Young's modulus of wood is an index to evaluate the strength property of deformation and to classify the strength of wood nondestructively and accurately. If the Young's modulus of wood and wooden structural members could be measured in service, it would be possible to estimate the deformation and bearing capacity under external forces without dismantling the structure or recovering the members. However, when Young's modulus of actually driven wooden piles is evaluated under cantilever beam models, the difference between theoretical and measured values is significant, and the measurement method needs to be simplified and made more efficient to be applied to actual construction sites. In order to develop a technique to evaluate the Young's modulus of a wooden pile driven at a construction site, we investigated a method to measure the Young's modulus of a cylindrical timber with a part of its length driven into the soil. As a result, an inclinometer was found to be effective.

 In recent years, there are case of applying CLT deck to road bridge decks. Most of general road bridge slabs are made of reinforced concrete. If CLT is applied to replace the existing RC slab, it can be expected to prevent the increase in dead load. However, consideration of mechanical characteristics of CLT slab with different support condition is not implement. The purpose of this study is to investigate the mechanical characteristics of CLT with different support condition, and consider the layer composition. As a result of this study, deflection is reduced when parallel layer is placed on outside, and difference of displacement and stress with support condition is small.

 To develop a new application for cross-laminated timber(CLT) in the civil engineering field, we focused on floor deck materials used for bridges and considered using CLT floor slabs to replace the floor slabs of existing bridges. When bridges are modified to meet modern design loads, in some cases, the primary girders require reinforcement owing to increased reinforcement concrete (RC) floor slab thickness. If the RC floor slabs can be replaced with CLT floor slabs of similar cross-sections, as CLT floor slabs have lesser weight, the modifications can be completed without reinforcing the girder. In this study, the feasibility of using CLT slabs is investigated for an existing forest roadway bridge in Hokkaido, where floor slab replacement work is planned, by analysis using the finite element method.

 The function that can be passed so as not to feel the obstacle while the pedestrian is walking is necessary for the pedestrian bridge.The countermeasures for the pedestrian not to become unpleasant feeling vibration by the deflection limitation and the vibration frequency limitation are necessary, when the pedestrian bridge is designed. Moreover, it is necessary to verify the realities of the vibration serviceability by the experiment and the analysis for maintenance under use. However, the study on the vibration serviceability of timber pedestrian bridge is still few current states, though there are a lot of researches on the steel and concrete pedestrian bridges from the past. Especially, the study on the vibration serviceability of timber pedestrian bridge by passage year is very few.

 In this study, the vibration test in real bridge was executed for the timber arch pedestrian bridge of 17 years passed after, and the realities of the vibration usability were investigated. Moreover, the vibration serviceability is investigated from the change in the vibration characteristics by passage year based on the vibration testes of two times in the past. In addition, the consideration was added to the relation between vibration serviceability and soundness by passage year in this study.

 This study is on the erection tests of a full scale emergency bridge with 10m span by two type ; one is the erection of panel connection, the other is the erection of folding/unfolding of bridge. The tests is executed in the gym and the ground in the Hakodate National College of Technology. In the test of the panel connection, total erection time is 3 hour and 35 minutes worked by 10 workers. On the other hand, it takes 2 hour and 30 minutes to complete the erection by the folding/unfolding erection worked by the same 10 workers. In the folding/unfolding test, a pseudo river and a construction site are settled in the ground and the folding bridge is erected by using 13tf rough terrain crane. Thus the erection tests is executed under near the real condition, and erection time is short. Therefore, this bridge has good application to emergency situation.

 Agricultural water channels called creek around Ariake coastal area have been used without revetment, however banks of creek have been collapsed gradually. Maintenance work of them is a burden on the adminisitrative office because of great distance.

 Revetments made of concrete have high durability. However they are much expensive, so there is no enough budget which concrete revetments are constructed completely. On the other hand, revetments made of wood can be construnted cheaply, however they are not durable and installed positive preservative treatment. It is possible that durability of wooden revetments can dramatically improve if several knowledges are installed.

 Wooden revetments aim for high durability were constructed in 2014. Test specimens to inspect durability were also installed in the same place. Discussion for aging degradation of them is reported. It has been obtained that high durability wooden revetments can be realized.

 When installing concrete or steel check dams, the ground support at the bottom of the check dam may be inadequate. One of the countermeasures for such situations is to reinforce the ground by driving wooden piles into the foundation of the check dam. The formula for calculating the bearing capacity of wood piles is based on that for pine trees. The applicability of the formula in its unmodified form to cedar piles, which have been considered in recent years, is yet to be confirmed. Therefore, to determine the bearing capacity when cedar piles are used in the foundation of the check dam instead of conventional pine piles, we perform vertical loading tests of cedar and larch piles. After the test is completed, the test piles are accumulated and subjected to a longitudinal compression test to evaluate their compressive strength.

 The results show that the bearing capacity and compressive strength of cedar are lower than those of larch. To calculate the bearing capacity when cedar is used as piles, a correction formula obtained by multiplying the conventional bearing capacity formula by 0.7 to 0.6 should be used.