Journal of the Structural Engineering and Geotechnics
Volume:4 Issue: 2, Spring 2014

Excess pore pressure under seismic loadings has always been a main concern in geotechnical engineering practices. Undergoing the phenomenon in a soil can cause the effective stress and hence the shear strength of the soil to decrease considerably and large deformations happen in the area. Generally, increasing the pore pressure occurs under the undrained condition. If it can be formed the drain conditions, its consequences decreases seriously. The damages caused by Excess pore pressure are divided in to two groups, surface damages and underground structures damages. Generally, first case is visible after the seismic loadings about which wide researches have been carried out. But in the second group, the lack of these occurrences and investigation problems cause the underground structures damages to be assessed less. There are several reports on devastations caused by excess pore pressure in the surrounding soil of the underground structures. As stresses and deformations of the tunnel lining increase, the surrounding soil of the tunnel is liquefied and large deformations are observed in the area. And if increasing the pore pressure occurs in the surrounding soil of the tunnel, improvement of the surrounding area of the tunnel, the stresses and deformations should be controlled to be set on the allowable limit. Therefore, evaluation of excess pore pressure effects on the tunnel lining can be regarded as an important issue. This paper is designed to focus on the topic.

Hybrid moment frame come together with reinforced concrete columns with structural steel beams (RCS). This Composite system provides several key advantages over current steel or concrete moment resisting frame. Past studies have shown this system to be efficient in both design and building stage while able to keep sufficient strength and necessary ductility in seismic zone.Although past researches controlled use of this composite structural system in the United States for none and low-seismic hazard zones, this paper considers some of the latest provisions on RCS systems, which is to provide support in the development of performance based earthquake engineering. Also paper introduces a type of rigid steel beam to RC column connection and discusses its hysteresis curvature behavior and response modification coefficient of this hybrid system.

Numerical modeling was carried out to investigate the responses of suction bucket foundations under vertical cyclic loading. Numerical results were compared with centrifuge experiment results. Before the capacity of the model suction bucket to resist cyclic loading could be investigated, the static pullout capacities had to be determined. The buckets with different aspect ratio are investigated under static and cyclic loading. In the constant diameter by increasing aspect ratio the cyclic bearing capacity will be increased and the slope of graph (cyclic bearing capacity versus aspect ratio) becomes greater by increasing diameter. Under cyclic loading, the uplift capacity of the bucket was found to be 60–76% of the monotonic capacity. It is shown that when the loading amplitude is over a critical value, the sand at the upper part around the bucket is softened. Large settlements of the bucket and the sand layer around the bucket are induced by cyclic loading.

The water supply is the crucial problem of human beings in the world. Earth dams are usually the most important structures to store and manage the main sources: surface waters. The safety of earth dams in different conditions especially under earthquake loadings plays a vital role in sustainable developments. Recently, mixed-clay soil is widely used as water- seal material in the core of earth dams, while limited studies on their seismic behaviors have been carried out so far.
This paper discusses about the displacement performance of the Karkhe Large Embankment Dam with mixed- clay core , recently constructed in south-western part of Iran , under earthquake motions and compares the dynamic analyses’ results with those of pure-clay core. In this study, the Karkhe Dam with both mixed and pure clay core is numerically modeled using the FLAC 4.0 software. After calibrating the model and completing the static and dynamic analyses under proper strong motions, selected based on the previous seismological studies, the results, including the maximum settlements, horizontal displacements of upstream and downstream shells under different excitations are compared and discussed.
Based on the obtained results, it is noted that the dynamic performance of earth dams with mixed-clay core is more desirable than that of pure-clay core. It is also observed that the seismic settlements of the dam with pure-clay core averagely show an increase of 20 percents compared with that having the mixed-clay core.

The prevention of environmental damage in durable unsymmetrical huge-capacitor (UHC) with α-MnO2 nanotubes and amorphous Fe2O3 nanotubes grown on flexible carbon fabric is first designed and fabricated. The assembled novel flexible UHC device with an extended operating voltage window of 1.6 V exhibits excellent performance such as a high energy density of 0.55 mWh/cm3 and good rate capability. The UHC devices can find numerous applications as effective power sources, such as powering color-switchable sun glasses and smart windows.