Shear Strength of Reinforced Concrete Shear Walls under Eccentric Tensile Axial Force

Six reinforced concrete shear wall models were built and tested to investigate effects of cyclic lateral loading and an eccentric tensile axial force on their shear strength behavior. The following are confirmed from this test result. When the elongation at the bottom of the boundary column on the compression side for a lateral force is small, the shear strength of shear walls subjected to a tensile axial force at the boundary column can be evaluated by conventional shear strenght equations, regardless of cycilc lateral loading and the eccentric tensile axial force. However when this elongation of the boundary column increases, the test maximum value is much lower than the value calculated from conventional equations

Strength Behavior of High Strength R/C Columns under Biaxial Bending-Shear and Varying Axial Load

Twelve short square R/C columns using high-strength concrete were tested to examine the effects of biaxial bending-shear force and varying axial load on the shear and flexural strength behavior. The columns were cyclically deflected either along their transverse principal axis to produce uniaxial bending-shear or along their diagonal to produce biaxial bending-shear. For columns failing in flexure, the experimental results were found to be in close agreement with the computed values given by the AIJ Code, regardless of the differences of concrete strength, biaxial bending-shear and varying axial load. For short columns subjected to low compressive or tensile axial stress, the computed ultimate shear strengths by the 1988 AIJ Design Equation overestimated the test results. The shear test results were in best agreement with the computed values by the "Kuramoto-Minami\u27s Ultimate Shear Design Equation" proposed in 1990

Shear Behavior of Reinforced Concrete Shear Walls under Tensile Axial Force with Eccentricity

A lateral loading test of six reinforced concrete shear walls subjected to an eccentric tensile axial force was carried out to examine their shear behavior. Next facts ware confirmed on the shear strength of the walls subjected to an eccentric tensile axial force. The test results can be evaluat by the shear strength equation [2] considering axial tensile stress. The calculated values given by the (AIJ "Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Inelastic Displacement Concept") equation [3] are a little lower than the test results

Shear Resisting Behavior of Short Reinforced Concrete Columns under Biaxial Bending-Shear and Varying Axial Load

The effect of biaxial bending-shear force reversals and varying axial load on the shear resisting behavior of short reinforced concrete columns was experimentally investigated. The short columns with square section were cyclically deflected along their principal axes and their diagonals to produce biaxial bending-shear under uniaxial loadings. The results from 10 tests were considered. It was concluded that the shear strength of short columns under varying axial load could be estimated using existing existing empirical formulae and, in case of high axial stress, the shear strength of column loaded diagonally was 5~6 % lower than that of the column loaded along the principal axis

Identification of cell cycle–arrested quiescent osteoclast precursors in vivo

Osteoclasts are multinucleated cells that resorb bone. Although osteoclasts originate from the monocyte/macrophage lineage, osteoclast precursors are not well characterized in vivo. The relationship between proliferation and differentiation of osteoclast precursors is examined in this study using murine macrophage cultures treated with macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB (RANK) ligand (RANKL). Cell cycle–arrested quiescent osteoclast precursors (QuOPs) were identified as the committed osteoclast precursors in vitro. In vivo experiments show that QuOPs survive for several weeks and differentiate into osteoclasts in response to M-CSF and RANKL. Administration of 5-fluorouracil to mice induces myelosuppression, but QuOPs survive and differentiate into osteoclasts in response to an active vitamin D3 analogue given to those mice. Mononuclear cells expressing c-Fms and RANK but not Ki67 are detected along bone surfaces in the vicinity of osteoblasts in RANKL-deficient mice. These results suggest that QuOPs preexist at the site of osteoclastogenesis and that osteoblasts are important for maintenance of QuOPs

Shear strength and cracking behavior of reinforced concrete nonstructural walls

Recent Japanese earthquakes have severely damaged the nonstructural walls of many buildings. While nonstructural walls do not influence the seismic performance of a building, this damage can still sometimes cause buildings to be demolished or render their continued use impossible. Therefore, it is important that seismic designs take the seismic properties of nonstructural walls into consideration. Shear loading tests and FE analysis were conducted to investigate this phenomenon, which showed that shear strength decreased and crack width increased with wider rebar spacing. The FE analysis indicated that the discrete crack model evaluated the test results more adequately than the smeared crack model. In addition, the stress distribution was localized with wider rebar spacing. Therefore, it is thought that the shear strength decreased. Finally, a simple crack width prediction method was proposed. With this method, the rebar strain was calculated using the horizontal deformation of the walls. Using this method, the crack width could be reasonably estimated. It is believed that these findings will be useful for designing nonstructural walls with improved seismic performance

Strengthening Effect of the Fixing Method of Polypropylene Band on Unreinforced Brick Masonry in Flexural, Shear, and Torsion Behaviors

Every year, Vietnam faces typhoons accompanied by strong winds. Semi-permanent houses are severely damaged by these winds. We researched a strengthening method using a Polypropylen (PP) band to prevent housing damage caused by strong winds. In this study, we have developed a new method of fixing PP band to bricks. The PP band is sandwiched between two flat steel washers and fastened with steel screws to a plastic plug embedded in the side of the brick. A total of 49 specimens were used to study the influence of the PP band on the flexural, shear, and torsional behaviors of brick masonry. In the flexural tests, the results show that the average load-carrying capacity at ultimate failure and deflection at first crack of the PP band specimens was 1.7 and 1.62 times, respectively, higher than those of non-PP band specimens. In the shear tests, the tests on the strengthened specimens showed an increase in the shear strength for all pre-compression ranges of 0.2–0.6 N/mm2. However, it was not significant. Similarly, the initial stiffness was not significantly affected by the pre-compression level in both the reinforced and unreinforced cases. In the torsion tests, the improvements in the average load-carrying capacity and deformation ability at the first crack were 1.21 times and 1.47 times, respectively. In the reinforced specimens, at ultimate failure, a slight increase in load was observed, but it did not exceed the initial peak load