Part 5 / Check P-Delta effect According to ASCE7-16

السلام عليكم ورحمة الله وبركاته
الفيديو دة بيشرح تاثير ال p-delta effect على المبانى فى برنامج الايتابس وكيفية عمله بمساعدة شيت اكسيل طبقا للكود الامريكى
#pdelta #analysis #Etabs
In this video discuss about,
1) How to apply P-Delta Check (Or Stability Coefficient)
2) Why P-delta is impotent
3) How to include P-Delta effect in analysis (Part 2 video)
P Detla check Excel Sheet
docs.google.com/spreadsheets/...
P-Delta effect, also known as geometric nonlinearity, involves the equilibrium and compatibility relationships of a structural system loaded about its deflected configuration.
1) P-δ effect, or P-"small-delta", is associated with local deformation relative to the element chord between end nodes.
2) P-Δ effect, or P-"big-delta", is associated with displacements relative to member ends.
Initial P-Delta analysis may be specified in ETABS
Define P-Delta Options and using either of the following two methods:
1) Non-iterative Based on Mass, in which load is automatically computed from the mass at each level.
The benefit of this non-iterative method is that P-Delta may be considered in load cases which do not specify gravity load. When gravity load is specified, we generally recommend the Iterative
2) Based on Load Cases method.
Iterative Based on Load Cases, in which load is computed from a specified combination of static load cases, then known as the P-Delta load combination.
When the iterative method is selected, two additional options become available :
Convergence Tolerance (Relative), Iteration is used to make sure that equilibrium is achieved at each step of the analysis.
A P-Delta load combination of 1.2 DL + 0.5 LL is typically conservative when considering P-Delta effect due to the overall sway of a structure. Combinations (3) and (4) will accurately capture this effect, while (5) and (6) should be conservative. Combinations (1) and (2) have no lateral load, therefore P-Delta effect should not be of concern. Please notice this is a non-linear static case and should be performed only after the model runs without any numerical issues for simple linear cases and results of basic variables such as deformations are within realistic or expected values.
How to include P-Delta effect in analysis
The two primary means for including P-Delta effect in nonlinear analysis include:
1) For each load combination, create a nonlinear analysis case which includes the P-Delta geometric-nonlinearity parameter.
2) For the gravity loads anticipated, create an Initial P-Delta Analysis case which includes the P-Delta geometric-nonlinearity parameter, then consider all other analyses as linear while using the stiffness matrix developed for this one set of P-Delta loads.
Reference CSI Technical Knowledge Base
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[@ahmedelmaghraby9066]

السلام عليكم
شكرا لمجهودك يا بشمهندسة
سؤال هل لو انا اخدت ال p delta فى الاعتبار كل مرة حتى لو قيمتها اقل من 0.1 هتسبب مشكلة؟

[@bothainaosama92]

مفيش مشكلة لو اخدتها معاك دايما ..الفكرة انك هتزود المومنت على قطاعات الشير وال والاعمدة وبالتالى التسليح هيزيد ..ولو عندك اعمدة long columns خدها فى الموديل دايما عشان التصميم يكون ادق

[@hahmed9797]

السلام عليكم ,اولا اوجه الشكر للمجهود يابشمهندسة ربنا يزيدك من علمه .كان عندي مشكلة في اظهار النتايج ETABS 21 من ال Table وانا بظهر قيم ال story forces وكده لما بروح اعمل filter بيظهر حالات ال load cases بس انما ال combo لا رغم انه مخليه يدخلها معايا .وبالتالي مش عارف قيم ال Px

[@hahmed9797]

مع العلم علي برنامج ETABS16 بتظهر عادي

[@bothainaosama92]

وعليكم السلام تسلم يا بشمهندس...وانت بتختار ال load cases اختارها كلها وبرده اختار كل اللى load pattern وبعد كده select combos واعمل o. K... هتلاقى ال table ظهر فيه كل الحالات.. فهمتنى؟

[@hahmed9797]

اختارتهم وبردو مفيش ولا حاله من الcombo بتظهر

[@bothainaosama92]

طيب جرب تطلع نتائج تانيه زى reaction الاعمده.. وشوف كده حالات ال com هتظهر ولا

[@hahmed9797]

حاولت بكل الطرق اصلا الخانه بتاعتoutput كلها مبتاخدش نتايح الcombo.. نزلت اصدار ٢٠ بردو مبتظهرش. مظهرش غير في اصدار ١٩

[@muhammadkareem1284]

السلام عليكم
الدقيقة 13:03 لماذا تم تغيير set modifier
هل دائما وهل في كل check؟

[@bothainaosama92]

لان ال check for p delta لازم يتعمل فى حاله ال service طبقا للكود عشان كده تم تغيير المعاملات... بنعمل كده بردع فى check story drift.. باقى ال checks عادى بنخلى ال modifier in ultimate

[@muhammadkareem1284]

@@bothainaosama92
الله ينور عليكي ومشكوره يابشمهندس