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العنوان
The Effect of Soil Structural Interaction on Evaluation of Seismic
Response Reduction Factor of Multi-Story Concrete Buildings /
المؤلف
Ali, Abdel-Rhman Salama Abdel-Hamid.
هيئة الاعداد
باحث / عبدالرحمن سلامة عبدالحميد علي
مشرف / محمد نور الدين سعد فايد
مناقش / هالة محمد جمال الدين القاضى
مناقش / أحمد عبد المنعم قرشى
تاريخ النشر
2022.
عدد الصفحات
208 P. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الهندسة المدنية والإنشائية
تاريخ الإجازة
1/1/2022
مكان الإجازة
جامعة عين شمس - كلية الهندسة - قسم الهندسة الانشائية
الفهرس
Only 14 pages are availabe for public view

from 208

from 208

Abstract

The present study presents extensive research on studying the effect of SSI on evaluating the response modification factor of the multi-story frame with different types of supports such as fixed support, spring support and isolated footings with ks modulus. The following subjects are included in the work:
1) An investigation has been carried out for three models. First, a one-span, two-story reinforced concrete frame which is experimentally tested by (Vecchio and Emara 1992) and verified numerically by (Guner 2008), has been modeled using SAP2000 software. Second and three, two different 2D RC moment resisting frames consist of 4 and 8 stories are selected as reference structures and are modeled using the (CSI SAP 2000) software package with different types of supports such as fixed support, spring support and isolated footings with ks modulus.
2) An investigation has been also carried out for the effect of different four variables; soil types (Type C and Type D), seismic zone intensity (0.15g and 0.25g), spectrum types (SP1 and SP2) and support types (fixed support, spring support and isolated footing with the modulus of subgrade reaction (ks), on the seismic design of the structural elements resisting the lateral loads.
3) The study has investigating the effect of different four variables: soil types (Type C and Type D), seismic zone intensity (0.15g and 0.25g), spectrum types (SP1 and SP2) and support types (fixed support, spring support and isolated footing with the modulus of subgrade reaction (ks), on the fundamental natural period of the structures (T).
4) The study has plotted the pushover curve for the studies building
5) The present study suggests properly rational values of the response reduction factor for the analyzed multi-story buildings when taking the soil structural interaction, based on the analysis results, to be considered in the Egyptian Design Code.
6.2 CONCLUSION
The impacts of SSI on the seismic performance of 3D RC moment-resisting frames include: -
1. In terms of internal forces, the models of SSI; spring supports models and isolated footing models with Ks modulus, affects the structure of internal forces such as bending moment and axial forces, which alters the structural element’s plastic hinge development.
2. A change in soil characteristics affects the seismic performance of buildings, with taller structures and softer soil profiles seeing alterations that are more substantial.
3. The SSI effects should be addressed while evaluating the performance of RC structures, particularly when they are built on soft soils. Furthermore, it is determined that estimating the total performance of buildings based just on the performance of some specific structural components may be misleading.
4. Seismic reactions of all structural elements should be evaluated, particularly for all ground conditions, to more precisely predict the seismic performance of structures.
5. For the studied cases 3, 6, and 9 buildings, the maximum reduction in R due to considering SSI has reached 16% in loose soils. The percentage of reduction in Vu max because of taking into account SSI in loose soils is within 12%. The percentage of reduction in Vd as a result of taking into account SSI in loose soils is within 10%.
Response reduction factor (R) of RC limited ductility framed buildings: -
1. The response reduction factor is considerably affected by the seismic zone and fundamental time period of the structure. It reduces as the seismic zone increases and increases as the fundamental time period increases.
2. The given value of R-factor at ECP-201(2012) equals 5.0 for limited ductility class of reinforced concrete moment frame structures is un-conservative value at the case study for 9 stories with different types of soil, seismic zone intensity and spectrum types but it is more-conservative value at the case study for 3 stories with different types of soil, seismic zone intensity and spectrum types.
3. Recommended value of response reduction factor R for limited ductility class of limited ductility reinforced concrete moment frame structures in ECP-201(2012) is 3.9 for multi-story multi-bay frames.
4. It may be noted that Eurocode-8 (2004) specify values response reduction factor range between 3.0 and 3.9 for medium ductility reinforced concrete moment frames according to the frame configuration (multi-story multi-bay frames). UBC 97 and IBC 2012 identify for RC ordinary frame buildings response reduction factor 3.5 and 3.0 respectively.
6.3 RECOMMENDATION FOR FUTURE RESEARCH
from the numerical analyses presented in this thesis, several ideas for possible study expansions have been made to investigate the following:
1- Perform the study using time history analysis;
2- Perform the study with increasing number of stories;
3- Perform the study using Shear wall system;
4- Study other types of soil such as clay; and/or
5- Perform the study using the third method from FEMA 2020