To investigate the influence of corroded steel bars on seismic performance of reinforced concrete (RC) columns, eight full-scale RC columns were designed and fabricated, which were composed of one uncorroded RC column, three RC columns with longitudinal reinforcement corrosion and four stirrup-corroded RC columns. The electrochemical test was conducted to accelerate the corrosion of steel bars in RC columns, and the low-cyclic repeated loading tests on RC columns with corrosion-damaged steel bars were carried out. The seismic behavior indicators, including the hysteretic curves, skeleton curves, displacement ductility coefficient, stiffness degradation curves and energy dissipation capacity of corroded RC columns and uncorroded columns, were compared and discussed. The experimental results show that with the increase in steel bars corrosion degree, the pinch phenomenon of the hysteretic curve gradually increases, and the energy dissipation capacity, stiffness and plastic deformation capacity of specimen reduce significantly. The ductility and energy dissipation coefficient decreased by 20% and 36%, respectively, when the stirrups corrosion ratio of specimen reaches 15.2%, and a shear failure surface was formed in the plastic hinge zone at the foot of the columns, which leads to the change of failure mode from ductile bending failure to shear failure with poor ductility under the ultimate load for corroded columns. The influence of stirrup corrosion on the failure mode of specimens is remarkable, but the effect of longitudinal reinforcement corrosion is negligible for specimens with the corrosion ratio within 14.7%. The adverse effects caused by over 15.2% stirrup corrosion should be considered in seismic design of structures in seismic zone.

In this work, to further investigate the vegetation concrete technology for slope protection, a total of 10 groups mix proportion specimens of porous concrete were designed and constructed. As a result, the impacts of different parameters include the fly ash and silica fume contents on the mechanical properties and porosity as well as the pH value of porous concrete were discussed. Meanwhile, ecomodified soil with resistance to the erosion of rainwater was sprayed on the surface of porous concrete for the survival of native grass growth. In addition, the growth characteristics of the Festuca arundinacea schreb (Chinese grass) within eco-modified soil on the surface of porous concrete were observed and monitored for 8 weeks including the average height, root system development and relative coverage of grass. The results show that the compressive strength and porosity of porous concrete measured after 28 days were at least 13Mpa and 21% respectively, indicating the porous concrete is suitable for the slope protection in practical engineering. Furthermore, the integration of eco-modified soil and porous concrete was successful, and all grass survived in the eco-modified soil and porous concrete environment for the duration of the observation period, and the coverage rate of vegetation reached 96% or above. It was also found that the roots system has permeated the pores of porous concrete and reached the bottom of porous concrete after 8 weeks.

There are many horizontal joints on precast concrete (PC) wall panel structures, which certainly has a significant impact on the seismic behavior of structures. This paper proposes a novel alveolar-type horizontal joint, which has advantages of convenient and rapid assembly. Six precast concrete wall specimens with alveolar-type joints were designed and constructed, and they were weakly connected by spliced rebars anchored into grouted sleeves to meet the requirements of structural performance. The pseudo-static loading tests on these specimens were conducted to investigate the effects of influencing factors, such as the axial compression ratio, the thickness of wall (interface contact area), and the addition of a vertical grouted sleeve connection at the horizontal joint, on the seismic performance of PC walls. Analyses and comparisons were conducted in terms of the cracking propagation pattern, failure modes, force–displacement hysteretic curves, skeleton curves, bearing capacity, ductility factors, and energy dissipation of PC walls. It was concluded that the axial compression ratio and adding grouted sleeve connection had a significant influence on the cracking mode of PC walls, whereas the impact of the wall thickness was slight. The shear capacity and energy dissipation capacity of specimen dramatically enhanced by increasing the axial compression ratio or adding grouted sleeve connection. The PC wall exhibits good ductility after adding the vertical grouted sleeve connection at a horizontal joint. However, the ductility factor increases firstly and then decreases in the enhancement of the axial compression ratio. The reduction in wall thickness has remarkable impacts on the shear strength and energy dissipation capacity of specimens, but the influences on ductility were not significant. The prediction method for calculating the shear capacity of PC walls with alveolar-type horizontal joints was proposed based on the experimental data, and these calculated results are in good agreement with the experimental results.

This paper presents a type of prefabricated concrete wall panel building system with novel flexible alveolar-type joints, which has the advantages of fast assembly and controllable quality. Seven alveolar-type joint specimens were designed and fabricated to investigate the influence of the axial compression ratio, the size of the joint (in the interface contact area), and the strength of the mortar on the joints’ performance. The shear–slip constitutive model of the alveolar-type joints was established on this basis. The accuracy of the constitutive model was verified by comparing two full-scale loading tests with the exact finite element analysis model of ABAQUS. A finite element model of a multi-story apartment building was established by using the aforementioned shear–slip constitutive model; thus, the simplified analysis method for the prefabricated concrete wall panel building structure with alveolar-type joints was proposed. It was concluded that increasing the axial compression ratio, mortar strength, and size of the joints could increase the shear-bearing capacity by different degrees and that the 50 mm depth joint could increase the capacity by 18.6%. The proposed shear–slip constitutive model simulated the interface mechanism well by comparing the test results. Furthermore, the simplified analytical methods of the integral structure were in good agreement with the FEA results.

The pile foundations below approach slab in a semi-integral abutment jointless bridge (SAJB) that requires high flexibility to accommodate the horizontal cyclic deformation of approach slab generated by the girder’s thermal expansion and contraction as well as earthquake action. In this paper, reactive powder concrete (RPC) and reinforce concrete (RC) micro piles were designed and fabricated. The shaking table tests on dynamic response of micro piles-soil interaction were conducted to investigate the dynamic response characteristics such as the strain time history of pile-soil system, the bending moment, and the deformation of piles. The maximum strain response of piles was observed at the buried depth of 4.2 D (D is the diameter of pile). Meanwhile, the maximum bending moments of RPC and RC piles appear at the depth of 0.64 D and 0.42 D, respectively, under the dynamic load excitation, and the peak horizontal deformation of piles were observed at pile head. It is found that the bending moment and the strain response of the RPC pile are larger than that of the RC micro pile, and increased by 40% and 98%, respectively. The RPC micro pile has better crack resistance, higher ductility, and flexural rigidity than that of the RC pile, and it can be widely used as pile foundations in SAJBs for the earthquake area.

To improve the shear performance and construction efficiency of horizontal joints in prefabricated concrete wall panel structures, an innovative keyway joint for prefabricated concrete wall panels is presented to maximize the contact area and joint friction, enhancing both the shear performance and the installation efficiency. Shear tests on eight prefabricated concrete wall panels were conducted to investigate the effects of the axial compression ratio, interface mortar strength, and keyway depth on the shear performance of these novel joints. Concurrently, a finite element model for prefabricated concrete wall panel keyway connections was established via ABAQUS, and a parametric analysis approach was employed to study various factors such as the axial compression ratio, the interface mortar strength, and the keyway construction type, as well as their impact on the shear performance of joints. The findings showed that, as the axial compression ratio increased, the failure mode of the keyway joint transitioned from shear brittle failure to compressive shear plastic failure, accompanied by evident crack propagation. The recommended keyway depth parameter remains between 40 and 80 mm, with the inclination angle of the keyway joint ideally ranging from 0° to 20°. Compared to the straight joint, the shear capacity of the innovative keyway joint increased by 16.5%.