• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1519-1525
• /
• 2011

Construction of the coping of reinforced concrete piers is very complicated due to heavy density of rebars and usually exposed to negligent accident. To correct these problems, coping is pre-assembled at the ground in pier coping pre-assembly method and recently a new method of rebar assembling has proposed in this study. For safety assessment of proposed method, small scale model test of railway bridge(PSC U-GIRDER T-shaped pier) was carried out and it was verified that crack pattern, failure mechanism and load resistance capacity are similar between existing method and proposed method. And using analytical approach, linear and non-linear finite element analysis was performed. As a result, it was checked that proposed method has an acceptable structural safety.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.177-178
• /
• 2009

This study is based on the precast concrete bridge which recently became important field of bridge construction. to develop the connecting technology of pier and footing, the purpose of this study is to verify applicability through the result of nonlinear analysis.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.53-54
• /
• 2009

Steel-embedded composite piers provide flexible design alternatives to satisfy the required performance due to various design parameters of composite sections. For the fast construction of composite piers, bolt connection can be utilized for small size piers and post-tensioning to the pier segments for the large size piers. In this paper, experimental results on composite piers were investigated to evlauate the effects of design parameters on the behavior of composite piers. Appropriate sections and their integration methods were suggested according to the design conditions. For the modular construction of bridge piers, pier segments need to be divided considering their weight and careful considerations on details to adjust fabrication and construction error. Connection details for the pier cap were also proposed.

• Structural Engineering and Mechanics
• /
• v.58 no.2
• /
• pp.199-216
• /
• 2016

A large number of bridges were built several decades ago, and most of which have gradually suffered serious deteriorations or damage due to the increasing traffic loads, environmental effects, and inadequate maintenance. However, very few studies were conducted to investigate the vibration behaviors of a damaged bridge under moving vehicles. In this paper, the vibration behaviors of such vehicle-bridge system are investigated in details, in which the effects of the concrete cracks and bridge surface roughness are particularly considered. Specifically, two vehicle models are introduced, i.e., a simplified four degree-of-freedoms (DOFs) vehicle model and a more complex seven DOFs vehicle model, respectively. The bridges are modeled in two types, including a single-span uniform beam and a full scale reinforced concrete high-pier bridge, respectively. The crack zone in the reinforced concrete bridge is considered by a damage function. The bridge and vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact points between the tires and bridge. The numerical simulations and verifications show that the proposed modeling method can rationally simulate the vibration behaviors of the damaged bridge under moving vehicles; the effect of cracks on the impact factors is very small and can be neglected for the bridge with none roughness, however, the effect of cracks on the impact factors is very significant and cannot be neglected for the bridge with roughness.

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.19-26
• /
• 2007

Until recently Korea is considered to be immune from the earthquake hazard because it is located for away from the active fault. However, we have noticed that recent strong earthquakes inflicted enormous losses on human lives and nation's economy all over the world. Hence, there has been raised the importance of the earthquake resistant design for various infrastructures. In this research, new methodologies for the seismic design and performance assessment of reinforced concrete(RC) bridge pier were proposed from experimental results of 82 circular RC bridge piers and 54 rectangular RC bridge piers tested in domestic and aboard. New seismic design method was based on the concept of the limited ductile design, which could be practically used for low or moderate seismic regions like Korea. Further study for the seismic safety of RC bridge piers was carried out to enhance the seismic performance of aged RC bridge piers, which were designed and constructed before implementing the 1992 seismic design provision in Korea. New formula for the seismic performance assessment of RC bridge piers was proposed and practically used for the decision on the need of repair and retrofit of many aged RC bridge piers.

• Journal of the Korea Concrete Institute
• /
• v.18 no.6 s.96
• /
• pp.749-757
• /
• 2006

Many losses of life and extensive damage of social infrastructures have occurred due to moderate and strong earthquakes all over the world. In this research various design parameters have been evaluated to develop a rational seismic design code of rectangular reinforced concrete(RC) bridge piers. It was confirmed from this study that the axial force ratio and longitudinal steel ratio were most influencing design parameters on the seismic displacement ductility from experimental results of 54 rectangular RC bridge piers, which were tested at domestic and foregin countries. However, these important parameters are not considered in the confinement steel ratio of Korea Highway Bridge Design Specification(KHBDS). The objective of this study is to propose a rational design provision for the transverse reinforcement of rectangular RC bridge piers. New confinement steel ratio is proposed by reflecting the effect of the axial force and longitudinal steel into the current code of KHBDS. furthermore, minimum transverse confinement steel ratio is also proposed to avoid a probable buckling of longitudinal reinforcing steels of RC bridge piers with a relatively low axial force. New practical code can alleviate the rebar congestion in the plastic hinge region of RC bridge pier, which contributes to construct RC bridge piers in a simple and economic way.

• Computers and Concrete
• /
• v.23 no.6
• /
• pp.445-457
• /
• 2019

Cracks are an important distress of concrete bridges, and may reduce the life and safety of bridges. However, the traditional manual crack detection means highly depend on the experience of inspectors. Furthermore, it is time-consuming, expensive, and often unsafe when inaccessible position of bridge is to be assessed, such as viaduct pier. To solve this question, the real-time automatic crack detecting system with unmanned aerial vehicle (UAV) become a choice. This paper designs a new automatic detection system based on real-time comprehensive image processing for bridge crack. It has small size, light weight, low power consumption and can be carried on a small UAV for real-time data acquisition and processing. The real-time comprehensive image processing algorithm used in this detection system combines the advantage of connected domain area, shape extremum, morphology and support vector data description (SVDD). The performance and validity of the proposed algorithm and system are verified. Compared with other detection method, the proposed system can effectively detect cracks with high detection accuracy and high speed. The designed system in this paper is suitable for practical engineering applications.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.3 s.55
• /
• pp.23-31
• /
• 2007

Fast bridge construction has been increasingly needed according to the changed construction environment. This paper deals with quasi-static tests on precast piers for bridge substructures. One of the most crucial aspect of the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier elements were fabricated. The amount of prestressing bars, the prestressing force, and the location and number of the joint between segments were the main test parameters. Test results showed that the introduced axial prestress made the restoration of the deformation under small lateral displacement and minor damage. However, there was no effect of the prestress when the plastic hinge region was damaged severely due to large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should be done for the first joint between the foundation and the pier segment. The amount of the necessary prestressing steel may be designed to satisfy the P-M diagram according to the service loads, not by having the same steel ratio as normal RC bridge piers. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of the transverse reinforcements as RC piers. As the steel ratio increases, the energy absorption capacity increases. The number of joints showed a little influence on the energy absorption capacity.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.4
• /
• pp.2399-2405
• /
• 2014

A fish-bone type bridge is vulnerable to the torsional behavior due to the single girder system with planar zigzag conformation. The fixed connecting area between the girder and pier is the special weak point because the torsional load creates excessive stress concentration. Therefore, the method to reduce the stress concentration is required. In this study, the reduction efficiency of various reinforcing types to reduce the excessive stress occurring at the connecting area is evaluated by using numerical analyses.

• Earthquakes and Structures
• /
• v.15 no.4
• /
• pp.419-429
• /
• 2018

The seismic vulnerability analysis of multi-span bridges can be based on the response of the piers, provided that deck, bearings and foundations remain elastic. The lateral response of an RC bridge pier can be affected by different mechanisms (i.e., flexure, shear, lap-splice or buckling of the longitudinal reinforcement bars, second order effects). In the literature, simplified formulations are available for mechanisms different from the flexure. On the other hand, the flexural response is usually calculated with a numerically-based Moment-Curvature diagram of the base section and equivalent plastic hinge length. The goal of this paper is to propose a simplified analytical solution to obtain the Moment-Curvature relationship for hollow circular RC sections. This based on calibrated polynomials, fitted against a database comprising 720 numerical Moment-Curvature analyses. The section capacity curve is defined through the position of 6 characteristic points and they are based on four input parameters: void ratio of the hollow section, axial force ratio, longitudinal reinforcement ratio, transversal reinforcement ratio. A case study RC bridge pier is assessed with the proposed solution and the results are compared to a refined numerical FEM analysis, showing good match.