The Effect of Suffusion Phenomenon in the Increasing of Land Subsidence Rate

Land subsidence is defined as gradually ground surface settlement in an aquifer due to the compaction of unconsolidated sedimentary deposits. Since in an aquifer, deposits consist of cohesive or non-cohesive alluvial soil layers. The consolidation theory cannot be explained as the only reason for land subsidence. According to the susceptibility of alluvial soils to suffusion, internal erosion is also considerable to enhance the rate of the local settlement. Suffusion is explained as a process of soil particle movement in the soil body due to the effect of seepage flow on it. The subsidence rate in southwest and south of Tehran in Iran is very considerable whereby some structures have suffered significant damages due to this phenomenon. In this research, the contribution of suffusion and land subsidence was investigated in damaged building located at Ghale Morghi Street in southwest of Tehran, as a case history. Because of the incapability of available methods, in this article, a probability pattern is also proposed using statistical analysis for determination the likelihood of internal instability in alluvial soils in regard to soil cohesiveness

Using Fragility Curves for the Evaluation of Seismic Improvement of Steel Moment Frames

There are numerous methods for buildings’ seismic improvement, one of which is to increase    the lateral force demand. To do so, adding different types of frames or a shear wall in structures is quite common as a new structural element. The present study selects three steel moment frame structures with four, seven, and twelve stories, all of which have similar floor plans and are designed based on the old seismic design code (UBC 1997 code), which is vulnerable in accordance with FEMA 356 code. For seismic improvement Concentrically Braced Frame (CBF), Buckling Restrained Brace (BRB), and shear wall have been used. The seismic performance level of the primary structure and improved structures were compared by means of seismic fragility curve. Earthquake intensity index is “PGA”. Finally, by selecting an appropriate damage index, fragility curves of the original structure as well as the improved structures were presented and compared with a normal log distribution, the results of which was analyzed.Bu çağlarda binalarin titreşimle iyi Olması için çoklu yollar var. Bu yollardan biri binani yan sertlikinin çok olmasıdır buna göre perde yada canlandırıcı yeni yapi elemanlari çok yaygındır. Bu çalişmada uç yapida dört,yedi,ve oniki. Katlarda çelik moment cevcevleri kalaninlmiştir ki her üç plani ortak zemindedir eski versiyonu bina titreşimi güçlendirilmiş  duzenleme (UBC 1997code) tasarlanmıştır ki FEMA 356 düzenlemesine göre binalar çok savunmasız dir ve seçilmişdir binanin titreşim gelişmesine göre CFB ve BRB ve perde bulabilmiştir sismik bina performans düzeyini ve geliştirilmiş  binalari eğer ile kirilgan olduğunu binalar karşılaşırmış. PGA deprem şiddet indeksi seçilmiştir ve sonunda sismik kırılma ayarlari uygun yaralanma şiddeti şeçilerek asil bina ve geliştirilmiş bina karşılaştırilmiş ve sonuçları araştırılmışti

Mechanical Behavior of a Mine Tailing Stabilized with a Sustainable Binder

Mining is a primary sector for the national economy of many countries, but exploiting these natural resources causes negative impacts on the environment. Tailings produced during mining, called mine tailings, have to be disposed of, and for that purpose, they are often mixed with Portland cement to control environmental toxicity and improve their mechanical properties. However, the high environmental impacts of producing Portland cement are well known. In this sense, sustainable binders based on the alkaline activation of industrial wastes have been studied as an alternative to using Portland cement. This study focused on applying a sustainable binder based on the alkaline activation of fly ash to improve the mechanical performance of a mine tailing from a mine located in Portugal. Geotechnical tests and chemical analysis were conducted to characterize the mine tailing and fly ash used in the alkaline activation process. In addition, triaxial tests were performed to evaluate the mechanical performance of the specimens, with both natural and stabilized tailings. The developed study proved that stabilized tailing with activated fly ash shows promising mechanical performance showing that this approach can be an excellent alternative to using Portland cement