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EngrJunaid last won the day on January 15

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About EngrJunaid

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    UET Lahore
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    Structural Engineering Solutions
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    Design of Structures

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  1. (1). Structure Aspect Ratios The Horizontal/plan aspect ratio (Length to Width ratio) of the side block is 160/18=8.8 While its vertical/slenderness ratio (height to width ratio) is 60/18=3.33 I didn't come across any code limitations regarding these ratios But an indian research paper "Effect of Aspect Ratio & Plan Configurations on Seismic Performance of Multistoreyed Regular R.C.C. Buildings: An Evaluation by Static Analysis" concludes that, (a) The buildings with Horizontal Aspect Ratios 4 or less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive forces, storey drift and displacement values may be obtained. Hence they should be discarded due to their unsatisfactory, weaker and unreasonable performances on the bases of above seismic parameters, which can cause detrimental and disastrous effects or otherwise be treated with the enough earthquake resistant elements. (b) The buildings with Vertical Aspect Ratios less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive overturning, storey drift and displacement, period of vibration, etc. values may cause detrimental and disastrous effects to the buildings. Hence slender building configuration, as far as possible, should not be chosen, or otherwise be provided with the adequate earthquake resistant solutions. (2). Flexible Tower on Rigid podium UBC-97 Section 1629.8.3 item 4 says "Structures having a flexible upper portion supported on a rigid lower portion where both portions of the structure considered separately can be classified as being regular, the average story stiffness of the lower portion is at least 10 times the average story stiffness of the upper portion and the period of the entire structure is not greater than 1.1 times the period of the upper portion considered as a separate structure fixed at the base." And UBC-97 Section 1630.4.2 Item 2 says 2. The following two-stage static analysis procedures may be used for structures conforming to Section 1629.8.3, Item 4. 2.1 The flexible upper portion shall be designed as a separate structure, supported laterally by the rigid lower portion, using the appropriate values of R and ρ. 2.2 The rigid lower portion shall be designed as a separate structure using the appropriate values of R and rho. The reactions from the upper portion shall be those determined from the analysis of the upper portion amplified by the ratio of the (R/ρ ) of the upper portion over (R/ρ ) of the lower portion.
  2. W.Salam, There is no option for the Triangular loading in ETABS. But in SAP2000 you can use the JOINT PATTERN option for the application of Triangular Loading...
  3. See the Attached self explanatory picture.
  4. @Ayesha Let me demonstrate that statement with a simple 2D frame in ETABS....
  5. Taimoor, I would recommend you to start learning Autodest Robot Structure Analysis Professional and Revit Instead of 3Ds Max.....
  6. The RC members in a physical structure crack well below the ultimate load.Therefore using full MOI of the member in idealized model is not justified. Though the use of full MOI will not affect the total value of bending (positive plus negative), the distribution b/w the members may change considerably. It is not the absolute MOI that matter,rather it is the relative stiffness of members that must be considered. In short, these modifiers (reductions in MOI) are used for the calculation of deflections i.e Serviceability checks...
  7. In order to find the TIME PERIOD,seismic weight and Base shear used by ETABS in analysis, go to DISPLAY--->Show tables and display "Auto Siesmic Loads" in the Load Definitions under Model definition.... See the attached screen shots...
  8. Dear Engineer, KPK Seismic Field Practicing Manual is attached. Field Practice Manual on basics of good construction practices.pdf Thanks.
  9. W.salaam Waqas, We have various Seismic-force resisting systems defined in different codes/standards with different nomenclature. You can study these Systems in detail in these tables; BCP SP-2007, Table 5.13-Structure Systems ASCE 41-13, Seismic Evaluation and Retrofit of Existing Buildings,Table 3-1,Common Building Types ASCE/SEI 7-10, Minimum Design Loads for buildings & other structures,Table 12.2-1 Design Coefficients and Factors for Seismic Force-Resisting Systems Modelling Structure either as BARE FRAME or FRAME with MASONRY INFILL in ETABS/SAP/STAAD PRO/ROBOT Structures/Seismostruct is the designer design approach that how he want to resist the gravity/lateral Loads. By Modelling wall in model it becomes a DUAL System (Concrete Frame with masonry shear walls) BUT the idealization of masonry walls is not as simple as other elements like Beams/columns/slabs/RC Shear walls etc. It requires more experties/understanding (Study Section 11.4-Masonry infills of ASCE 41-13,Seismic Evaluation and Retrofit of Existing Buildings for detail). Proper anchorage should be provided b/w masonry and RC frame. We mostly/commonly design our Concrete structures as BARE FRAME (Moment resisting frame without Infill walls) and assign wall load on the beams. By doing this we are neglecting the masonry walls stiffnesses which results more ductile frame (Ductility is more desirable in structures).Proper steel reinf. detailing is required and gap filled with thermopore or any other insulating material is provided b/w the RC frame and masonry wall (inorder to prevent the hammering action of masonry on RC Frame during EQ). Most of the 2,3 story houses are constructed as CONFINED MASONRY STRUCTURES and these structures perform very well in EQs.
  10. Really very nice gathering. it was my first meeting with all the members but due to our discussions on this forum for the last couple of years, I didn't even feel once for the 3-4 hours meeting that we were meeting for the first time. Thank you all....
  11. Thank you sir for such a detailed report....... i was about to ask you for this. here is a snap shot of my SAP model showing the water pressure on the Tank walls.
  12. I hope this snap shot will clear all the confusions.....
  13. AOA Dear @Rana What is the status of OStruc. I am contacting the OStruc team through info@ostruc.com but the mail is failing continuously.
  14. Stiffness Modifiers are generally applied for considering cracked section analysis in our design, so it directly affect deflections. Directly it is not affecting Moments BUT indirectly it is affecting the moments by moment redistribution.