Segregation resistance and passing ability of high fluidity concrete with slump flow of 45 cm were investigated. The following findings were obtained as the results. (1) The Filling ability with passing between rebars is estimated by PJ value of the J-ring test. (2) The segregation resistance while passing between rebars is not matter too much. (3) The degree of settling of coarse aggregate is estimated by the ratio of coarse aggregate content in chamber B of the box-type filling test with vibration. Moreover, significant that due to excess compaction is estimated by visual examination of the slump flow.

In the seismic design of super high-rise buildings, a variety of challenges exist, including convergence calculation for setting design seismic force and evaluating cross-section, performance design against growing earthquake motion, and simultaneous case study analysis of damper placement and structural frame planning in an early design phase. To address these issues, this paper proposes an optimization method. This method uses a multi-objective optimization problem, using the response story shear force and response displacement distribution in elastic-plastic regions as performance indices. These indices are derived by the time history response analysis of a multi-degree-of-freedom (MDOF) system model.

A design algorithm is proposed for locally minimizing the structural cost of seismically isolated buildings. The design variables are the types and sizes of isolation devices, and the section sizes and reinforcement ratios in RC members in the superstructure. The design constraints are defined for the multiple properties evaluated in the response history analyses such as the lateral displacements and story shear coefficients. The effectiveness of the algorithm is verified in application to a seismically isolated building with a 21-story RC frame superstructure. A design possibility to reduce the cost in both the isolation layer and superstructure is demonstrated.

Causal hysteretic damping, extended Rayleigh damping, and uniform damping are models with frequency-independent damping ratios over a wide frequency range. However, there are many unclear points about its applicability to inelastic problems. Therefore, in this study, in order to compare the vibration characteristics of these damping models, analyses were performed by inputting white noise to multiple 1-degree-of-freedom model with different natural frequencies. As a result, it was confirmed that these damping models are frequency-independent even under inelastic conditions. Furthermore, causal hysteretic damping and extended Rayleigh damping can compute in the same computation time as conventional Rayleigh damping.

This paper attempts to apply reinforcement learning to the structural morphogenesis problem of grid shells. The proposed method uses an autonomous decentralized system, which has low computational cost and high versatility because it does not require re-training when the analysis model is changed. Iterative calculations on nodal neighborhood models are performed for the structural analysis, and Q-learning is used to learn shape modification rules that reduce external force work. Numerical examples show the results of the agent generating grid shells with high stiffness. It is also shown that it is possible to generate shells with an unlearned number of grids.

This study presents seismic performance of load bearing wall composed of CLT and RC frame. Element tests of various connections between CLT and RC block showed that the shear performance of CLT cotter is superior to other types, and it depends on vertical load and its shape. Based on this result, loading test on CLT wall with the cotter built in RC frame was conducted. Each specimen showed excellent toughness without brittle failure. These results led to design formula on initial stiffness and ultimate shear strength of CLT wall and RC frame with high accuracy.

Concrete short-span beams might suffer severe damage during a large earthquake. Steel Fiber-Reinforced Concrete is known to be effective for increasing the resilience of concrete members. However, there are not many studies that relate its material properties to improvement in structural performance of Steel Fiber-Reinforced Concrete members. Static loading tests using short-span Steel Fiber-Reinforced Concrete beams of the shear-failure type were carried out to evaluate its shear properties. Based on the experimental results including others, formulas to evaluate shear strength considering material properties were proposed.

This paper reports on long-term loading tests on a voided slab developed to reduce weight and improve workability, where the loading load was such that the tensile steel bars of the slab were at long-term allowable stress. The test specimen was part of a one-layer, one-span slab of a reinforced concrete building. The measurements are temperature, humidity, vertical and horizontal displacement of concrete slab, reinforcement strain, concrete surface strain, material axis strain on concrete standard specimens, strain on creep deformation specimens, and drying shrinkage.