Jian Yang

Anchorage force comprises bond force and bearing pressure when headed bars are used. Pull-out tests were conducted on 120 concrete specimens to derive a method for calculating the bond force for reinforcement in straight anchor sections at the yield moment. The parameters include the diameter d, embedded length l_ae, and yield strength f_y of the reinforcement, as well as the strength grade of the concrete f_cg. The experimental results indicated that the specimens underwent three failure modes depending primarily on the embedded length l_ae. The nominal average bond stress τ^u concept was proposed and the difference between τ^u and the actual average bond stress τ caused by the headed bars was observed. To reduce the difference between the τ^u and τ values, the correction coefficient γ was proposed. Analysis indicated that γ increased with an increase in the l_ae/d (on average, 146% higher than the initial value) and decreased with an increase in the f_y/f_t (on average, 33% less than the initial value). A formula was developed to calculate γ, and the bond force in the straight anchor sections at the yield moment for the reinforcement was determined. Thus, a distributive relationship was established for the anchorage force, the bond force, and the bearing pressure.

In order to study the seismic wave attenuation characteristics of complex plate tectonics in and around the Kanto Basin, based on the focal mechanism and Slab1.0 model, the research area is divided into four regions. The one-step non-parametric generalized inversion technique was used to analyze the seismic wave attenuation characteristics of each region separately. The results show that the seismic path attenuation of earthquakes occurring in the shallow crust (Reg.1) is weak, and the seismic wave refraction at the crust–mantle boundary leads to almost no attenuation over a long hypocentral distance (>60 km), the frequency–dependent inelastic attenuation is also weak with the 0.5–20 Hz quality factor Q = 92.33f^1.87. The seismic path attenuation of the upper mantle earthquakes occurring in the Kanto Basin (Reg.2) is strong, and the attenuation curve decreases with the increase of hypocentral distance, which is approximately parallel to the geometric diffusion R^−2.0, the frequency–dependent inelastic attenuation is stronger with the quality factor Q = 27.75f^1.08. The seismic path attenuation of subduction zone earthquakes (Reg.3 and Reg.4) is more obvious in the high–frequency band and has a frequency correlation, indicating that the attenuation of subduction zone earthquakes includes more inelastic attenuation. The frequency–dependent inelastic attenuation Q of Reg.3 and Reg.4 are 52.58f^0.95 and 58.07f^0.89, respectively.