Glass Fiber Reinforced Polymer is expected as the new material for infrastructures. In this study, the material strength test and exposure test were carried out to confirm the strength and deterioration characteristic of GFRP. In addition, the static flexural test was carried out to clarify the flexural behavior of pultruded GFRP I-section beam. From the material test and exposure test, it was confirmed that GFRP satisfied the design performance and had high durability. By the result of the static flexural test, it was clarified about the ultimate state of GFRP beam. The elastic beam theory could be apply to flexural behavior of GFRP beam. And also, it could be simulated by numerical analysis about the load carrying behavior of GFRP beam.
Recent considerable increases in traffic intensity and wheel loads are causing fatigue cracks in orthotropic steel decks. The author s have been studying methods of retrofitting orthotropic steel decks without need for traffic restriction for eliminating fatigue cracks originating fr om the weld between the deck plate and the trough and preventing fatigue damage. The following five retrofit methods (Case-1 to Case-5) are proposed in this study. a) Installation of stringers between the troughs (Case-1) b) Installation of splice plates between the troughs (Case-2) c) Filling of mortar in the troughs, in addition to the method of Case -1 or Case-2, respectively (Case-3 and Case-4) d) Open-cutting of the troughs and field welding of their insides (Case-5) FEM analysis and static load test are performed on fi ve full-scale bridge deck test panels to evaluate the stress reduction effect by the retrofit. And, fatigue tests are performed on two test panels before retrofit both after retrofit. This paper reports the re sults and, based on them, presents the recommended retrofit methods which do not require traffic re striction for existing orthotropic steel decks.
The steel plate bonding method is aimed at retrofitting the steel in a concrete member from outside by bonding steel plates to the surface of the concrete member using epoxy resin. The method has long been applied to numerous bridge decks. The uplift of steel pl ates have been detected with time. In this study, a reinforced concrete deck slab reinforced with bond ed steel plates on which uplift was artificially caused was developed to monitor the failure process under moving wheel loads in testing, and the deck slab was also repaired by re-injecting resin. Studies were made using the degree of deterioration. As a result, it was found that re-injection of resin improved the degree of deterioration to 0.69 even where the degree of deterioration was 1.3, higher than the serviceability limit(1.0).
The authors carried out a running wheel load test on RC slabs and proposed a mechanical model for the punching shear strength of RC slabs under running wh eel loads and the equation for evaluating the punching shear strength. The results showed a good agreement bet ween the punching shear strength determined from the test and that calculated from the equation. Next, the a uthors conducted a running wheel load test on RC slabs with different compressive strengths and evaluated the fatigue resistance of the slabs. The results showed that the fatigue resistance of the test specimen with a compressive strength of 32 N/mm2 was five times or more larger than that of the RC slab with a compressive strength of 21 N/mm2. In addition, the authors proposed an S-N curve determined from the relat ionship between the magnitude of a c ycle stress (S) to which the equation for evaluation of punching shear n ear the fracture load was applied and the number of equivalent cycles to failure (N). Consequently, the Matsui equation of S-N curve enabled us to evaluate the fatigue resistance of RC slabs with plain re-bars, and the proposed S-N is considered to be help in the evaluation of fatigue resistance of RC slabs with deformed re-bars.
The unseating prevention systems are installed in prep aration for the unexpectedly large seismic force or displacement due to larger intensity of ground motion, failure of the surrounding ground, etc. It is necessary to develop more reasonable design criteria and reliable procedures of unseating prevention system based on possible unseating scenario s. Based on observations of actua l damage from past extreme earth-quakes and analytical investigations, the required functions of unseating prevention devices and the effects of the structural propertie s of the devices are determined.
For steel plates multiple CFRP strips are bonded symmetrically to their both sides, the equations for estimation of the required length of CFRP strips to decrease the stress at the center of the steel plate to a prescribed value and the debonding shear stress at the ends of the CFRP strips are provided. Based on the theoretical solutions for the required length of CFRP strips and the debonding shear stress where one or two CFRP strips are bonded, the equations for the multiple CFRP strips bonded case are assumed, of which validity is investigated by FEM analyses. A numerical example reveals that there is a particular number of CFRP strips to decrease the stress at the center of the steel plate to a prescribed value without their peeling off.
The intercity expressway plays vital role to make the emergency vehicle immediately pass to the striken area in post-earthquake. For passing of emergency vehicle, it is necessary to introduce the two-way traffic in one side lane that has no damage. If the bridges where the traffic of both lanes connects are provided in an appropriate place of the expressway, two-way traffic in non-damaged side lane becomes possible. In this paper, we deal with expressway which is modeled as a ladder system with bridging capability. An analytical method of quantitatively evaluating the restoration process of the expressway system is proposed. Then, a recovery curves are presented to express and to understand the effect and functionality of the bridging expressway after strong earthquake. By numerical simulations using the proposed model of the bridging expressway system, seismic strategies appropriate for bridges in post-earthquake are discussed.
Fatigue cracks have been recently detected at welded connections between deck plates and trough ribs in steel orthotropic decks. The location of the cracks along the bridge longitudinal direction is the center of longitudinal rib span and connected part to the transverse rib. We already reported results of review in case of the center of longitudinal rib span. In this study, fatigue tests and finite element stress analyses on model specimens with two panels of steel plate deck have been performed in order to examine the influence of weld penetration depth, position of wheel load and scallop at the connection on fatigue durability and stress properties.
It is thought that needs of a client for timber bridge increase from rise or concern to environmental problem in addition to remarkable landscape. Recntly, hybrid structure reinforced wood beam with steel plate is proposed, it combines with the steel plate deck and is adopted in any real bridge. In such bridge, a joint is needed from workability, it is very important to know strength property of joint. In this study, we actually make the exact size specimen of a square steel tube-timber hybrid beem with a joint in the center to confirm its workability. In addition, we carry out load test, assessment its strength property by comparing experiment with FEM analysis.
Object prestressed concrete bridge with a 37.47m span vibrated greatly due to the resonation of the leaf suspension spring vibration arose from road roughness with the spatial wavelength near the expansion joint, only when the test truck ran in the 2nd slow lane. The bridge dynamic response affects the driver's riding comfort and the load-carrying capacity of the bridge. The monitoring was carried out for two years and five months in order to grasp the dynamic stress of the girders and the total weight of the trucks ordinarily running on the bridge. Moreover, the road roughness with a long spatial wavelength was repaired. After the repair, the same monitoring is continuing currently in order to compare with the data gathered about the dynamic response of the bridge before the repair. This paper describes the results of the dynamic response of the bridge resonated to the trucks' spring vibration arose from road roughness with a long spatial wavelength by monitoring before and after the repair.
This paper describes damping performance of buckling restrained brace (BRB) for seismic retrofit in an existing bridge frame. In particular, strength and stiffness of beam which supports BRBs are focused. The cyclic loading test for frame system with two types of BRBs and analytical studies for assessment of reproducibility and generalized character have been carried out in order to examine a variety of structural features. This research proposes the asymmetric bi-linear model for BRB and also presents that relatively weak beam of an existing bridge frame and BRB interact with each other, however they have an insignificant effect on damping property.
Structural behavior of a reinforce concrete (RC) slab subjected to re peated impact loads was investigated through falling-weight-impact tests. As a result of the tests, it was confirmed that the test slabs show punching shear failure after yield of reinfo rcement. It was examined how the repeated impact loads affected dynamic responses of RC slabs. In addition, an influenc e of slab specifications such as reinforcement ratio and thickness on structur al behavior of RC slabs was investigated.
In the view of recovery planning for lifelines damaged by earthquake, this paper seeks to develop a multi-agent simulation (MAS) for recovery process of lifelines. The process is formulated as a discrete resource allocation problem, and an MAS is used as a numerical method to solve it. The MAS takes advantage of object oriented programming, being capable of handling various kinds of lifelines as well as their engineers and users. Automatic model construction is studied. The validity of the MAS is veried by solving simple problems, and the potential usefulness is discussed.
For a box sectional steel column with transversely profiled plates (TP plate), cyclic loading tests, combined non liner FE analyses, pseudo-dynamic tests and dynamic FE analyses are carried out, in order to investigate its seismic performance. As results of cyclic loading tests and combined non liner FE analyses, it is shown that steel pier with TP plate have good seixsmic performances, and the taper ratio and the slenderness parameter are the larger, seismic performances are the better. And as results of pseudo-dynamic tests and dynamic FE analysis considering the real seismic acceleration, it is found that the response displacement of steel pier with TP plate is smaller than the one of ordinary steel pier.
This paper presents the effects of interface property and the shear connector profiles on fatigue failure mode of the steel-concrete composite bridge decks. According to the fatigue loading experiments, the composite deck with the initial chemical bond and the preceding contact friction is found to sustain the applied fatigue loads even after the occurrence of the fatigue cracks' band, in which the mode of member failure is the yielding of steel. Finite element analysis with the proposed interface model, which considers both the initial chemical bond and the contact friction, enables to reproduce this complex failure process. Furthermore, the analysis indicates that the different steel interface property creates the different failure processes of the composite decks subjected to the high cycled moving loads.
Float and counterweight type wave energy converter has solved the major part of the most serious problem of so called structural strength problem of the movable body type wave energy converter. However it still remains the problem that it experiences di fferent power intake torque between in the periods of ascending and descending of water level, and therefore the dangerous situation of sudden tight of the wire will occur after slacking in the wave cycles. In or der to avoid this situation, a method is devised to storage the power using the spring in a way of the wire in the system to flatten the temporal variations of the wire tension and electric power. This paper constructs the dynamics model for this energy conversion system, and evaluates the effects of the power storage on the system operation. The function of the power storage is considered as the change in the length of the wire between the driving pulley and float. Calculations predict that the power storage suppresses the occurrence of negative wire tension, that it increases the time averaged electric power, an d that the power storage is effectiv e for waves with shorter period and higher wave height.