by the construction error or the radius of curvature. Also, a method that can reduce this type of prestress loss is proposed, and proved by the experiment. The result shows that maximum 10% of prestress loss occurs at the continuous joint and the proposed block-out method can reduce the prestress loss ratio by maximum 5%, approximately. This means that the block-out method can enhance the prestressing efficiency of continuous PSC girder bridges.

Finite element model updating of a simply supported skewed PSC I-girder bridge using Hybrid Genetic Algorithm

Hybrid Genetic Algorithm (HGA) which combines the genetic algorithm as a global optimization and the simplex method as a local optimization is proposed for a finite element model updating of a real prestressed concrete bridge structure. In order to minimize the updating error between the measurement and the finite element model updating result, objective functions which are combinations of fitness functions based on the natural frequency, the mode shape and the static displacement are introduced. And an interface tool is also developed in order to utilize various element library and numerical analysis tools which are provided by commercial finite element and numerical analysis programs. A simply supported skewed PSC girder bridge which has 30 m span length is selected for the verification of the proposed FE model updating algorithm. Static vehicle loading test and forced vibration test by traveling vehicle as well as ambient vibration test were carried out to obtain the reference measurement data for numerical updating. A grillage model is used for the finite element analysis. Effect of the spring element to simulate the realistic support condition which is not perfectly free or restrained in real situation as well as that of the objective function on the updating accuracy are studied. From the result of parametric study, it is investigated that the use of spring element for support condition is effective to minimize the updating error for natural frequency and mode shape. Furthermore, including the static displacement fitness function together with those of dynamic properties may improve the global behavior of updated finite element model. It is concluded that the hybrid genetic algorithm proposed in this study is a very effective finite element model updating method to find an accurate result in updating real bridge structure based on measured data.

교각일체형 연속 PSC 거더교의 동적거동 특성 연구

건설환경의 지속적인 변화로 인하여 교량 건설비용의 최소화뿐만 아니라 공용기간중의 유지관리를 포함한 전체 비용의 최소화 및 최적화의 요구가 증가하고 있다. 이러한 이유로 교량의 상부구조에서 하부구조로 힘을 전달하기 위해 사용되는 교량받침 대신에 스터드나 연결철근 등과 같은 연결재를 사용하여 교량의 상부구조와 하부구조를 라멘식으로 일체화 시킨 교량형식이 제시되고 있다. 이 논문은 교량의 상부구조 형식을 연속 UD PSC 거더로 하여 철근콘크리트 교각과 일체화 시킨 교각일체형 연속 UD PSC 거더교를 대상으로 한다. 교각일체형 연속 UD PSC 거더교는 라멘교 형식과 거더교 형식을 결합한 교량으로 일반 받침형식의 교량과 상이한 거동특성을 나타낸다. 하지만 거동 특성에 대해 명확히 규명되어 있지 않다. 따라서 본 논문에서는 해석적 방법을 이용하여 교각일체형 연속 UD PSC 거더교의 동적거동 특성을 분석하고 2, 3경간 교각일체형 연속 UD PSC 거더교에 적용할 수 있는 충격계수 산정식을 제시하였다. Recently, the construction industry has been changed in such a way that the cost for bridge construction should be optimized or reduced. Therefore, bridges are required be cost-effective in terms of initial construction as well as in the maintenance during service stage. In order to reduce the cost for bridge construction, the Rahmen typed structure, in which the bridge components from superstructure to substructure are integral, has many advantages to reduce the size of structural members including girders, since the loadings from superstructure may be transferred to substructure through the connecting rebars such as stud, etc. This paper studied on the continuous Up and Down Prestressed Concrete (UD PSC) girder bridge in which the reinforced concrete pier cap is integral with the part of girders in superstructure. In previous studies, it is known that the structural behavior of continuous UD PSC girder bridge is quite different compared to the one of the bridges with conventional bearings or shoes to support the loading from girders. Nevertheless, it has hardly been studied about the structural behavior of bridge with UD PSC girder. Therefore, in this study, various dynamic behaviors of continuous UD PSC girder bridge with integral pier cap have been analyzed using numerical method. Furthermore, an equation to evaluate the impact factor is suggested for the UD PSC girder bridge which has two to three continuous spans.

BIM기반 신뢰성분석 및 수량산출서 자동화

최근 들어서 건축분야뿐만 아니라 토목분야에서도 정보통합 설계기법인 BIM 적용이 활성화 되고 있다. 이러한 과정의 일환으로 본 연구에서는 NATM 터널 1개소와 PSC 거더 교량 1개소를 대상으로 BIM 모델링을 통한 물량산출과 기존 2D 기반의 물량과의 오차율을 이용한 신뢰성 분석을 수행하였다. 또한 정보통합의 시작단계로써, 설계단계 BIM 활성화를 위한 국부적인 수량산출서 자동화 개발을 위해 BIM 기반 표준분류체계를 NATM 터널 및 PSC 거더 교량을 대상으로 안을 제시하고, 자동코드번호 입력 프로그램, 연동 및 수동물량산출 프로그램, 수량산출서 문서자동화 프로그램 등의 개발을 추진 중에 있으며, 이에 대한 단계별 절차와 방법을 제시하고자 한다. In recent years apply BIM, design method of information integration, the field of architecture as well as the field of civil engineering is activated. As part of this process, in this study, a NATM tunnel and PSC Girder bridge were the target. Quantities with BIM modeling and quantities with traditional 2D-based reliability analysis was performed using the error rate. In addition, as the beginning phase of information integration, quantity document automation program has been developed for activation of BIM. BIM-based standard classification system for NATM tunnel and PSC Girder bridge is proposed to target. And automatically enter the program code number, linkage and manual volume calculation program, quantity document automation programs, such as the development is now underway, and step-by-step procedures and methods are presented.

콘크리트 구조물에서 크리프 계수 추정 방법

콘크리트구조물의 시간의존거동을 예측하기 위해서 콘크리트의 크리프와 건조수축 등 시간의존특성을 묘사하는 모델을 이용한다. 그러나 크리프와 건조수축 모델 자체의 불확실성과 환경조건의 불확실성 때문에 이러한 모델을 이용하여 얻은 처짐과 실제로 측정된 처짐 사이에는 상당한 차이가 있다. 이러한 오차와 불확실성을 줄이기 위하여 실제 구조물에 이용된 콘크리트를 이용한 크리프 시험에 의한 결과를 이용하여 모델의 불확실성을 줄이는 노력을 하기도 한다. 하지만 이 방법도 실제 구조물이 놓인 환경조건을 정확히 모사할 수 없다는 점과 재료 자체의 불확실성 때문에 실험에서 얻은 크리프와 건조수축의 예측 값이 실제 구조물에서 발생하는 값과 다를 수 있다. 이 연구에서는 콘크리트의 시간의존거동에 영향을 미치는 요소 중 크리프에 대하여 살펴보고, 크리프 모델 불확실성 인자를 오차요인으로 고려하여 콘크리트 부재에서 측정된 처짐으로부터 크리프 계수를 추정하는 방법을 제시하였다. 이중 강합성 거더와 콘크리트 보 부재의 해석 예제를 통하여 이 연구에서 제시하는 방법의 타당성을 검증하였다. 이 연구에서 제시된 크리프를 오차요인으로 보고 크리프 계수를 추정하는 방법은 특히, 장지간 PSC 교량이나 콘크리트 사장교처럼 처짐이 중요한 형상관리인자인 경우에 구조물의 장기거동에 대한 합리적 예측에 도움을 줄 것으로 사료된다.

전단 지간의 변화에 따른 PSC 거더용 강-콘크리트 합성 바닥판의 역학적 거동

Recently, steel-concrete composite structures are widely used in bridge and building constructions. In this paper, a new type of steel-concrete composite deck with profiled steel sheeting is proposed to replace the conventional cast-in-place reinforced concrete deck. Perfobond rib shear connectors were utilized to provide horizontal shear resistance between the profiled sheeting and the concrete. To validate the effectiveness of the proposed deck system, 8 full-scale deck specimens for PSC girder bridge were fabricated. The specimens were tested with four different shear span lengths to determine the horizontal shear resistance of the deck under a static monotonic loading. For comparison purpose, two reinforced concrete decks were also fabricated and tested. The horizontal shear resistance of the proposed deck system was calculated using the m-k method.

Steel-concrete composite deck for PSC girder bridges

This paper introduces a steel-concrete composite bridge deck with perfobond rib shear connectors designed for the prestressed concrete I-girder bridges. The composite deck consists of profiled steel sheeting, perfobond ribs, reinforcements, and concrete. To provide horizontal shear resistance between the profiled sheeting and the concrete, perfobond ribs were used. For a prototype prestressed concrete I-girder bridge, two types of deck profiles with deck-to-girder connections were designed. To validate the effectiveness of the proposed deck system, full-scale tests for each deck profile and deck-to-girder connection have been condu cted. The results of tests have shown that the perfobond ribs can be effectively used for shear connection in the composite decks.

Analysis method for PSC-girder bridge deck slab with flexible girders

This paper deals with the assessment of load carrying capacity and safety of PSC-girder bridge decks. It has been observed from the result of load test and analysis that the differential deflection between girders in PSC-girder bridge deck reduces the negative bending moments in the deck slab. In this study, closed-form analysis method considering the effect of girder deflection is developed, based on the elastic plate theory. In this study, analytical solution with the elastic plate theory and numerical analyses with finite element modeling are performed and the results are compared with those of experimental studies for PSC-girder bridge. As a result, the differential deflection of the girders, which can greatly reducethe negative moments in a deck slab, tensile stresses of top slab is reduced. The analytical solution and 3-D shell modeling presented in this paper more accurate in estimating these results.