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Shake-table tests of a 3-story reinforced concrete building with cladding casted to be monolithic with frame elements, with seismic slits or cut reinforcing bars present in some cladding elements t...

Evaluating the performance of reinforced concrete (RC) structures during earthquakes and the resultant damage in the structures depends on an accurate load–displacement relationship. Several experimental and analytical evaluation methods for load–displacement relationships have been proposed and specified in current design standards. However, there have been few quantitative studies on the impact of drying on the yielding behavior of RC members, including evaluations of the effective stiffness of members. In this study, to investigate changes in the mechanical properties of RC beam–slab members due to drying of the concrete, cyclic loading tests are conducted on two RC beam–slab members with and without drying. It is found that the lateral structural stiffness of the specimen with drying decreased to 77% that of the specimen without drying. This is verified in the calculation of the flexural stiffness. In this calculation, it is assumed that drying shrinkage decreases the moment of inertia of the slab in tension but not in compression. Meanwhile, no difference is observed in the flexural capacity and yield displacement between the two specimens. Thus, there is no significant impact from drying shrinkage in RC beam–slab members on the lateral structural performance, while the shrinkage instead induces greater flexural cracking, which reduces the residual stresses in the specimen with drift leading to a gradual decrease in the impact of drying.

Formulas used to predict shear strength of reinforced concrete in different standards do not always correspond to each other due to the complexity of the shear transfer mechanism. Currently there is no generally accepted method of shear strength pridiction, however, traditionally, shear strength anticipation of a structural concrete elements is performed differently on members with or without shear reinforcement. These empirical approches tend to predict the shear strength too conservatively; alternatively, shear strength of concrete can be easily predicted by Mohr-Coulomb theory. In case of high-axial load and low shear reinforcement, the strength is likely to be determined by the concrete's shear crack. Therefore, a method to predict the strength of concrete with Mohr-circle has been proposed but the circles crossed the boundary and could not evaluate the strength correctly. Mohr circle can be used for prediction of diagonal tension failure strength but the circle cannot be evaluated. In this paper, Mohr circles were investigated considering all steps of cyclic loading until shear crack occurred. It also investigates a correlation between shear strength and normal strength through recognition of the Mohr-Coulomb failure criteria for each specimen.

Microtremor measurements are conducted in the historical area of Bagan, Myanmar, which was damaged by the 2016 Chauk earthquake, in order to analyze the site responses in the affected area. Shear wave velocity structures at the observation sites are estimated by inversion analysis of the microtremor horizontal-to-vertical spectral ratios based on the diffuse field assumption considering the results of existing seismic refraction surveys. The seismic response analysis is performed in order to estimate ground motion intensities in the Bagan area during the 2016 earthquake using the seismic observation record obtained at Nyaung-U and the estimated Vs structures. The present study reveals the pattern of the ground motion intensities during the earthquake and shows that the peak ground accelerations vary approximately 90–170 cm/s2 in the affected area. We also found no remarkable dependence of the ground motion intensity and the reinforcement after the 1975 earthquake on the monument damage grade.

The slip behavior which damage concrete and deteriorate the performance of strength and ductility can be yielded on multi-story shear wall (MSSW) after flexural yielding under cyclic loading. This paper studied the mechanism of slip behavior on MSSW under cyclic loading after the flexural yielding by conducting experimental tests using column-shaped wall. Five specimens which were scaled models of 7-story MSSW were designed preceding flexural yielding. The parameters of specimens are axial load and arrangement of bond character of the main bars at the bottom of wall. The test results show that (1) in case that the axial force is zero, the slip behavior after the flexural yielding was occurred easily, (2) the result that the slip behavior after the flexural yielding can be controlled by increasing the axial load was verified, (3) the effectiveness of steel cylinders for stopping (controlling) slip behavior is also verified, (4) a method to estimate the stiffness and displacement on the slip behavior were presented; however, crushing of concrete at the bottom of wall should be considered by reinforcing.

The shear failure of reinforced concrete shear wall brought by diagonal strut inside of wall panel can be classified into two types regardless of before or after flexural yielding: 1) shear failure of wall panel; and 2) compression failure of concrete at the bottom of boundary column. In reinforced concrete shear wall, transition of neutral axis which has greatly effects on the shear strength under plastic deformation is not considered in evaluation of deformation capacity on present standards. This paper presented a method to evaluate the deformation capacity of reinforced concrete shear walls considering failure mode based on following assumptions: 1) area of compression field is being reduced in accordance with increasing plastic deformation; and 2) shear failure occurs when the stress of the compression field reaches to the compressive strength of concrete at the wall panel or boundary column. The presented method was verified by applying to 33 test results; however, evaluation of confined effect by the boundary columns and ultimate strain of concrete should be considered.

A procedure is presented to predict the storey where plastic drift dominates in two-storey buildings under strong ground motion. The procedure utilizes the yield strength and the mass of each storey as well as the peak ground acceleration. The procedure is based on two different assumptions: (1) the seismic force distribution is of inverted triangular form and (2) the rigid-plastic model represents the system. The first and the second assumptions, respectively, lead to lower and upper estimates of the base shear coefficient under which the drift of the first storey exceeds that of the second storey. The efficiency of the procedure is verified by dynamic response analyses using elasto-plastic model. Copyright © 2008 John Wiley & Sons, Ltd.