14-ASCE-7 Seismic Provisions-CONFIGURATION IRREGULARITIES- Dr. Noureldin

CONFIGURATION IRREGULARITIES
Plan (Horizontal)Structural Irregularities
1a - Torsional Irregularity
1b - Extreme Torsional Irregularity
2 - Re-entrant Corners
3 - Diaphragm Discontinuity
4 - Out-of-plane Offsets
5 - Nonparallel Systems
Vertical Irregularities
1a - Stiffness Irregularity -Soft Story
1b - Stiffness Irregularity - Extreme Soft Story
2 - Weight (Mass) Irregularity
3 - Vertical Geometry Irregularity
4 - In-plane Discontinuity in Vertical Lateral Force Resisting Elements
5 - Discontinuity in Capacity - Weak Story

[@abdulkareemibhais6396]

Thank you Dr. Mohamed for this valuable lecture...
I wonder if you can share those slides for better comprehension?

[@yousefsalaymeh8586]

Thanks for your effort Dr.Nour,
but I have a question about "Out-of-plane Offsets", should I use overstrength factor to design foundation or using only for the element connecting directly with shear wall.

[@noornoori6722]

Dear Sir, how we can increase 25% forcec for connection, shall we go for load combinations, if yes which load combination should be considered to increase forces 25%?

[@marcospaniagua2697]

Hi I wanted to ask,
Does it make any sense for me to check torsional irregularity on the X using a lateral load in the for (100x + 30y). Or would it make more sense judt using 100x for X and 100 y for Y?

[@ARROW2013]

Dr Mohamed
I have a question regarding type 5 irregularity. Can you explain how you calculate the story shear of the braced frame example. The story shear of the second story is brace tension and compressive capabilities. The first story, there are only columns so is it the shear capacity of the cross section?
Thank you

[@ghazijumaa1648]

Thank for these lectures, kindly, what is the difference between Remedial measures 3 and 5 (3D dynamic analysis and modal rigorous analysis)

[@mrnour20]

The modal rigorous analysis may not require the consideration for diaphragm stiffness, using cracked section properties for concrete elements, or Inclusion of PΔ effects. Both remedial measures (3 and 5) may overlap in using 3D dynamic analysis, but they are different in the details included.

[@ghazijumaa1648]

@@mrnour20 Thank you God bless you.

[@ghazijumaa1648]

for horizontal irregularity type 5: required remedial measures (3, 5 and 8) 8 allows use of ELF while 3 and 5 do not allow it , can we use ELF or not? there is confusion?

[@mrnour20]

Thank you for your comment.
Remedial measure 8 is related to the direction of loading in general. It says “Use 100x + 30y, if you are using ELF or modal analysis. Use the simultaneous application of load, if you are analyzing the structure using a linear or nonlinear response history procedure (ASCE 7-05, Section 12.5.3).”
In the case of SDC “C”, structures that have horizontal structural irregularity Type 5 in Table 12.3-1 shall use one of the following procedures:
1. Orthogonal Combination Procedure using ELF, modal response spectrum, or linear time history, or
2. Simultaneous Application of Orthogonal Ground Motion using the response history procedures.
Based on that, ELF can be used for SDC “C”. Other SDCs can use more rigorous procedures
.
I think there is no confusion now.

[@ghazijumaa1648]

@@mrnour20 Thank you God bless you.

[@ghazijumaa1648]

Why only in remedial measures 8 ask for using 100x+30y ? is that mean we do not use it in other cases?

[@mrnour20]

Remedial measures 8 is required for SDCs C through F, but not required for SDC B (section 12.5.2 in ASCE7-05).

[@ghazijumaa1648]

@@mrnour20 Thank you God bless you. hope all the best for you