Design Analysis of Tower Bolts by Kotur Raghavan

In this article we will look into design requirements of tower bolts which we find as integral part of the doors of residential buildings. Design of exterior doors will be assessed from security point of view. Typical tower bolt arrangements are shown in the figure below.

Fig. 1

The main part of the bolt is fastened to the door through set screws. When the door is to be secured the bolt will engage into the socket which is fastened to the frame through set screws. When all the bolts are in engaged position the door and the frame will be nearly integral. The security concern is that a burglar may use force from outside and break open the door.

Load Transfer

When any pushing force is applied to the door from outside, the load gets transferred to the frame partly at hinge locations and partly at socket locations. The latter force will have tendency to pull the sockets from the frame. In the entire assembly the set screw connections between the sockets and the frame happen to be the weakest points. For a given value of the applied force, the force coming on to the sockets can be considered to be ‘figure of merit’. Lesser the better. Rest of this article will focus on development of analysis model for computation of forces coming on to the sockets.

Structural Aspects and Simulation Model

There are two main structural parts. The assembly of bolts and the door is one. The other is the assembly of frame and the sockets. When the load is applied from outside, it is transferred from the door assembly to the frame assembly at hinges and bolt locations. At the hinge locations, the load transfer is through rigid connections. At the bolt locations, the load transfer is through contacts. At this point, we take a look at the purpose of analysis. The main results of importance are the forces transferred from the socket to the frame. As the sockets and the frame are in series, these forces will be equal to the reactions at set screw locations if the sockets are constrained. It is even more so as the frame, being firmly built into the wall, is relatively, very stiff and can be considered to be rigid. Likewise, the door can be considered to be constrained at hinge location. Elimination of the frame from the analysis model is the first approximation.

We use the same logic to simplify simulation of socket. The bolt pulls the socket through contact and the same pulling force is experienced by the screws. Thus we arrive at the second approximation resulting in elimination of the sockets and associated contacts from the model.  Consequently, the tower bolts happen to be structural elements bonded to the door and constrained at the (socket) screw locations.

As the door thickness (about 30 mm) is very small relative to the door dimensions (1200 * 2000 mm), it is adequate to use shell elements in the simulation model.

F. E. Model and Results

The finite element model is shown in the figure below.


                                                                               Fig. 2

An arbitrary load of 500 newtons is applied. This is representative of the force generated when a strong man kicks the door from outside. The load is assumed to be uniformly distributed over a region of 100*100. For the purpose of comparison four different analyses are carried out corresponding to four different load application locations. The locations are in indicated as L1, L2 etc. in the figure below. In the figure are also shown reaction points R1 to R6 for reference.


                                                                                    Fig. 3

Typical results are shown in the figure below. These are for load application at L1. It contains deformation contours and reaction values. R2 and R4 are positive reactions whereas R1 and R3 are negative reactions. This indicates that there is local bending effect. Total reaction force from six constraints is about 340 newtons. Difference between this and the applied load will be equal to total reaction force at hinge locations.

Fig. 4

The computed reaction forces for other loading conditions are given in the figure below. Qualitatively they appear to be correct.

Fig. 5

The foregoing is for qualitative understanding only. As we do not know the the strength of set screws and also because the load applied is arbitrary, no design inferences are intended.

The foregoing results are obtained for bolt length of 100 mm. Tower bolts are available in different sizes. Typical options are shown in the figure below.

Fig. 6

We note that for all the bolt sizes, the socket dimensions are unchanged. In all the cases the socket has provision for two set screws only. Intuitively it can be felt the longer bolts may not be advantageous from a security point of view.

Fig. 7

Reaction forces for bolt length of 200 mm are presented in the figure above. These are for the centrally applied loading condition (L2). The values corresponding to 100 mm length are in the inner box. We see practically no difference between the two sets of results.

Summary

1.       This study was taken up just as an exercise in simulation. Simulation means mathematical representation of a physical process. The model developed will be useful for assessing the adequacy of tower bolts. Based on the approach one can carry out parametric studies to arrive at optimum configurations.

 

2.       An important lesson has been on how to develop simulation models keeping in mind the purpose of analysis and the results of design importance.

 

3.       One needs to find justification for paying more money for longer tower bolts. Purely from a point of view of security the additional money spent may not be worth. 

Comments

  1. Nice reading, I love your content. This is really a fantastic and informative post. Keep it up and if you are looking for Door installer in Mornington Peninsula then visit JC Window and Door Replacements.

    ReplyDelete
  2. I found your blog on Google and read a few of your other posts. I just added you to my Google News Reader. You can also visit Grade 12.9 Bolts for more Jignesh Steel related information and knowledge, Keep up the great work Look forward to reading more from you in the future.

    ReplyDelete

  3. Thanks for sharing the best information and suggestions, I love your content, and they are very nice and very useful to us. If you are looking for the best ss hex bolt manufacturers, then visit Vinesh Steel. I appreciate the work you have put into this.

    ReplyDelete

  4. Thanks for sharing the best information and suggestions, I love your content, and they are very nice and very useful to us. If you are looking for the best Stainless Steel Welded Pipe, then visit Ashtapad Overseas I appreciate the work you have put into this.

    ReplyDelete
  5. Thanks for sharing the best information and suggestions, I love your content, and they are very nice and very useful to us. If you are looking for the best Api 5L ERW Pipe, then visit Victor Steel. I appreciate the work you have put into this.

    ReplyDelete
  6. Thanks for sharing the best information and suggestions, I love your content, and they are very nice and very useful to us. If you are looking for the best ss 304 flanges manufacturer in india, then visit Great steel & metals. I appreciate the work you have put into this

    ReplyDelete
  7. It was such a good post. Visit ss 304 bolts. Thanks for sharing.

    ReplyDelete
  8. I read the above article and got some knowledge from your article which is about door and window repair for us .It's actually great and useful data for us. Thanks for sharing it.

    ReplyDelete
  9. Really helpful down to the ground, happy to read such a useful post. I got a lot of information through it and I will surely keep it in my mind. Keep sharing. If you are looking for some useful data and information regarding Stainless Steel Threaded Rod manufacturers then visit Raaj Sagar Steels.

    ReplyDelete




  10. I agree with a lot of the points you made in this article. If you are looking for the 316 stainless steel fasteners, then visit Regal Sales Corporation. I appreciate the work you have put into this and hope you continue writing on this subject.

    ReplyDelete
  11. Hi to every single one, it’s truly a good for me to visit this web page, I love your content, they are very nice and it includes helpful Information. Check out our website hex bolt manufacturers in india for more Viha Steel & Forging related info! I am truly pleased to read this website posts which carries lots of helpful data, thanks for providing these kinds of statistics.

    ReplyDelete
  12. After going through your contents I realize that this is the best of my knowledge as it provides the best information and suggestions. This is very helpful and share worthy. If you are looking for the best b16.5 flange then visit Rajendra Piping & Fittings. Keep sharing more.

    ReplyDelete

  13. Thanks for such a pleasant post. This post loaded with lots of useful information. Keep it up. If you are looking for the best information and suggestions related to 254 SMO Sheet suppliers then visit Perfect Impex.

    ReplyDelete

  14. Thanks for suggesting good list. I appreciate your work this is really helpful for everyone. Get more information at 3 way ball valve. Keep posting such useful information.

    ReplyDelete
  15. Wow, excellent post. I'd like to draft like this too - taking time and extremely hard work to make a great article. Visit high tensile fasteners. This post has inspired me to write some posts that I am going to write soon.

    ReplyDelete
  16. You have Shared great content here about Patio Doors Columbus Ohio I am glad to discover this post as I found lots of valuable data in your article. Thanks for sharing an article like this.

    ReplyDelete
  17. Thanks for discussing, great news. This type of news is really appreciative. I have great news. Your article is very informative, Visit alloy steel pipe suppliers in india. Thanks for sharing.

    ReplyDelete
  18. Article ideas very clear. Your writing style is very unique. I very much appreciate the articles you write. Please visit to know more information about ASTM A240 UNS S32750 Sheet. You can also visit my blog at Duplex S31803 plates.

    ReplyDelete
  19. It is really very helpful for us and I have gathered some important information from this blog. For relevant things visit Stainless Steel 304 Fasteners. Visit my blog at Duplex S31803 plates.

    ReplyDelete
  20. Your blog is awfully appealing. I am contented with your post. I regularly read your blog and its very helpful. If you are looking for the best 410 Stainless Steel Strips, then visit Sonic Steels. For more relevant things you can visit my blog at Stainless Steel Hex Bolts.

    ReplyDelete
  21. Happy to read such a useful post. I got a lot of information through it and I will surely keep it in my mind. Keep sharing. If you are looking for some useful data and information regarding 304L Stainless Steel Slitting Coil then visit Jainex Steel Impex. Please also take a look at Stainless Steel Hex Bolts.

    ReplyDelete
  22. In this post, all information and suggestions are helpful for us. Keep sharing more Post like this. For more information relevant things please visit Stainless Steel 304 Seamless Pipes.

    ReplyDelete
  23. Informative blog, Which help us to understand information easily and fast. Keep sharing more info on this IPE BEAM Visit Ranflex Metal to more relevant services.

    ReplyDelete
  24. I am really impressed with your blog article, such great & useful knowledge you mentioned here. Your post is very informative. For more information you can visit STAINLESS STEEL 304 BOLTS.

    ReplyDelete
  25. Good and very informative post I must say. I have used many types of Heavy Hex Bolt Fastener for my projects. Thanks for sharing this wonderful post.

    ReplyDelete
  26. It is an informative piece of guidance provided by you. Very glad to find this information here and I am sure that it is beneficial for Everyone. Please also take a look at Solid Copper Earth Rod.

    ReplyDelete
  27. Share great information about your blog , Blog really helpful for us . handyman services ottawa

    ReplyDelete
  28. Share great information about your blog , Blog really helpful for us . handyman service orleans

    ReplyDelete
  29. Share great information about your blog , Blog really helpful for us . tile installation in ottawa

    ReplyDelete

Post a Comment

Popular posts from this blog

Saint-Venant’s Principle, Interpretations and Applications by Kotur Raghavan

Minimum Constraints in FEA – 4. Inertia Relief Application by Kotur Raghavan

Minimum Constraints in FEA – 5. Submodeling by Kotur Raghavan