Cushioned pile-raft foundation (Cushioned-PR) is a new type of foundation for sea-crossing bridges in deep water (more than 50 m in depth). Cushioned-PR is able to tolerate a certain amount of slide ...that occurs between the raft and the piles under strong earthquakes. This characteristic could reduce the seismic motion transmitted to the superstructure to maintain the integrity of the bridge. Thus, Cushioned-PR has become popular for bridges under the threat of strong earthquakes. However, the dynamic responses of the Cushioned-PR under various earthquake intensities in soft clay have not been thoroughly understood. It is essential to better evaluate the isolation effect of Cushioned-PR to improve the design. In this study, the non-linear behavior of Cushioned-PR and the isolation effect of its interposed layer are evaluated using centrifuge tests. A series of dynamic centrifuge tests are performed with a 3 × 3 pile group foundation embedded in soft clay under different earthquake motions. Both the cushioned pile raft foundation system (Cushioned-PR) and the connected pile raft foundation system (Connected-PR) are tested in the centrifuge tests. Acceleration and residual displacement of the super-structure, and bending moment of columns and piles, are monitored during the experiments. The results show that the interposed layer in Cushioned-PR has a significant impact on the bending moment and residual displacement of the pile-raft system. Based on the observation from this study, the maximum bending moment of the column in the Cushioned-PR is around 28%–54% of the values from the Connected-PR. On the other side, the maximum horizontal displacement of Cushioned-PR is about 2–10 times larger than that of the Connected-PR. The results show that Cushioned-PR can effectively reduce the seismic excitation transmitted to the super-structure if the seismic intensity is high. However, the benefit of Cushioned-PR is marginal under low-intensity earthquakes.
•Centrifuge tests were performed for the seismic isolation effect of Cushioned-PR on earthquake.•The isolation effect of Cushioned-PR becomes significant with the increase in the magnitude of the earthquake load.•The interposed layer has a significant impact on the propagation of inertial loading and interaction between soil and piles.•The nonlinear performance and the isolation effect mechanism of Cushioned-PR are investigated.
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GEOZS, IJS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZAGLJ
•A method is proposed to minimize the analytical process.•The peaks acceleration were considered as benchmark.•The factors for assessing the displacement of single pile were evaluated.•The ...statistical models were applied to evaluate the results.•Proposed method accelerates decision-making in single pile seismic design.
In the construction industry, pile uses to enhance seismic stability of infrastructure and tower, if the soil faces insufficient bearing capacity and unallowable nonlinear lateral and vertical displacements. In this study, I assume that the nonlinear lateral displacement mechanism and its prediction were analyzed and developed based on the non-linear seismic load. (i) The nature of seismic load, (ii) length of pile, and (iii) soil elastic modulus become model parameters to assess the nonlinear lateral displacement and vibration mechanism of a single pile. In analytical processes, instead of using the whole seismic load for calculation nonlinear lateral displacement of the pile, a method was suggested for minimization of the analytical process. The statistical models and analysis have been applied for evaluating the accuracy of the analytical results and monitoring distribution probability of nonlinear lateral displacement of pile concerning different factors. The results illustrate the effect of the directions of seismic load, more specifically their combination, as it provides the non-linearity nature of seismic load, length of pile, and soil elastic modulus govern nonlinear lateral displacement mechanism and, these factors are important for predicting nonlinear displacement and monitoring mechanism vibration of the pile. The suggested method minimizes the analytical process, provides acceptable single pile seismic response prediction, and enhances the accuracy of the analytical results. The presented method can apply to solve many nonlinear dynamics problems, and it is not limited to single pile seismic analysis and design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Within the scope of literature, the influence of openings within the infill walls that are bounded by a reinforced concrete frame and excited by seismic drift forces in both in- and out-of-plane ...direction is still uncharted. Therefore, a 3D micromodel was developed and calibrated thereafter, to gain more insight in the topic. The micromodels were calibrated against their equivalent physical test specimens of in-plane, out-of-plane drift driven tests on frames with and without infill walls and openings, as well as out-of-plane bend test of masonry walls. Micromodels were rectified based on their behavior and damage states. As a result of the calibration process, it was found that micromodels were sensitive and insensitive to various parameters, regarding the model’s behavior and computational stability. It was found that, even within the same material model, some parameters had more effects when attributed to concrete rather than on masonry. Generally, the in-plane behavior of infilled frames was found to be largely governed by the interface material model. The out-of-plane masonry wall simulations were governed by the tensile strength of both the interface and masonry material model. Yet, the out-of-plane drift driven test was governed by the concrete material properties.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The axial capacity and pile transference of loads under static loading have both been well reported, but further research is needed to understand the dynamic lateral responses. The pile load imposed ...during an earthquake may increase, but the soil’s ability to support it may fall as a side effect of the vibration leading to more settlement. The key objective of this work is to identify what led to the substantial lateral destruction of the piles during the seismic event due to the kinematic effects. These failures were related to discontinuities in the subsoil as a result of sudden changes in soil strength due to shaking. The kinematic stresses exerted in a single pipe pile constructed in two sand layers under two different situations (dry and saturated states) are investigated in this study using numerical modeling. The bending moments were higher in the saturated sand soil than in the dry one which may be attributed to liquefaction. Generally, the acceleration increased through the loose layer (from bottom to top), and then significantly settled within the dense layer. It could be shown that using this modeling, one can estimate how a pile foundation will behave under "kinematic" loading driven by earthquakes. Therefore, the design and installation of drilled aluminum or steel piles in sand soil could make use of these present observations.
Purbalingga is regency with a potential moderately high seismicity requiring compliance of planning and implementation rules of the earthquake-resistant structural system. The purpose of this ...research is to evaluate the performance of a ten-story irregular apartment building model in Purbalingga due to the seismic load. The study is necessarily conducted to provide information on impacts and mitigation strategies that should be implemented. This research was conducted based on the seismic capacity of 2002 and 2012 Indonesian National Standard (SNI) including linear static analysis, dynamic response analysis, and pushover analysis. Based on the direct static review, it shows that the base shear is reduced and the drift ratio level decreases respectively for X and Y direction.Meanwhile, based on the dynamic response analysis, the drift ratio level also decreases respectively for X and Y direction. Also, the pushover analysis indicates that the performance of this apartment building model is still at Immediate Occupancy (IO) level as the post-earthquake damage state that remains safe to occupy, essentially retains the pre-earthquake design strength and stiffness of the structure. The risk of life-threatening injury as a result of structural damage is very low, and although some minor structural repairs may be appropriate, these would generally not be required before occupancy
•Results from eight full-scale quasi-static cyclic test on GFRP- and hybrid-RC columns are presented.•Effect of longitudinal and transverse reinforcement on column behavior is discussed.•Seismic ...parameters such as ductility and energy dissipation are assessed.•The effect of confined concrete strength on lateral load capacity prediction is evaluated.
This paper reports the comparative results of an experimental study performed on concrete columns reinforced entirely with glass fiber-reinforced polymer (GFRP) bars and with hybrid reinforcement (longitudinal steel bars and transverse GFRP spirals and cross ties) subjected to quasi-static cycling loading. Four full-scale bridge columns were constructed with longitudinal steel bars and confined with GFRP spirals and cross ties (hybrid-reinforced concrete columns). Four other columns were constructed solely with GFRP reinforcement (GFRP-reinforced concrete columns). The bridge columns had a cross section of 400 × 400 mm with a total height of 1850 mm. The columns were tested to failure under combined constant compressive axial load and quasi-static reversed lateral loading. The columns were investigated in terms of longitudinal bar type, longitudinal reinforcement ratio, and transverse reinforcement ratio. The results show that the longitudinal reinforcement type significantly affected column performance in terms of seismic parameters such as ductility and energy dissipation. The hybrid-reinforced concrete columns exhibited superior ductility and dissipated more energy than the GFRP-reinforced concrete columns. Furthermore, the GFRP-reinforced concrete columns experienced more gradual failure than the hybrid-reinforced concrete columns. Appropriately confined hybrid-reinforced concrete columns attained acceptable drift levels that meet the recommendations in most design codes. The transverse reinforcement ratio and longitudinal reinforcement ratio patently influenced column behavior. The lower elastic modulus of the GFRP bars compared to that of the steel bars had an impact on the theoretical lateral load capacity of the concrete columns.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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