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Showing 23 results for Cement
Investigating the seismic performance of asymmetric multi-story buildings designed based on the ASCE/SEI 07-22 seismic code using incremental nonlinear dynamic analysis
Armin Aziminejad, Omid Makhdoom, Panan Zarfam, Abolreza Sarvghad Moghadam,
Volume 16, Issue 3 (12-2022)
Abstract
In most current seismic codes, the stiffness and strength of seismic members are considered to be independent, so that a change in the strength of the members does not result in a change in the stiffness of the members. Recent studies show that these parameters are interdependent. Therefore, the way these parameters are calculated and the arrangement of centers of mass, stiffness and strength can be effective in determining the seismic response. In this research, buildings with different levels of normalized yield eccentricity (ed/A) were designed according to the ASCE/SEI 07-22 seismic code (Code Design models) and compared with the Balance-25% and Symmetric Strength models. The results of the nonlinear static analysis and incremental dynamic analysis showed that the average spectral acceleration at the level of collapse in the Balance-25% and Symmetric Strength models increased by approximately 18% compared to the Code Design model. Therefore, these models are safer than the Code Design model. In addition, the average of the peak rotation of floors and the maximum inter-story drift at the collapse level in the Balance-25% and Symmetric Strength models has decreased by 100% and 12% respectively compared to the Code Design model. Therefore, the Code Design model had the lowest and the Balance-25% and Symmetric Strength models had the highest dynamic seismic performance.
 

Development of a Model for Predicting Elastic Modulus in the Alluvial Deposits of Mashhad Plain Using Basic Soil Parameters
Mr. Mehdi Abbasi, Prof. Gholamreza Lashkaripour, Prof. Naser Hafezi Moghaddas, Dr. Hossein Sadeghi,
Volume 19, Issue 1 (6-2025)
Abstract
The elastic modulus is considered one of the most essential parameters in the analysing and designing deep foundations and underground structures. Accurate determination of this parameter usually requires expensive and time-consuming in-situ testing, and validating its accuracy poses significant challenges. Therefore, researchers have consistently focused on developing  empirical models based on geotechnical parameters. In the present study, multiple linear regression models, including general, coarse-grained soil, and fine-grained soil models, were developed to predict the elastic modulus using data obtained from 180 boreholes totaling 5,783 meters in the Mashhad Metro Line 3 project.. Out of 489 pressuremeter tests, 160 datasets were selected based on the availability of complete geotechnical parameters at the same depth. The analysis incorporated the influence of various parameters, including the percentage of sand, silt, and fine particles; grain size characteristics (D10, D30, D60, uniformity coefficient, and coefficient of curvature); Atterberg limits; moisture content; natural and dry density; specific gravity; and cementation indicators (gypsum, carbonate, and organic matter), as well as depth and in-situ stress. The final regression models were developed using a backward stepwise method, implemented through Python programming. The resulting regression equations were derived, and comparative plots between predicted and actual elastic modulus values were presented. The findings demonstrate that the proposed model offers reliable accuracy in estimating the elastic modulus. To evaluate the accuracy of the proposed models in predicting soil elastic modulus, an independent dataset of 39 pressuremeter test results, including both fine- and coarse-grained soils, was used. Statistical indicators demonstrated that the overall model performed best (R²=0.79, MAPE=9.86%). Additionally, the low values of normalized RMSE confirmed the stability and acceptable accuracy of all models.

Evaluation of Cement Performance in Urmia Lake Basin Stabilizing Saline Soils
Ms Solmaz Darsanj, Dr. Mehrdad Emami Tabrizi, Dr. Hassan Afshin,
Volume 19, Issue 6 (12-2025)
Abstract

Aeolian sands in arid and semi-arid regions are considered problematic soils due to their loose structure, low bearing capacity, and difficult compaction. The dry climatic conditions of Iran and phenomena such as the desiccation of Lake Urmia have intensified the dispersion of saline sands. One of the common approaches to mitigate these issues is chemical stabilization using additives such as cement. This study investigates the effect of stabilizing saline aeolian sands collected from the Lake Urmia basin using Type I Portland cement. Stabilized soil specimens were prepared with varying levels of salinity and different cement contents, and were subjected to unconfined compressive strength testing after a curing period of 7 days. The results demonstrated that increasing the cement content significantly enhances compressive strength. Moreover, the presence of salt in the studied soil did not hinder the stabilization process; instead, it contributed to improved strength in the short term. These findings underscore the importance of considering both the type and concentration of salts when designing stabilization treatments for saline granular soils in arid and semi-arid climates.

 

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