2026-08-09T18:01:59+03:30 http://ijce.iust.ac.ir/browse.php?mag_id=24&slc_lang=en&sid=1

24-310 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 M.B. Javanbarg A.R. Zarrati M.R. Jalili Kh. Safavi In the present study a quasi 2-D numerical model is developed for calculating air concentration distribution in rapid flows. The model solves air continuity equation (convection diffusion equation) in the whole flow domain. This solution is then coupled with calculations of the free surface in which air content in the flow is also considered. To verify the model, its results are compared with an analytical solution as well as a 2-D, numerical model and close agreement was achieved. The model results were also compared with experimental data. This comparison showed that the decrease in air concentration near the channel bed in an aerated flow could be well predicted by the model. The present simple numerical model could therefore be used for engineering purposes. High speed flow Cavitation Aeration Numerical model Air concentration. 2007 3 01 1 13 http://ijce.iust.ac.ir/article-1-310-en.pdf

24-311 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 M. Khanzadi G. Ghodrati Amiri G. Abdollahzadeh Darzi According to performance-based seismic design method by using energy concept, in this paper it is tried to investigate the duration and damping effects on elastic input energy due to strong ground motions. Based on reliable Iranian earthquake records in four types of soils, structures were analyzed and equivalent velocity spectra were computed by using input energy. These spectra were normalized with respect to PGA and were drawn for different durations, damping ratios and soil types and then effects of these parameters were investigated on these spectra. Finally it was concluded that in average for different soil types when the duration of ground motions increases, the input energy to structure increases too. Also it was observed that input energy to structures in soft soils is larger than that for stiff soils and with increasing the stiffness of the earthquake record soil type, the input energy decreases. But damping effect on input energy is not very considerable and input energy to structure with damping ratio about 5% has the minimum value. PGA; duration of strong ground motion; damping ratio; input energy spectrum. 2007 3 01 14 29 http://ijce.iust.ac.ir/article-1-311-en.pdf

24-312 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 Ali Kheyroddin Hosein Naderpour A parametric study is performed to assess the influence of the tension reinforcement index, ( ω = ρ fy /f Bc), and the bending moment distribution (loading type) on the ultimate deformation characteristics of reinforced concrete (RC) beams. The analytical results for 15 simply supported beams with different amounts of tension reinforcement ratio under three different loading conditions are presented and compared with the predictions of the various formulations and the experimental data, where available. The plastic hinge rotation capacity increases as the loading is changed from the concentrated load at the middle to the third-point loading, and it is a maximum for the case of the uniformly distributed load. The effect of the loading type on the plastic rotation capacity of the heavily reinforced beams is not as significant as that for the lightly reinforced beams. Based on the analytical results obtained using the nonlinear finite element method, new simple equations as a function of the tension reinforcement index, ω, and the loading type are proposed. The analytical results indicate that the proposed equations can be used for analysis of ultimate capacity and the associated deformations of RC beams with sufficient accuracy. Nonlinear Analysis Finite Element Plastic Hinge Reinforced Concrete Rotation Capacity 2007 3 01 30 47 http://ijce.iust.ac.ir/article-1-312-en.pdf

24-313 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 A.A. Khosroshahi S.A. Sadrnejad A framework for development of constitutive models including damage progress, based on semi-micromechanical aspects of plasticity is proposed for concrete. The model uses sub-loading surface with multilaminate framework to provide kinematics and isotropic hardening/softening in the ascending/descending branches of loading and can be able to keep stress/stain paths histories for each plane separately. State of stresses on planes is divided to four basic stress patterns i.e. pure compression, increasing compression-and shear, decreasing compression-shear and tension-shear and used in derivation of plasticity equations. Under this kind of categorized form the model is capable of predicting behavior of concrete under any stress/strain path such as uniaxial, biaxial and triaxial in the monotonic and cyclic loading, Also this model is capable of predicting the effects of principal stress/strain axes rotations and consequent plastic flow and has the potential to simulate the behavior of material with anisotropy, fabric pattern, slip/weak planes and crack opening/closing. The material parameters of model are calibrated by optimum fitting of the basic test data available in the literature. The model results under both monotonic and cyclic loading have been compared with experimental results to show capability of model. 2007 3 01 48 65 http://ijce.iust.ac.ir/article-1-313-en.pdf

24-314 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 M. Heidarzadeh A.A. Mirghasemi S. Etemadzadeh A new chemical grouting method has been developed for conglomerate formations based on the experimental studies. Due to the lack of chemical grouting experience of conglomerate formations, the testing programs were performed to evaluate the performance of chemical grouting in the water sealing of part of conglomerate foundation of Karkheh earth dam using a combination of field and laboratory tests. First, the chemical grouts alone were examined with regard to viscosity-time behavior, gelation time, temperature-influence, stability, and deformability. These laboratory tests, led to the selection of the final chemical grout which was a solution of sodium silicate, water, and ethyl acetate as reactant. The second step tested grout-soil interaction: The injectability and permeability reduction of the selected chemical grout was examined in field injection tests. In this step two field tests were performed including shallow test holes without hydrostatic pressure and full scale tests under dam real hydrostatic pressure head. Based on these two field injection tests, performed in the conglomerate foundation of Karkheh dam, a new chemical grouting method for conglomerate formations is proposed and satisfactory results led to the recommendation of this method for eventually successful application. Chemical Grouting Conglomerate Formations Sodium Silicate. 2007 3 01 66 83 http://ijce.iust.ac.ir/article-1-314-en.pdf

24-315 2026-08-09 10.1002

International Journal of Civil Engineering IJCE 1735-0522 2283-3874 2007 5 1 A. Yeganeh Bakhtiary A. Ghaheri R. Valipour Determination of allowable free span length plays a crucial role in design of offshore pipelines. The seabed intervention cost and safety of an offshore pipelines project are largely influenced by pipelines free spanning during the project life time. Different criteria are proposed by both the current designing guidelines and researchers there is however lack of comprehensive assessment of independent parameters affects the design length of free span. In this note, it is intended to investigate the effects of seabed formation along with axial force on Natural Frequency of offshore pipelines. Based on this assessment a new simple formula is proposed. Finally, to evaluate the result of this study, the allowable free span length of Qeshem Island pipelines is calculated as a case study and compared with those of the DNV (1998) and ABS (2001) guidelines and the modal analysis. Offshore pipelines free spanning allowable length modal analysis and pipe resonance 2007 3 01 84 91 http://ijce.iust.ac.ir/article-1-315-en.pdf