In the years to come, Korea will have the privilege to become the country presenting the most diversified bridge construction activities that will constitute precious case studies for the international bridge community. Until 2011, about 50 major bridges with various types will link some of the 3,000 islands of the peninsula to the mainland, which are taking place in the ambitious plan for building an efficient national transportation network and set the bases for the future strategic hub of Northeast Asia. In order to sustain this unprecedented construction activity of infrastructure systems and the encouraging technological accomplishments that have been acquired to date, the Korean R&D community agreed with the necessity to prepare for the next generation of construction technology. There is a clear need to develop and construct a new generation of high performance facilities by means of enhanced materials, advanced structural systems and technologies as well as upgraded or improved specifications or standards in a lifetime perspective.
This paper identifies some major technical issues and challenges for the next generation of bridge and addresses relevant and systematic construction-related R&D programs in Korea. Among them, the Korea Bridge Design & Engineering Research Center (KBRC) has been launched in 2004 as a national research program of the Ministry of Construction and Transportation to be the core of new research and technology transfer program in the area of bridge technology and expedite the process of full transition to the reliability-and performance-based bridge design codes and specifications in Korea. Other large R&D programs are also reviewed in terms of durability and lifecycle cost with lifetime perspective like the Bridge 200 R&D project of the Korea Institute of Construction Technology and high-performance materials like the High Performance Construction Material Research Center (HIPER CONMAT).

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This study describes an analytical proposal to predict lateral shear capacity of confined masonry walls that fail by diagonal splitting, where the maximum shear is evaluated as the dowel action of confined columns' reinforcement added to the shear capacity of the plain masonry panel. In order to validate the proposed approach, experimental test results and gathered data from literature were used. The experimental tests concerned two confined clay brick walls subjected to different level of gravity load and cyclic lateral loading. The applicability of some empirical formulae found in literature regarding the stiffness degradation was investigated. Good correlation between the predicted lateral resistance using the proposed approach and all data was achieved.

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In this study, the mechanisms associated with the seismic response of a long-period structure when subjected to a long-period seismic excitation are clarified. A typical scale cable-stayed bridge with prestressed concrete girders (PC cable-stayed bridge) was selected for analysis. First, we simulated long-period components of the ground motion at the site of the Ji-Lu Bridge, which was damaged in the 1999 Chi-Chi, Taiwan earthquake, and the damage of the bridge was assessed by nonlinear seismic analysis using the simulated ground excitations. Second, shaking table tests of a model PC cable-stayed bridge were carried out, in consideration of the similarity law, to clarify the mechanisms involved, focusing on the linear and nonlinear seismic responses of the tower and cables.

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A new bridge foundation named “Sheet-pile foundation” is proposed. Sheet-pile foundation consists of a footing and sheet piles surrounding the footing. By installing sheet piles into the ground around the footing and connecting together, both overturning and sliding resistance of the foundation against the seismic action will be increased. This technique can be applied as the seismic retrofit method of foundations as well. In this study, the seismic performance of the sheet-pile foundation is experimentally investigated. 2 series of shaking table tests under the centrifugal gravity were performed, with utilizing model foundations with 5m square footing as the prototype.

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The effect of vehicle existence on the seismic response of highway bridges is investigated by means of a three-dimensional dynamic analysis considering the bridge-vehicle interaction. A dump truck is assumed to be represented sufficiently by a discrete rigid multi-body system with 12 degrees of freedom. The Level 1 ground motions determined by the seismic design code of Japan Roadway Association and observed earthquakes are used in analysis. The slip of a heavy dump truck is also evaluated during the ground motion. Observations demonstrate that the existence of heavy vehicles, which are also dynamic system, can decrease the seismic response of bridges.

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In this paper a methodology on seismic risk evaluation of fill dams is proposed, where sliding displacement of the soil mass along the failure surface is considered with Newmark sliding block model. The feature of this study is the probabilistic evaluation of the seismic risk. Considering variabilities of sliding displacement, fragilities of various types of fill dams are evaluated defined as the conditional probability of exceeding allowable displacement of the sliding mass for given intensity of the ground motion. With the fragilities and the seismic hazard, annual probabilities of failure of the fill dams are calculated showing the seismic risk level of the existing fill dams designed by conventional design method is of the order of 10^-5 or less and comparable with or less than other important civil engineering structures.

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Attenuation relationships are proposed for acceleration response spectrum and Fourier spectrum of ground motion in rather-long period range using strong motion records observed in Japan. Amplification maps are also developed to compensate the attenuation relationships for site amplification characteristics. Comparisons with the ground motion calculated by a three-dimensional finite difference method validate the attenuation relationships and amplification maps. Ground motion during hypothetical great earthquakes is estimated by the present method, showing the method enables site-specific ground motion prediction at arbitrary sites all over Japan.

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In daily inspection for concrete structures, inspectors assess the integrity of them based on visible information such as cracks first. This study carries out damage detection using Support Vector Machine and Learning Vector Quantization for concrete slabs with cracks for the purpose of the development the integrity assessment system. These pattern recognition methods are used to learn the characteristics of the damage of the concrete slabs. The efficiency and applicability of proposed methods are discussed through the classification of the magnitude of damages extracted from photographed images of concrete slabs with cracks.

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Characteristics of risk of natural disasters are studied based on available statistics of Japanese long term historical data and intenational data on damage loss. Not only intensity but also mode of risk expressed in terms of the ratio between losses of human lives and properties is found important and useful to investigate the risk characteristics. Based on these findings, risk, vulnerability and hazard are modeled by linear multiple input and multiple output system, and norms of vulnerability and hazard are identified based on this model. The structure of vulnerability is shown to change with respect to economical development, and several useful findings on natural disaster risks are derived based on this model.

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In Japan, a steel-plate concrete composite deck which is connected concrete and a steel-plate with shear studs, is called Robinson type. In order to decrease deflection of the steel plate when fresh concrete is casting on, the steel plate is stiffened with steel strips. In recent years, the composite deck is applied to many high way bridge decks. One of the predominant fatigue damage modes of the composite deck was detected as shear-off failure of the studs by repetition of wheel loads. In this paper, three-dimensional finite element analyses of mid span part and overhanging part specimens for wheel trucking tests were conducted to evaluate characteristics of shear forces of the studs. Furthermore, comparison between analytical values and experimental results of these specimens, fatigue strength of the studs was investigated.

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The purposes of this research were to confirm the seismic isolation effects of bearings in a PC road bridge of two continuous spans employing high-damping rubber bearings (seismic isolation bearings), based on 27 seismic waves observed in the entire bridgesystem, and to verify the validity of the seismic isolation bearing design method employed for this bridge.
The results indicated that the seismic isolation of the beams could be confirmed from the acceleration and relative displacement waveforms contained in seismic observations, and that the equivalent stiffness of the bearings, as calculated from seismic observation values, is consistent with the values employed at the design stage, and with the values obtained in vibration experiments using vibration generators. Therefore, this research was able to verify the validity of the design method employed for the seismic isolation bearings of this bridge.

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In this research, tensile tests are carried out for the structural aluminum alloys 6061-T6, 6N01-T5 and 5083-O. Application of a probability-statistical approach to the test results shows that the Young's modulus and the strain-hardening parameter are expressed by a normal distribution and a lognormal one, respectively. The relations between stress and strain are formulated, using the values corresponding to the 5% probability of not being exceeded for the Young's modulus and the strain-hardening parameter. Furthermore, tensile tests are carried out for butt connections fabricated by MIG welding and FSW, and he relations between stress and strain are formulated for MIG welds and FSW joints. Based on the measured residual strains, the residual stresses are formulated with a rectangular distribution.

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This paper presents the applicability of CFRP adhesion for the repair of corroded steel members. To improve the strength of debonding, we carried out tensile tests and FE analysis that paid attention to the method of finishing up the ends of CFRP. As a result, it was confirmed that it was effective to the improvement of the strength of debonding to move the edge in the CF sheets. Moreover, the strength of debonding and the effect of the repair when patching to the section loss part of the steel member were verified. Based on these results, the repairing methods by CFRP adhesion were presented.

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Evaluation of life-cycle cost (LCC) is essential for efficient management of civil infrastructure. Because civil infrastructure has substantially longer service life than that of industrial product, and requires replacement due to its involvement with public interest, conventional LCC evaluation method developed in engineering economy is not directly applicable. To reflect these characteristics of civil infrastructure, infinite-horizon LCC is formulated and applied to evaluation of various maintenance strategies based on available past data. The proposed method is found to yield average cost method which widely used for LCC analysis civil infrastructure and have the capacity to assess the effect of routine and preventive maintenance.

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At an intermediate support of continuous composite girder bridge, the compressive stress is generally introduced into the concrete-slab to improve the serviceability limit state of girder. The main method for introducing the compressive stress is jack-up-and-down or PC-bar methods. These methods can improve the serviceability limit state, whereas they cannot improve the ultimate limit state of bridges. The authors have been studied thermal prestressing method by using the stiffning members in order to improve the serviceability limit state of girder. In this paper, the experiment of loading test for two-span continuous composite girder model by applying this thermal prestressing method is presented herein and then the effect of improvement conserning the ultimate limit state, i.e. ultimate strength of girder by this method is discussed concretely through the comparisons with analytical results.

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The residual load carrying capacity of a plate girder end panel with a fatigue crack around the sole plate subjected to predominant shear force is investigated experimentally and analytically in this study. First of all, the experiment is carried out using 3 types of the test specimens with cracks of different length. Then, elasto-plastic and finite displacement analysis is conducted varying the crack length for investigating the influence of the crack length on the residual load carrying capacity. It can be found through the experiment and analysis that the load carrying capacity of the plate girder end panel with a crack passing throughout the cross section of the lower flange plate and penetrating the lower web part shorter than 1/6 times the web height does not decrease significantly compared with that of the intact plate girder end panel without crack. Finally it is suggested that the residual shear buckling capacity of the plate girder end panel with the crack can be approximately and accurately evaluated by using the plate slenderness parameter R_τw using the reduced aspect ratio considering the location of the crack.

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The deterioration processes of civil infrastructures are heterogeneous due to unobservable factors even under the same structural and environmental conditions. In this paper, a Markov hazard model is formulated to characterize the average hazard rates, and is extended to a mixed Markov hazard model by incorporating the heterogeneity in hazard rates. By doing so, the benchmarking model to express the average deterioration processes and the statistical methodology for comparative assessment of the hazard rates of the individual facilities is also presented. The applicability of the methodology presented in this paper is examined against the real world data concerning the bridge members.

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In this study, a system of scene evaluation and the computer-aided design of girder bridge is proposed for quick responce in an agreement formation stage using XML which can also peruse the Internet using the analysis result by the sensitivity engineering technique of girder bridge. In addition, the example of a bridge and the display method of a score which agreed as a policy for supporting a scene design in the evaluation simulation and two or more design concepts accompanying category change were proposed. Moreover, in order to examine the usefulness of the built system, comparison with the example of a scene design of a real bridge was tried, and the validity of an output result was considered.

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An effective reinforcement method for the side wall of a cut and cover tunnel has not been established yet. We develop a new seismic countermeasure of the under ground structure based on new concept. In this method a polymer material whose stiffness is quite flexible, is embedded both sides of the tunnel.
We examined the factor that the section force decreases by using the proposed isolation method. The factor is a covered soil, and a ratio of the stiffness between the ground and the structure. It was found that these factors were related to the effect of the isolation method. We proposed a simple chart. We can judge the effect that the section force decreases by using the chart.

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To evaluate the impact behavior and the residual strength of RC protective structure under repeated impact load is essential for building of performance based design method of protective structure. In this study, damage condition of RC beam under single impact load was clarified by using Lemaitre's damage model, which can evaluate stiffness degradation of damaged materials for unloading/reloading. Further, a new cumulative damage model was proposed. By using the model, the residual strength and allowable impact condition were evaluated based on cumulative damage level of RC beam under repeated impact load.

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The mechanism of imperfection sensitivity of elastic−plastic plates under compression is complex as they undergo elastic and/or plastic buckling, dependent on their width−thickness ratio. The Koiter power law is extended by implementing the quadratic law so as to describe the elastic and plastic buckling of the plates with probabilistically varying initial deflection and yield stress. The finite-displacement, elastic−plastic analysis was conducted on simply-supported square plates under compression by varying the plate thickness, yield stress, and the initial deflection of a sinusoidal form. In accordance with the change of the mechanism of buckling, the power law is changed pertinently to describe the complex imperfection sensitivity of the compression plates in a synthetic manner. A theoretical framework to describe the probabilistic variation of the ultimate strength of the plates has been proposed, and has been put to use in the evaluation of the influence of width−thickness ratio.

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Formulation for load-slip relationship of shear connector is necessary to rational design of composite structures. Pushout tests of headed stud connector were carried out under various stud diameter, stud strength, stud height/diameter ratio and concrete strength. Load-slip relationship can be represented by one equation with dividing shear force by shear strength and slip by stud diameter. The form of load-slip relationship depends on concrete strength, stud height/diameter ratio and stud strength. Equations for the enveloped curve of load-slip relationship taking account of these effects and slip-residual slip relationship were proposed.

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Checking the seismic safety of dam-gate systems in addition to the dam body is an essential requirement. In this paper, the present design standards and studies on dam-gate are summarized. As a case study, shaking table tests and numerical analyses were carried out, with findings that hydrodynamic pressures expressed by the Westergaard equation was likely to give overestimation for dam-gate systems. The overestimation resulting from positional effects of the dam-gate systems were evaluated. Finally, simple procedures to reduce the overestimation were proposed for practical application.

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In the XFEM, elements with some of their nodes enriched are usually called 'blending elements (BE)'. Decrement in accuracy of the analytic solution in BE is associated to a lack of partition-of-unity. In this paper, the influence of BE on the analytical accuracy of fracture mechanics parameters based on J-integral method is first evaluated. Then, a newly proposed modeling methodology on the domain of enrichment, considering the J-integral path, is presented. This methodology is straightforward allowing avoidance of the direct influence of BE on the analytical accuracy. Therefore, analyses with sufficient accuracy in the minimum enrichment domain are effectively achieved by using the proposed methodology.

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This experimental research aims to examine a fatigue behavior of concrete slabs and headed studs in a continuous steel-concrete composite girder under negative bending. In particular, the fatigue behavior near the intermediate supports is fully investigated by using test specimens. It follows from the present experimental study that the bond between studs and concrete and the bond between flange plate and concrete become weak after the fatigue loading, and that the tension stiffening effects of the concrete slabs are expected except the intermediate support where the negative bending moment becomes largest.

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An agent simulation is developed to predict unorganized emergency evacuation process of crowds consisting of various people. An agent is able autonomously to see, think and move; the distribution of its speed is the same as the walking speed distribution which is measured by analyzing video images of people running in an emergency state, and a model for an evacuation space is automatically constructed from digital data which are stored in GIS or CAD. The simulation is carried out to a network of narrow streets, subway stations and a large underground shopping mole. It is shown that the developed agent simulation is able to simulate unorganized state of mass evacuation and to analyze risk of the evacuation space.

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Now, in Japan, the security distance in the explosive magazine is simply regulated to set by the rule of K-value and the amount of storage explosives. This regulation is on a basis of explosion in a free air. However, the peak over pressure of blast wave induced by the inner explosion of earth covered explosive magazine may be reducible. In this study, to find the effects of covered soil on the blast wave properties due to the inner explosion of earth covered explosive magazine, small scaled explosive tests were executed. In tests, the 1/20 scaled model magazines were exploded under the conditions of different amount of C4 explosive (10-50 g) and thickness of covered soil (0-15 cm). From test results, it is found that the peak over pressure is obviously reduced by the increase of covered soil thickness. Thus the curtailment of security distance is presented to receive or parallel with the present domicile situation.

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Consolidated Carbon Fiber Plate (CCFP) has significant tensile strength and higher applicability, so it is often employed for strengthening of RC member. The present study focused on anchorage methods of CCFP for cantilever RC slabs subjected to negative bending moment. As the fundamental experiment, bending tests were conducted by using beam specimen with various anchorage methods. Based on the fundamental experiment, we have devised the simplified method that embed CCFP in the surface of RC member. In order to investigate applicability of the anchorage method, the wheel running fatigue test was conducted by using a cantilever RC slab strengthened by CCFP.

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An effective reinforcement method for the side wall of a cut and cover tunnel has not been established yet. We develop a new seismic countermeasure of the under ground structure based on new concept. In this method a polymer material whose stiffness is quite flexible, is embedded both sides of the tunnel.
We examined the method constructed outside of the tunnel. The method is a polymer isolation method, the soil improvement method, and the RC diaphragm wall. It was found that the polymer isolation method was effective and practicable for seismic countermeasure.

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