International Journal of Civil Engineering最新文献

Screw piles have a greater bearing capacity than straight piles due to their larger helix. However, an excessively large helix can cause bending and reduce the soil bearing capacity. This study investigates the failure pattern and mechanical performance of screw pile helices through full-scale load tests and numerical analyses. The results revealed that the helix buckled at its connection to the shaft. Additionally, the geological characteristics of the soil in which the pile was located had a negligible effect on the mechanical properties of the helix. Furthermore, the shape of the anchor plate (flat or helical) had a negligible effect on the load-bearing properties of the pile or the mechanical properties of the anchor plate itself. To simplify the analysis, the screw pile helix was assumed to be a flat circular plate. For a uniformly loaded flat circular plate with fixed inner edges, the result of Roark’s formula satisfactorily agreed with the measured maximum radial normal stress in the helix. Moreover, the value given by Roark’s formula for a flat circular plate with simply supported inner edges agreed well with the measured helix deformation.

In the present study, a simplified finite element micro-modeling technique was developed for the in-plane cyclic lateral load analysis of reinforced concrete frames with masonry infill walls having openings. Such frames are commonly constructed in several countries, and if not constructed properly, tend to get damaged during earthquakes thereby increasing the seismic risk in the region. Results of the numerical studies showed the effectiveness of using the simplified finite element micro-model in accurately predicting their lateral load responses. A finite element parametric study was undertaken to understand the influence of size and location of openings in masonry infill walls and aspect ratio of the reinforced concrete frames on lateral load response of infilled frames. Though the aspect ratio of the frame and size of the openings were found to have a significant effect on the lateral load characteristics of the frames, such as, lateral strength, lateral stiffness, and energy dissipation capacity, the influence of location of opening on these parameters was limited. It was also observed that the contribution of masonry infills reduced significantly when size of the opening in the wall was more than 20%. Further, the influence of horizontal eccentricity in the wall openings was found to be insignificant for most of the studied frames.

In order to investigate the impacts of corrosion damage on the seismic performance of recycled aggregate concrete (RAC) columns, the hysteretic behavior of the corroded RAC columns was studied through quasistatic tests and numerical analyses. The main parameters included different corrosion ratios, axial load ratios (ALR), and stirrup ratios. The results revealed that there were no significant differences in the carrying and deformation capacities of the corroded RAC column compared with the corroded NAC column. Under electrochemical chloride erosion conditions, the corrosion ratios of stirrups were on average 44.6% higher than those of longitudinal bars, and the crack widths of columns with different corrosion ratios varied little, ranging from 0.1 to 0.5 mm. Under a relatively low corrosion ratio (within 10%), the corrosion had a minor impact on the horizontal carrying capacity, but the deformation capacity of the corroded columns decreased with increasing corrosion ratio and ALR. The coupling effect of a high ALR and a high corrosion ratio could exacerbate the detrimental impact of corrosion, and special attention should be given to columns with an ALR exceeding 0.3 and a corrosion ratio exceeding 10%. In addition, the seismic performance of the corroded structure could be effectively simulated through the finite element model based on the modified corrosion model of the materials.

Soil and pile interaction could significantly contribute to the response of the system and should be considered in the design prospect. To address some of the uncertainties, a series of 1 g shaking table tests followed by numerical simulations were conducted to address the seismic response of free-head single piles embedded in dry sand subjected to seismic waves of which horizontal acceleration and bending moments are the prime indexes. Subsequently, the validated numerical model was employed to perform parametric studies, focusing on normalized induced kinematic forces based on the soil profile type. The numerical results showed that not only does the soil profile type considerably affect the amplitudes of the maximum normalized seismic forces but also the distributions of these response parameters are highly dependent on soil type. The results also demonstrated that neglecting slippage and/or separation along the soil–pile interface leads to underestimation of the maximum normalized kinematic bending moment and shear force by up to 17.5% and 70%, respectively. Soil type also affects the induced forces by about 60% indicating that the design consequence of which could be dire. Therefore, it is concluded that the effects of slippage and/or separation can be considerable and hence, should be taken into consideration to prevent probable damages in seismic areas.

This study investigates the ground-motion analysis and local site effects in Kahramanmaras city during the 6 Feb 2023 Turkey–Syria earthquake sequence. The damage distribution was non-uniform, concentrated in an area with 8–10-story buildings on alluvial soil. Comparison between the recorded data and several ground-motion models examined in this study indicates that ground-motion models predict the spectral accelerations around 3 times less than what observed during the first event. Site response analyses are carried out for three sequential earthquakes with magnitudes greater than 6.5 occurred on 6th of February 2023. Deconvolution analysis shows that the peak ground acceleration of bedrock motions correlates with distance: 0.1 g farthest, 0.3 g nearest, and ~ 0.2 g intermediary stations in Kahramanmaras city. The results of convolution analysis indicate that the ground surface spectral acceleration of the first event is the dominant spectra compared to the second and third events for periods less than 4 s. The results of site response analysis show that the 10-story buildings tolerated a spectral acceleration upto 0.85 g which is ~ 1.8 times greater than what is recommended by the available national design spectrum (i.e., the 2007 Turkey seismic design code). This means that the recorded motions in Kahramanmaras city have return periods larger than the 475 years of the Turkish seismic design code.