please refer to blog article links provide related to original graphics posted instead of sending any personal opinions. The bolt also can resist compression for special case of anchorage in concrete; distribution also may vary depending on end plate thickness, member connected and configurations. Unfortunately, no words in prestressed at these articles, so be consistent.
regarding zero shear forces, is rare and it can be verified by extracting from global portal frame analysis and generate sub-models. The big pictures are in joint equilibrium i frequently struggle. I’m only explaining shear resistance system effectiveness between bearing type and prestressed bolt by clamping for case of beam to column connection.
I wish it were that easy. There are important differences.
-Preload on bolts is an internal force not external.
-That formula assumes a fixed pivot point at the center of the plate.
-Formla assumes all the elements are rigid.
-Piles can manage tension and compression. (±)
……..
Each section descrived in the idea Statica webpage gets closer to the real behaviour of the connection. Each one has different assumptions behind that requires a different set up in ccx.
-Point one is wrong so I don’t think it is of interest.
-Point two assumes Rigid body plate and Column. Pivot point moves to the base. You need nonlinear contacts to model that. Bolts do not sustain compression so Nonlinear contact on the Bolt heads too.
-Point three same as Point two but Rigid Body is relaxed.
-Point four involves a more accurate moeling of the real geometry.
-Point 5 it’s just an optimizazion according to the previous result removing some bolts.
You could even go further by adding plasticity and preload.
Idea statica has the advantage of shells much more easy to set up the model but …is not free .
I’ve found a very recent article (December 2025) comparing the results for joints under tension/bending with and without preload. Unfortunately, the legend and axis labels are barely visible and written in Polish so I had to fix them. This is the joint:
The results clearly indicate the beneficial effect of bolt compression on the performance of the connection. Up to a moment of ~ 100 kNm, the forces in the prestressed bolts remain almost constant, which indicates effective load transfer through the pressure between the plates. Only after exceeding this value is an increase in the forces in the bolts observed, resulting from the increased significance of the lever effect. It is worth noting that in both prestressed and non-prestressed connections, faster force increases are observed in the second row of bolts. This is due to the fact that the plate in this location has stiffer support in the form of beam walls (flange and web). No significant changes were observed in the lower rows of bolts, which is a consequence of the slight tension in this area of approximately 30 kN for row 3 and 10 kN for row 4 at a load of 200 kN.
Analysis of the influence of the lever effect on the upper bolt rows confirmed that this phenomenon becomes dominant at higher torque values. The additional forces in the bolts result mainly from local deformations of the end plate.
I’ve checked several books and other papers too, but they mostly focus on the influence of preload on the stiffness of such joints. I will get one interesting book arrive after the weekend, though.
I would probably do it in another software, more efficient for these kinds of models (e.g. having bolt connectors) first, but you already did it, so I’ll probably stick to literature research for now and leave the fun part to someone who has more time for that and to the OP (btw. it would be good to finally see and discuss his setup).
At some point I may do it for a tutorial, but the list of the topis to cover in the near future is already very long.
point one in these blog article cannot be wrong; are someone think this such a bolt does not resist compression i.e some holds to stay on the fly all the time?
@synt , bolts are allowed to take compression only if they are asked to.
Here in the picture base plate is not rested on concrete.
Bolts are provided both at the top of plate and at the bottom of plate so that they can take both compression and tension.
But the primary reason to provide the bottom bolts is to adjust the level of the poles.
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