EngrUzair

IMO, you must check & verify your design through manual calculations. Following links provide procedure and examples, for designing of strap footings manually: 1. Strap Footing- Shallow Foundations.pdf 2. Special Footings and Beams on Elastic Foundations.pdf 3. Strap Footing Design.pdf Regards.

If you design , detail & place strap beam as a part of strap footing in accordance with ACI code provisions (elaborated in design example referred in my previous post), it should work as strap beam. Otherwise, IMO it might act as tie or plinth beam, rather than a strap beam.

Where is this reduction mentioned or recommended? In some code, book or manual?

Sohaib, For basic theory & assumptions regarding dome design, you may consult following links, in addition to the books dealing with design of shell structures: 1. Reinforced Concrete Dome Design- RCC Dome Design.pdf 2. Design Principles and Analysis of Thin Concrete Shells, Domes and Folders 3. Design and Construction Criteria for Domes in Low-Cost Housing 4. Design of Circular Domes by PCA- design_of_circular_dome.pdf Modelling of a dome in SAP2000 is illustrated in the following link: http://www.play-it.pk/watch?v=fM8r9hc9QbQ Regards.

Sohaib! Details regarding purpose of providing strap beam, as part of strap footings, are available in various RC design books, e.g., Design of Concrete Structures by Nilson, etc. Some related information & reference to a solved design example are available in following thread: http://www.sepakistan.com/topic/1967-should-strap-beam-be-monolithic-with-the-isolated-footing/ Regards.

I have not studied RSA in sufficient detail. As such I might not help more in this regard. However, other people here who are experienced in use of RSA might see this & help as well. Regards.

Yes. When following procedures of UBC Section 1631.2, R value is not to be used

Basically, you will need to go through STAAD.Pro Technical help & manuals to understand the procedure. Following links might also be helpful in this regard: 1. http://playit.pk/watch?v=58nHw9d7syM 2. http://www.sefindia.org/forum/files/pdelta_and_buckling1_156.pdf 3. http://playit.pk/watch?v=nu37r2IVG58 4. http://playit.pk/watch?v=SZ1trg0fZDA 5. http://playit.pk/watch?v=0ZbDfRn4kHo HTH

Dear Umar! I have already noticed some of the improvements mentioned above, e.g., different notifications. Other features will certainly be clear over time, when I will start using them. However, I feel that some basic features are missing in this upgrade (may be I was unable to locate them), as compared to previous forum interface. First of all, I could not figure out how I can preview my post, before actually uploading it. Secondly, 'Undo' and 'Redo' features are absent from the editor toolbar. Thirdly, the 'user controlled' Save option (I was looking for) is still unavailable. Fourthly, I am unable to see Members Listing & Their profiles. Previously, this information was readily available, as a distinct menu item. Regards.

Following are the links of some software that might help you in this regard: 1. http://www.steelchecks.com/connections/home.asp#.VvMD0DHG9ko 2. http://www.bimware.com/en/software/master-for-the-eurocodes/master-ec3-steel-connections 3. http://www.consteelsoftware.com/en/products/csjoint 4. http://www.buildsoft.eu/en/product/powerconnect You may also find more links through a simple web search. HTH

Although bottom levels of the strap and the two connected footings are generally not the same, and strap bottom level is a bit higher than the bottom face of the footings, the strap beam has to be cast monolithic with the footings. For further clarification, please see Example 16.4 (especially the last paragraph) related to the design of a strap footing according to ACI 318, at the following link http://www.chegg.com/homework-help/complete-design-strap-footing-example-164-determine-dimensio-chapter-16-problem-6p-solution-9780073293493-exc?adobe_reloaded=true:

I am unable to open your model in version 9. Which ETABS version you are using? If you could attach text input file (.$et) of you model, I may try to open it in ETABS9 to see what the problem might be.

Dear hussainm, In general, larger the frame span or bay spacing, heavier will be the structural members. Morever, higher the yield strength of steel (e.g., 50 ksi), lighter will be the members, when compared to members made of lower yield strength (e.g., 36 ksi for a36) steel. Since you are not designer, it would be better to advertise your requirements (required shed size & height, No. & capacity of cranes, and most economical design etc.) in a few high-circulation newspapers, asking for design proposals from the specialist firms having experience of design & construction of such sheds. In this way, you may get more than one design proposals to select the one that not only best suits your needs, but is economical as well. Regards.

Thanks for the update. I have scanned the links you have referred to. However, I am unclear about whether the features I requested in my following post (http://www.sepakistan.com/topic/1865-major-update/#entry5168 ) are being added or not? Would you like to throw light on that? Regards.

Dear Umar! Has the forum been updated, or is yet to be updated? What are the major improvements either made, or still to be implemented? Regards.

Check the attachment: P-delta_analysis_parameters.pdf HTH

Assalam-o-alaikum! Dear Colleagues, Please see the attached image, showing Uniform Reinforcing Pier Design details of a RC shear wall, designed using ETABS 9.7.4. In addition to providing structural details, the output displays some error messages as well. In this connection, I want to know: 1. What type of design or structural problems do these messages indicate, especially the Design Inadequacy Message? 2. How these error messages can be avoided? Note: It is a 2B+10-storey building, located in seismic zone 2B, and modeled as an IMRF. Material design code is ACI 318-99 and seismic design is based on UBC 97. Regards

See the following links & attached images: 1. http://en.allexperts.com/q/Civil-Engineering-1357/2010/1/Center-mass-Etabs.htm 2. https://www.s-frame.com/index_files/Files/CaseStudyNo1.pdf Regards.

Please see the following links for a good explanation of the difference: 1. http://www.sepakistan.com/topic/165-slab-elements-in-etabs/ 2. http://www.slideshare.net/neikrof/membrane-plate-shell 3. https://wiki.csiamerica.com/display/etabs/Membrane+vs.+shell+slab Regards.

W/Assalam. According to BCP Table 5.13, R value for an Undefined Structural System should be selected as per procedure given in BCP Section 5.29.9.2. However, IMO the problem may be tackled in the following manner, as well. In case structural details about the existing RC structure are not available, it may be considered as an Ordinary Moment Resisting Frame (OMRF) at the most, with a tabulated R value of 3.5. On the other hand, third storey, proposed to be constructed in steel (cold-formed or hot rolled) may be assumed & designed as Steel OMRF (R = 4.5), Steel EBF (R = 5.6) or Steel SMRF (R = 8.5). However, in absence of reliable structural information about the existing structure, it would not be advisable to design the third storey for a higher R value, than the RC structure supporting it (the third storey). In such a case you may assign an R value of 3.5 to whole structure, to be on the safer side. However, in case you do have exact or reliable structural data for the existing structure, and you are satisfied that it can be classified as an IMRF or SMRF, you may use a higher R value for the whole structure, including the additional storey. I hope that before proposing the third storey, you would have already checked that the footings are capable of taking the load of the additional storey safely. HTH Regards.

AFAIK, ETABS 9.7.4 has Autoselect option for steel members only. Therefore, I am also interested in knowing how to make and apply Autoselect list in ETABS, in case of RC members. Regards

If you could upload a few sketches or cross-sections of the bunker and the office, in order to clarify levels & location of the two structures with respect to each other, it might facilitate the forum to provide you with a better advice.

AFAIK, ETABS (& probably SAP2000 as well) indicates required reinforcement ratio, in cases where it is less than maximum steel ratio. Otherwise, member is marked as 'O/S #2 ', indicating that the required reinforcing is more than maximum steel ratio. However, required reinforcement ratio is not output by the software in the later case. This is in line with general practice (especially in case of columns) that actual amount of reinforcing steel is kept below 50 percent of the maximum permissible steel ratio, in order to facilitate splicing of reinforcement at different floor levels (where actual steel ratio will be doubled due to lapping of bars). On the other hand, in case of beams, required area of steel given by ETABS might be more than maximum steel ratio. Whether the required reinforcing is less or more than the maximum permissible steel ratio, has to be checked & verified by the designer himself, manually or through a purpose-made spreadsheet. Regards.

In general, ACI 318 is a Material Design Code, governing the structural design of Reinforced & Prestressed Concrete elements & structures only. On the other hand, UBC 97 is a complete Building Code. It provides specifications for most parts of a building structure, whether structural or non-structural. It includes design requirements, not only for concrete elements (as does ACI 318), but also for several other types of structural materials e.g., Structural steel, masonry and wood etc. Moreover, it provides specifications and requirements for non-structural building components as well. A common use of UBC 97, in our country, is as a 'Loading Code' for calculation of mainly earthquake loading for framed structures (either concrete or steel). HTH Regards.