Journal of the Structural Engineering and Geotechnics
Volume:4 Issue: 1, Winter 2014

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran. A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total normal stress. Regarding the shear moduli and the damping ratio, due to the disturbances of the stiff deposits in the sampling process and great deviations of laboratory results from field results, the laboratory measurements of these parameters out of the above limits are not recommended.

Many existing bridges were designed without adequate consideration of seismic risk. The full or partial collapse of even one major bridge in a city or community would have destroying results. There has been focuses on developing fragility-based seismic vulnerability of existing usual bridges in Iran or support decision making on seismic upgrade. This article focuses on developing performance based seismic fragility curves for typical RC bridges in Iran. Ground motions compatible with the seismic hazard were used as input excitations for bridge vulnerability assessment. The fragility curves thus developed will quantify the vulnerability of existing RC bridges and help in proper decision making to increase the safety for humans and the serviceability of essential facilities. Results obtained from this study show that the properties of materials have a significant effect on the damage probability of the bridges. The findings can serve as a guide to declare the impact of seismic vulnerability on the bridges.

The present study examines the new generation of concrete. Concrete has long been a major problem, is its ductility. Traditionally, remembering the words of concrete, compressive strength also comes to mind. Compressive strength is not only parameter of necessary and sufficient for a material. Concrete is basically brittle material. By adding the steel in this material is an attempt to ductile it. Provide the necessary ductility, with the addition of the steel and high costs is possible. Is it possible to concrete without adding the steel to the desired ductility that desire? In the future, the studies in this regard will be discussed.

A sodium silicate-based chemical grout was used in the Karkheh dam site in order to examine the performance of the chemical grouting technique for stabilization of the dam's filter material. Karkheh, an embankment dam with the reservoir capacity of about 7.4 billion cubic meter at the maximum water level, is the largest dam in Iran. The grouting works performed at the dam site, were part of the prerequisites for development of the dam's complementary cut-off wall. Since the dam was completed, the execution of the new cut-off wall from the dam crest was inevitable. Hence, one of the main difficulties associated with the development of the new wall was trenching and execution of plastic concrete wall through filter materials of the dam body. To resolve this technical problem, the method of chemical grouting was employed. However, the process was so challenging since little research work has been devoted to the application of grouting technique in filter. Wide testing program including full scale tests were performed to obtain optimized mix design and grouting program. A full scale platform consisting actual filter materials was constructed and undergone various tests. Results of the testing program revealed that a chemical grout consisting of sodium silicate, water, and ethyl acetate with proper mix ratio can successfully stabilize the filter of the dam body.

One of the most important subjects in relation of water resources quality in the many of river is the chemical composition of waters and conservation of water quality in the watershed. Geological formations in any region of the earth are the main surface and foundation that water flows on the bed and strata of formation, which in fact they affect their characteristics on water quality as positive or negative effects. The effect of various geological formations analyzed from Pre-Cambrian to recent Era in some of region in Iran. To show their effects on water quality on a few of water rivers, and therefore to classified these formations, they divide into two separate groups; desirable and undesirable formations. It is necessary to classify them depend on their resistance against weathering and erosion. Influence of these two agents on geological formations will produce the material which effects on water quality that considered in this paper, it have been assessed and explained. There are many cases of river in different regions in Iran such as lower stream Karoon, Qezel-uzan, Qom-Rud River, and etc..., in which they passed and flow in the Neogene formations, and they have changed the water quality of rivers. It is notable that this study can be useful in river engineering, dam construction, flood spreading, rain water harvesting and transmission of water for drinking or agriculture targets.

In this study we tried to consider effect of vertical component of near zone earthquake (10 to 15 km far from fault) such as Kobe 1995, Northridge 1994, Loma prieta 1989 and Chichi 1999 on a concrete cable bridge by a 320m span in the middle which was built on different type of soils.
The SAP software (version14) was selected because I should have done linear and non-linear time history analysis by defining plastic hinges. Also we achieved to some results depended on types of soils and finally we extracted some factors for dead load to consider effect of vertical component of earthquakes on axial force, shear force and bending moment of different parts of the structure, also we gathered some results about horizontal and vertical displacement of span in the middle.