Muhammad Imran Zafar

Dear Waqar you may use ABAQUS for crack analysis. By simulating temperature gradient you may also use ETABS for crack width calculations

Dear Waqar please follow ACI 224 "Control of Cracking in Concrete Structures". It can easily be downloaded and lucidly furnish guidelines. You may also consult Handbook of concrete engineering by Mark Fintel

Dear Waqar please check the pouring methodology and measures adopted to control temperature for mass concreting, if any. Then you can calculate the temperature rise during hardening of concrete and compare the difference of atmospheric temperature and concrete temperature. As very high cement content is anticipated so stringent temperature control requirements should have been adopted. By this you would be able to figure out whether these are temperature shrinkage cracks or otherwise. Moreover please calculate the crack width. As cover is high therefore there is a possibility that you may end up in calculating the crack width equivalent to whatever is visible there in the slab. Pattern of cracks you highlighted indicates the temperature shrinkage nature of cracks however calculations are needed to confirm the anticipation.

Having seen the contribution of shear walls and columns in resisting base shear, Dual system would be more appropriate. you just need to increase contribution of column to minimum 25 percent in y direction. This can be either done by reducing length of shear wall in y direction, increasing stiffness of columns in y direction or doing nothing of either and just check the design of frame for independently resisting 25 percent of the design base shear in y direction. In x direction your structure has already qualified the requirements of dual system.

pour strips can be effectively used to mitigate column and wall creep and shrinkage, restraint of creep and shrinkage in long floors or roof systems, creep caused by prestress forces and volume changes caused by variation in temperature. It works in irregular plans as well. Moreover at the moment you have one irregular shaped foot print, by providing expansion joints as marked in red on above posted plan, you'll be facing at least two irregular foot prints.

Yo can use closure strip or pour strip instead of expansion joint (This will certainly not make building configuration better). Do consider the temperature effects in Analysis and design the building as an irregular structure.

Walikum us Salam 1- Concrete having strength 30 mpa is not a lean concrete. In fact Aci 318-19 chapter 19 prescribes minimum strength of 2500 psi for structural concrete which is slightly more than 17 mpa. 2- For plain concrete footing refer to ACI 318-19 chapter 14 in general and 14.3.2 in particular. 3- you need to design the thickness on basis of reaction and footing offset.

For structural walls ACI 318-19 11.7.2.3 states that " For walls with thickness greater than 10 in., except single story basement walls and cantilever retaining walls, distributed reinforcement in each direction shall be placed in at least two layers, one near each face." However for non load bearing concrete walls you may design your concrete wall as plain concrete walls as per chapter 14 of ACI 318-19. However if subject wall is not being covered with any sort of sheeting then temperature and shrinkage reinforcement must be provided (equally distributed among both faces), otherwise hair line cracks may appear and can create unrest among users.

One needs to make structural response controlled in the way as IS relevant clause has indicated. As far as torsional amplification is concerned that is dealt separately by amplifying torsional eccentricity. Modal response is dealt separately by controlling modal response. Like there are situations in which you can have planner torsional irregularity yet torsional mode is coming after translational modes. But if it is not so then you need to balance the lateral stiffness in such a way that torsional mode does not become the first or second mode. This can be done in several ways. you can add additional shear walls in one of the either axis after studying response. One can alter the thickness of already placed shear walls differently in both principle axes. At times in dual systems one can improve the modal response by changing column dimensions. As structural engineers we need to strive for improving response of structure by using any combination of alterations in lateral force resisting system.

You need to manually assign "k" factor, your columns are fine except columns at open edge. You need to assign demand capacity ratio of 1 instead of 0.95, your rafters are fine except the rafters at open edge. you need to strengthen you edge column, edge rafters and purlins. For purlins addition of cross members (sag arresters) may help in controlling slenderness and stresses. Thanks

What sort of help is being solicited please elaborate. As far as attached document is concerned, it indicates to neglect wind load which is not realistic for a 23 ft high steel shed in swat. In fact the the most critical load has been asked to be neglected. Rest of the data along with slope, type and loading of truss has been given. You should ask for bearing capacity as well.

Aci 318-08 section 13.2.5 and 13.2.6 address this issue and may be useful.

In ETABS frame section properties are assigned to line objects. However, actual structural members have finite cross-sectional dimensions. When two members such as a beam and column are connected at a point, there is some overlap of the cross-sections. In many structures, the dimensions of the members are large, and the length of the overlap can be a significant fraction of the total length of the frame element. ETABS provides the capability of defining end length offsets along the length of frame elements to account for these finite dimensions of structural elements. If the Automatic from Connectivity check box is checked, ETABS will automatically calculate the offset length. ETABS bases the end offset length at the end of the beam on the maximum section dimensions of all columns that connect to that end of the beam. This is the default. ETABS automatically calculates offset lengths for beam and column-type frame elements. It assumes the offset length for all brace-type frame elements to be zero. (You can define your own non-zero offset lengths for brace elements if necessary.) Also, the dimensions of brace elements that frame into the ends of column and beam elements are not considered when calculating the end offset dimension for a column or a beam. Beams. When ETABS automatically calculates the end offsets along the length of a beam, it bases the end offset length at an end of the beam on the maximum section dimensions of all columns that connect to that end of the beam. Columns. When ETABS automatically calculates the end offsets along the length of a column, it bases the end offset length at an end of the column on the maximum section dimensions of all beams that connect to that end of the column. If the Define Lengths check box is checked, enter values for the length of the offset at the start (End I) and end (End J) of the line object. (From ETABS) SO, In my opinion it is better to define the end length offset manually depending on size of connected beams keeping rigid zone factor as o. Thanks

Spectral acceleration describes the maximum acceleration in an earthquake on an object The spectral acceleration at different frequencies may be plotted to form a response spectrum. Peak ground acceleration (PGA) is a measure of earthquake acceleration on the ground

Please consult AISI. You may use STAD PRO and SAP for the purpose

Agreed, I prefer to use AISC. But at times on client's requirements it becomes a compulsion to use other codes.

All three approaches exist there. First approach deducts over burden ( which is the most common approach) Second approach is to go straight a way with B.C at that depth, this has many observations and is not practiced widely because 1) Soil has to bear load of super structure along with load of foundation 2) Allowable B.C is calculated on certain assumptions as well which are catred for by placing a factor of safety of 2 to 3. But keeping in view the factor of safety, we calculate size of footing on service load. So factor of safety has already been relied up on in terms of sizing the footings. Third approach is to add up the weight of excavated soil in B.c values. This is generally done for deep excavations like two or three basements. But with that approach geotechnical engineer recommends that excavated surface should not be left open for longer period. If one has excavated the site and there comes a halt in construction after excavation then site must be rechecked by geotechnical engineer before placing of foundation. This is so because soil starts to get relaxed and if cracks get developed then provision of adding up weight of excavated soil does not remain valid.

Pile foundation is the most suitable type, to me. For further assistance If you have geotechnical report do share it.

A structural system where against lateral forces, you are controlling response of structure by a combination of structural walls and columns, is dual system.

Dual system would be more appropriate, to me.

Please go through the following document. It may help in analyzing the two different approaches and then you can check your model accordingly. http://www.iitk.ac.in/nicee/wcee/article/14_05-01-0524.PDF

Well basically code considers a member as compression member when primary stress is longitudinal compression. The differentiation between column and wall is based on the principal use However code permits walls to be designed using principles stated for column. With that just to differentiate arbitrarily code defines columns basing on aspect ratio. In combination these two aspects support the point of view that member under your consideration should be treated as column and may be modeled as frame. Moreover moment diagram may not be a decisive factor in your case because what i got from discussion your member is a compression member. So the question is how to model that compression member.