This paper describes the effects of local deformation, dent, and strain hardening properties on strain capacity in compression of a buried pipe.

 There were a few cases that the dents were found on the gas pipeline in Japan. Axial compression buckling experiment was conducted using the dented pipe and produced data such as stress-strain curves. Next, an analysis model that can reproduce the experimental results was established, and conducted various parameter studies. Those studies were the change in the depth of the dent, the internal pressure of the pipeline, earth pressure, and ground spring. The seismic integrity of the buried pipe was described in considering the depth of the dent, internal pressure, earth pressure and ground spring.

 It is generally known that with regard to the structures supported by considering large-scale foundations, input loss effect is expected due to the soil-pile interaction. Researchers, including some of the authors, have proposed a method for evaluating the input loss effect using the seismic deformation method that is generally used in design practice, and have shown its applicability to pile foundations with a pile diameter of about 1.5 m or less. On the other hand, when the flexural rigidity of the foundation body is large, such as the caisson foundation, the effective input motion may be amplified at low frequencies. Therefore, we generalize the seismic deformation method, then propose a method for evaluating both the amplification of effective input motion and the input loss effect by extending seismic deformation method. Furthermore, the validity of the proposed method is confirmed by comparing with the dynamic analysis results of the ground-structure integrated type for caisson foundations and rigid frame viaducts.

 Kumamoto Prefecture was severely damaged by the 2016 Kumamoto earthquake (M_j 6.5 foreshock and M_j 7.3 main shock). Especially in Kumamoto Castle, 30% of the entire stone wall was damaged by collapse and bulge. However, seismic retrofitting measures for castle stone walls have hardly been implemented because they have not been verified by experiments. Therefore, using the large-scale vibration test facility of the National Research Institute for Earth Science and Disaster Prevention in Tsukuba City, Ibaraki Prefecture, six models of seismic performance tests were conducted during the period from August 5 to October 14, 2019.

 In this paper, the contents and results of the large-scale experiment are mentioned. It was clarified that the geotextile roll-in type for stone bases and the anchoring method using urethane for non-stone bases are very effective with very few deformations.

 There are no official standard specifications and manuals for load-carrying capacity evaluation of existing bridges in Japan, and accordingly, most existing bridges are evaluated with design specifications for new bridges. In this study, a case study of load rating for five existing Japanese bridges with different structural types is carried out using the grillage analysis and 3D FEM analysis. Furthermore, the case study employs both current and previous versions of specifications and live loads for highway bridges to discuss rating results changes. The results show that rating factors depend on bridge types and increased dead loads due to retrofitting after completion. The rating factors based on the current design codes show larger values than those based on the previous ones, since the overall safety factor is decreased in the current codes. FEM analysis proffers the larger rating factors than the frame analysis used in design practices. The present case studies show that the rating factor is inversely proportional to the girder depth.

 When an ultra-high-speed train passes through a turnout hall in a tunnel, where a cross-sectional area abruptly changes, a compression wave is generated and becomes a micro-pressure wave at the tunnel exit. Since conventional measures such as a perforated device cannot be applied in a tunnel, we develop a new measure that utilizes a bypass tunnel across the turnout hall. When a train passes in front of the bypass tunnel, positive pulse waves followed by negative pulse waves are generated. By superposing these waves on the wavefront of the compression wave, we can reduce its pressure gradient which determines the strength of the micro-pressure wave. The dimensions of the bypass tunnel are calculated with a simple wave propagation model to obtain the optimum waveform to superpose. The pressure waves generated by a train passing through a turnout hall with and without the bypass tunnel are measured by experiment. The result shows that the maximum pressure gradient of the compression wave is reduced by about 40% with the bypass tunnel.

 The zinc-rich coating film has been used as an anti-corrosion primer of the heavy-duty paint coating for the steel structures exposed to the atmospheric environment. However, there are many unclear points about the corrosion protection properties of zinc-containing paints on those regions in steel structure, where the rainwater accumulated, and wet-dry cycles repeated. Moreover, the electrochemical mechanism of steel substrates between coating defects has not been investigated with elucidating its anti-corrosion properties. The objective of this research is to electrochemically elucidate the anti-corrosion properties of the steel substrate exposed at the adjacent coating defects of the organic and inorganic zinc-rich paints, focusing on the stagnated water and repeated wet-dry cyclic condition. Therefore, the model specimens were fabricated to simulate coating defects, and the time-dependent macrocell currents and AC impedance were monitored. Their test results revealed that for the inorganic zinc paints with relatively small diameters of defects, the anti-corrosion acts effectively due to the sacrificial anodic effects of zinc powder and compounds shielding. Nevertheless, the anti-corrosion effect of the organic zinc-rich coating is difficult to generate against the steel substrate.

 Since the 1995 Hyogoken Nanbu Earthquake, newly constructed bridges of Metropolitan Expressway have been designed or retrofitted to satisfy the required performance against Level 2 seismic motions, and existing bridges have been retrofitted to satisfy it. Therefore, the seismic performance of the bridges has been significantly improved in comparison with the bridges designed before 1995. On the other hand, the seismic performance of secondary systems, which is mounted on highway viaducts such as light poles and utility poles, has not been considered. Damages to their collapse or severe damages would affect both the loss of functionalities by themselves and disturbance of the emergency vehicles. In this study, we carried out an analytical examination with the integrated model of traffic sign structure and highway bridge altogether. From the acquired seismic responses, we examined that the maximum seismic response distribution along the sign pole can be assessed with a simplified estimation method of adoption of floor response spectrum based on interaction effect between traffic sign structure and highway bridge.

 A series of analysis and experiments were carried out to investigate the influence of residual stress reduction by local heating on the fatigue resistance of fillet box welded joints. The numerical analysis was conducted assuming the condition in which various magnitudes of tensile and compressive stresses were applied to the weld toe in the fatigue experiments on box welded joints with/without local heating for residual stress reduction. It was suggested that the improvement of fatigue resistance due to residual stress reduction may be greater when compressive stress is applied than when tensile stress is applied to the weld toe. The fatigue life of the locally heated joints was 4.9 – 10 times longer than that of the as weld joints in the stress range of 100 N/mm² by compressive cyclic loads.

 In riveted bridges, generally, rivets deteriorated with loosening and corrosion are replaced with high-strength friction-type bolts. In this case, both riveted and bolted connections which have different load transfer mechanism coexist in the same joint, however, the mechanical behavior and limit states of the rivet-and-bolt combination joints have not been well investigated yet. In this study, in order to investigate the mechanical behavior and limit states of the combination joints using rivets and bolts, static tensile tests were performed on specimens with different arrangement of rivets and bolts. Moreover, finite element analysis was performed to investigate load transfer mechanism in the combination joints. Based on the experiment and analysis, the evaluation method for the strength of the combination joints was indicated.

 It is generally known that with regard to the structures supported by pile foundation or caisson foundation, input loss effect is expected due to the soil-pile interaction. However, effective input motion at low frequency may amplify as compared to free field when the flexural rigidity of the foundations is large, as in the case of caisson foundations. In this study, in order to evaluate the effect of the flexural rigidity and the horizontal and rotational resistance of the foundations on amplification of the effective input motion, effective input coefficients targeting a single pile in a single layer ground at the primary vibration mode of the free field are evaluated by solving the differential equation of a beam on elastic foundation. From the evaluation, it is confirmed that the effective input coefficients asymptotically approach 1.0 when 𝛽𝑙 of a single pile is 2.0 or more regardless of the boundary conditions at the tip of the pile, while the effective input coefficients range from 0 to 1.2 depending on the magnitude of the rotational resistance at the tip of the pile when 𝛽𝑙 is less than 2.0. It is also confirmed that the amplification of the effective input motion is suppressed by restraining rotation of the pile head.

 This paper proposed a pushover analysis method for cut and cover tunnels that considers the interaction between the ground and the structure. In this method, seismic force and soil stiffness were evaluated based on the primary mode shape of the surface soil at each time step. The obtained soil deformation was then sequentially applied to the tunnel by a static non-linear analysis. It was confirmed through series of validation analysis that the seismic force and soil stiffness obtained by the proposed method showed good agreement with those obtained from dynamic ground response analysis. By using the proposed method, it is now possible to accurately calculate the section force of elements and damage process of the tunnel under earthquake without carrying out dynamic response analyses. In addition, this method is also applicable for the seismic design and performance verification of tunnels.

 Joint-type piping is often used in urban lifeline facilities because of its workability, but seismic resistance is ensured by the strength or deformation performance of the joint. The ground displacement resistance capacity is used to convert the performance against ground displacement that can be resisted. By substituting the conditions for each pipe into the idealized analysis model for evaluation, a guideline for seismic performance can be determined. Since the evaluation formulas currently used include a ground spring model and a model in which the ground spring yields, in this study, by assuming elasto-plastic type ground reaction force, two solutions are used to obtain the cross-sectional force of beam. Calculation formulas are proposed to determine resistance capacity of piping systems. Evaluation formulas that can be easily calculated with the minimum necessary parameters are useful for evaluating the seismic resistance of joint-type piping systems.

 One of the characteristics of the damage to the expressway embankment damaged by the recent earthquake is that there are many cases of joint openings, sediment outflows, and steps on the culverts. For these damages, we collected information such as embankment conditions, culvert conditions, ground conditions, and seismic motion conditions, and organized and analyzed the relationship with the amount of damage. From the results of macro analysis, “overburden”, “alluvial thickness”, and “earthquake ground motion SI value” were extracted as correlated parameters. From the results, we created a flow to select the points where countermeasures should be considered and a simple estimation formula for the maximum damage amount. This made it possible to determine the primary selection of whether or not countermeasures need to be examined and the priority of countermeasures with a certain degree of accuracy.

 Incident seismic waves at the engineering basement are frequently used for the numerical simulation of damaged structures and generally estimated using earthquake observation accelerations recorded at ground surfaces. The estimation method commonly used is based on frequency domain analysis such as analytical code, SHAKE. However, the equivalent linear approximation for non-linear ground characteristics in the estimation cannot give high accurate incident waves during strong earthquakes.

 In this research, we attempted to identify seismic incident waves at engineering basement based on the dynamic response analysis in time domain. As examples of identifying the seismic wave, the sinusoidal waves of the period of 0.1 and 2.0 seconds at the basement were input to a homogeneous multi-layer ground with linear characteristic in order to verify the availability of the proposed method. We introduced the weighted estimation step width to the procedure in identifying the input wave amplitude. As the results, the identified input seismic waves were decent accurate and the proposed method has a possibility of evaluating incident waves at engineering basement from ground surface observed records.