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This paper totally reports the results of 8 pure torsion tests on channel steel reinforced concrete beams (CSRCB) and one pure torsion test on normal reinforced concrete contrast beam. The variables studied were the concrete strength, the configuration form of stirrup, and the form, angle, spacing of lace bar. It is shown that the concrete strength, stirrup disposition and channel steel have significant effects on the torsional capacity of the beam after comparative analysis. The failure mode and crack patterns of test specimen are investigated, also the working mechanism of channel steel and the concrete are analyzed in this paper. Finally, a calculation formula for cracking torque and ultimate torque of CSRCB are proposed. Good agreement was demonstrated between the test results and the calculation results which indicates that the calculation formulas proposed in this paper are applicable to the calculation of cracking torque and ultimate torque of CSRCB.

This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped (SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine T-shaped SRC columns, four L-shaped SRC columns and four +-shaped SRC columns were tested to examine the effects of shape steel configuration, loading angle, axial compressive ratio and shear-span ratio on the behavior (strength, stiffness, energy dissipation, ductility, etc.) of SRCSS column specimens. The failure modes and hysteretic performance of all the specimens were obtained in the tests. Test results demonstrate that the shear-span ratio is the main parameter affecting the failure modes of SRCSS columns. The specimens with small shear-span ratio are prone to shear failure, and the primary failure planes in SRCSS columns are parallel to the loading direction. As a result, there is a symmetry between positive and negative loading directions in the hysteretic curves of the SRCSS columns. The majority of displacement ductility coefficients for all the specimens are over 3.0, so that the SRCSS columns demonstrate a better deformation capacity. In addition, the equivalent viscous damping coefficients of all the specimens are greater than 0.2, indicating that the seismic behavior of SRCSS columns is adequate. Finally, the superposition theory was used to calculate the limits of axial compressive ratio for the specimens, and it is found that the test axial compressive ratio is close to or smaller than the calculated axial compressive ratio limit.

This paper focuses on the study of seismic-induced damage assessment of three-dimensional (3D) joints connected with T-shaped steel reinforced concrete (SRC) column-steel beams. Low cyclic reversed loading tests on one planar joint and nine 3D joints were firstly conducted to intensively investigate the seismic behavior of the hybrid joint. The damage index calculation models such as the displacement-based type, energy-based type and displacement & energy-based type were discussed and applied for all the specimens according to the experimental results. In addition, the effects of shape steel configuration type, loading angle and axial compression ratio on the damage development and accumulation for test specimens were analyzed through Park-Ang model. The analysis results show that the selected parameters of damage-index calculation models have great effect on the developing trends of damage curves. Under the same ability of relative deformation, the accumulated damage of the specimens configured with T-shaped steel are much larger than that of the specimens configured with channel-shaped and solid-web steels; moreover, the degree of damage accumulation for the specimens under 30° and 60° loading angles is slightly larger than that of the specimens under 45° loading angle. The specimens subjected to a lower axial force level have a faster damage development, but the damage accumulation is smaller than that of the specimens under a higher axial compression ratio.

This paper describes a series of tests on steel tubular short columns of circular section filled with normal concrete (NA) and recycled aggregate concrete (RAC). Twenty-two specimens, including 11 small diameter of RAC-filled steel tubular (RACFST) columns named CA series and 11 larger diameter of RACFST columns called CB series, were tested to research the influence of variations in confinement index and replacement ratio of recycled coarse aggregate (RCA), from 0% to 100% with 10% increasing. The test results show that both types of RACFST columns and normal concrete-filled steel tubular (CFST) columns failed due to oblique shear pressure damage with a drum-like. Comparisons are made with predicted bearing capacities of RACFST columns using the existing theories, such as Unified Strengthen theory (I), Confinement theory (II) and Superposition theory (III). The equation for axial compression stress-strain curves of the whole process are proposed in this investigation for RACFST short columns, which can be directly used in theoretical and numerical analysis as well as practical engineering design and evaluation of RACFST structures.

External shearing connectors effectively improve the bond strength of concrete filled square steel tube (CFST), which ensures the concrete and steel tube work together properly. Based on the two CFST joint push-out tests, the influence of external connectors on the CFST bond strength was obtained. It is demonstrated that distribution of bond strength along specimen height is uneven. An increase in push-out load was due to the effect of “confinement”, “clamp” and “hoist node”. The bearing capacity equation of connectors is obtained based on literatures and experimental data. It is found that calculated results are in line with experimental data. Further attentions should be paid to this field.

In order to study the dynamic response of freestanding brick cave-dwellings, the shaking table tests were performed on a structural model with the 1/4 scale. Two natural seismic waves and one fitted artificial wave were used as the input excitation to the structure to analyze its failure modes, dynamic characteristics, acceleration response, displacement response, torsional effect, base shear, and hysteretic energy dissipation. The results show that the Yaolian, Yaotui, and the middle dome are severely damaged under an earthquake. The natural frequency of the structure decreases with the cumulative damages, while the overall damping ratio appears to increase with the cumulative damages. The structural stiffness along the depth is eccentrically distributed, which causes a noticeable torsion effect while the structure responds in unidirectional translational motion under an earthquake. Among them, the acceleration response of the back wall is smaller than that of the Yaolian under low intensity earthquakes, but the situation is reversed under higher earthquakes. As the peak ground acceleration increases, the interlayer shear force gradually reaches the ultimate bearing capacity of the structural story, causing the structural stiffness gradually degrades. Obviously, the stiffness degradation of Yaotui story is more significant than other structural stories, particularly the stiffness degradation of the middle Yaotui is greater than that of the side Yaotui, and the stiffness degradation of the middle dome constrained by the middle Yaotui is also more significant. In addition, the structural deformation and cumulative energy dissipation increase significantly with the increase of the peak ground acceleration Refereed/Peer-reviewed

Brick cave dwellings are a traditional residence widely built and used in the Loess Plateau of China, but the current understanding of their seismic performance is still scarce. In the present study, the weak areas and dynamic response characteristics of brick cave dwellings were explored by performing shake table tests on a 1:4 scaled model. The test results indicate a noticeable increase in the structural model's dynamic response and damage when the PGA (Peak Ground Acceleration) was 0.5 g, while the structural stiffness substantially degraded when the PGA reached 0.6 g. The severely damaged areas on the structural model mainly refer to the piers, middle barrel vault, and Yaolian, and the damage cracks at the wall junctions were denser in particular. Along with the PGA increases, the stiffness degradation of the pier story and roof story was higher than that of the vault story, leading to differences in the dynamic responses between the three stories. Since the flexibility and stiffness degradation of the middle piers were higher than that of the lateral piers, the vertical displacement response of the middle barrel vault constrained by the middle piers was considerably higher than that of the lateral barrel vault. When the chambers opened on the Yaolian of the brick cave dwellings and caused an eccentric distribution in structural stiffness, the dynamic responses of the Yaolian and back wall were rendered differently while a torsion effect was produced. Further analysis also showed that the accumulated hysteresis energy dissipation of each structure story was not the same, the energy dissipation by inelastic deformation increased significantly when the PGA reached 0.6 g, and the structure entered the elastoplastic stage.