HYLLA Tool

Rotationally Symmetric Pile Layout beneath Silo Foundations as a Preliminary Geometric Arrangement Proposal

Version 2026-09-30-4 · Calculation core 2026-09-30-4

This tool optimises an initial pile layout beneath circular or annular raft slabs. Linear superimposed annular loads, variable slab profiles, self-weight and an optional linear-elastic FE analysis in uncracked state I can be included. Results are available as lists, a 2D drawing, an interactive 3D model and export files.

The results support preliminary design but do not replace verifiable structural design, reinforcement or punching-shear design, or a project-specific engineering assessment. Settings are stored locally in the browser and can be deleted there.

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Geometry

Outer diameter D outside [m] Inner circle D inside [m] Load-free slab overhang [m] Pile diameter D [m] Pile length L [m] Radius of outermost pile ring [m] Specify radius of outermost pile ring Create outer influence ring first with pile centered

Fixed pile positions

Evaluate specified piles – without optimisation

Excel (.xlsx) matching the pile-list export or CSV with pile name, X and Y. X/Y in metres relative to the slab centre. CSV semicolons with decimal commas or commas with decimal points are detected automatically. Only names and coordinates are imported; loads and slab parameters come from this form. 3 to 500 piles. FE analysis is enabled automatically.

Load pile positions (Excel or CSV)

Area loads

Any number of annular zones, measured in metres from the inner slab edge. Equal end values define a constant load; different values define a linear variation. Overlapping zones are superimposed.

Default value for a new load zone q [kN/m²]

Slab thickness and elevation profile

The profile must cover the slab continuously from the inner to the outer edge. Define either thickness or separate top and bottom elevations with linear variation.

Default slab thickness [m]Concrete unit weight [kN/m³]

Define top and bottom elevations separately (funnel profile) Include slab self-weight

Optional FE analysis

Linear-elastic Mindlin slab in uncracked state I with discrete vertical pile springs. The optimisation compares FE candidates at the smallest feasible pile count. An inclined mid-surface is represented by local thickness, not shell action.

Include FE analysis in the optimisation

Pile spring stiffness [MN/m] Concrete class Radial FE divisions Circumferential FE divisions (multiple of 4) Maximum FE candidates

Iteratively optimise ring radii using FE pile reactions Target: maximum load deviation from mean [%] Maximum optimisation iterations

Deviation = 100 × max. |pile load − mean| / |mean|. Ring radii are moved and recalculated using FE; pile count, angles, fixed outer rings and the central pile remain unchanged. An iteration may require several FE analyses. Spacing and geometry limits remain binding; the target may not be achievable. Uploaded fixed positions are not optimised.

Target values

Maximum pile load N_max [kN] Max. influence area A_max [m²]

Optimization

Minimum pile spacing [m] Max. tangential spacing [m] Number of rings, 0 = automatic Max. rings in search Max. equal ring count Start inside min. piles Start inside max. piles Start with one pile in the center Offset adjacent rings

Display

Draw square piles Draw influence areas Label influence area Show pile numbers Label position at pile Ring number factor First ring number First pile number per ring

Result

FE optimisation – progress

Target deviation reached

Completed iterations0 / 10

Maximum deviation from mean0.229 %

Target: maximum load deviation from mean [%]1.000 %

Pile loads min. / mean / max.391.800 / 392.699 / 393.486 kN

Difference max. − min.1.686 kN

Completed FE analyses1

Tributary areas and their loads still describe the initial geometric layout. FE spring reactions govern for the moved piles.

Ring sequence8-8-16-16-32

Number of piles80

Area per pile3.927 m²

Load per pile393.486 kN

Total load31415.927 kN

Total area314.159 m²

Min. spacing1.614 m

FE mesh1025 nodes / 1024 elements

Max. |w|3.998 mm

Spring reactions391.8–393.5 kN

Max. concrete tensile stress0.218 MPa

Max. |m|35.866 kNm/m

FE equilibrium0.000 %

Notes

FE model: linear-elastic Mindlin slab in uncracked state I; an inclined mid-surface is represented by local thickness, not shell action.

Export

Drawing

Interactive 3D model

Slab, indicative piles, pile names and area loads. Click or tap to stop automatic rotation and select a pile. Drag or use touch to orbit, use the wheel to zoom and the right mouse button to pan. Only “Start rotation” resumes automatic rotation.

Bending stresses in uncracked state I, not a reinforcement design. Local stresses at pile springs depend on the mesh; check mesh refinement.

Pile list

No.	Ring	i	x [m]	y [m]	r [m]	Angle [°]	A [m²]	Tributary N [kN]	FE N [kN]	FE w [mm]	s arc [m]	s chord [m]
101	1	1	2.108	0.000	2.108	0.00	3.927	392.699	392.579	3.926	1.656	1.614
102	1	2	1.491	1.491	2.108	45.00	3.927	392.699	392.579	3.926	1.656	1.614
103	1	3	0.000	2.108	2.108	90.00	3.927	392.699	392.579	3.926	1.656	1.614
104	1	4	-1.491	1.491	2.108	135.00	3.927	392.699	392.579	3.926	1.656	1.614
105	1	5	-2.108	0.000	2.108	180.00	3.927	392.699	392.579	3.926	1.656	1.614
106	1	6	-1.491	-1.491	2.108	225.00	3.927	392.699	392.579	3.926	1.656	1.614
107	1	7	-0.000	-2.108	2.108	270.00	3.927	392.699	392.579	3.926	1.656	1.614
108	1	8	1.491	-1.491	2.108	315.00	3.927	392.699	392.579	3.926	1.656	1.614
201	2	1	3.561	1.475	3.855	22.50	3.927	392.699	392.231	3.922	3.027	2.950
202	2	2	1.475	3.561	3.855	67.50	3.927	392.699	392.231	3.922	3.027	2.950
203	2	3	-1.475	3.561	3.855	112.50	3.927	392.699	392.231	3.922	3.027	2.950
204	2	4	-3.561	1.475	3.855	157.50	3.927	392.699	392.231	3.922	3.027	2.950
205	2	5	-3.561	-1.475	3.855	202.50	3.927	392.699	392.231	3.922	3.027	2.950
206	2	6	-1.475	-3.561	3.855	247.50	3.927	392.699	392.231	3.922	3.027	2.950
207	2	7	1.475	-3.561	3.855	292.50	3.927	392.699	392.231	3.922	3.027	2.950
208	2	8	3.561	-1.475	3.855	337.50	3.927	392.699	392.231	3.922	3.027	2.950
301	3	1	5.347	1.063	5.451	11.25	3.927	392.699	391.800	3.918	2.141	2.127
302	3	2	4.533	3.029	5.451	33.75	3.927	392.699	391.800	3.918	2.141	2.127
303	3	3	3.029	4.533	5.451	56.25	3.927	392.699	391.800	3.918	2.141	2.127
304	3	4	1.063	5.347	5.451	78.75	3.927	392.699	391.800	3.918	2.141	2.127
305	3	5	-1.063	5.347	5.451	101.25	3.927	392.699	391.800	3.918	2.141	2.127
306	3	6	-3.029	4.533	5.451	123.75	3.927	392.699	391.800	3.918	2.141	2.127
307	3	7	-4.533	3.029	5.451	146.25	3.927	392.699	391.800	3.918	2.141	2.127
308	3	8	-5.347	1.063	5.451	168.75	3.927	392.699	391.800	3.918	2.141	2.127
309	3	9	-5.347	-1.063	5.451	191.25	3.927	392.699	391.800	3.918	2.141	2.127
310	3	10	-4.533	-3.029	5.451	213.75	3.927	392.699	391.800	3.918	2.141	2.127
311	3	11	-3.029	-4.533	5.451	236.25	3.927	392.699	391.800	3.918	2.141	2.127
312	3	12	-1.063	-5.347	5.451	258.75	3.927	392.699	391.800	3.918	2.141	2.127
313	3	13	1.063	-5.347	5.451	281.25	3.927	392.699	391.800	3.918	2.141	2.127
314	3	14	3.029	-4.533	5.451	303.75	3.927	392.699	391.800	3.918	2.141	2.127
315	3	15	4.533	-3.029	5.451	326.25	3.927	392.699	391.800	3.918	2.141	2.127
316	3	16	5.347	-1.063	5.451	348.75	3.927	392.699	391.800	3.918	2.141	2.127
401	4	1	7.059	0.000	7.059	0.00	3.927	392.699	392.345	3.923	2.772	2.754
402	4	2	6.522	2.701	7.059	22.50	3.927	392.699	392.308	3.923	2.772	2.754
403	4	3	4.992	4.992	7.059	45.00	3.927	392.699	392.345	3.923	2.772	2.754
404	4	4	2.701	6.522	7.059	67.50	3.927	392.699	392.308	3.923	2.772	2.754
405	4	5	0.000	7.059	7.059	90.00	3.927	392.699	392.345	3.923	2.772	2.754
406	4	6	-2.701	6.522	7.059	112.50	3.927	392.699	392.308	3.923	2.772	2.754
407	4	7	-4.992	4.992	7.059	135.00	3.927	392.699	392.345	3.923	2.772	2.754
408	4	8	-6.522	2.701	7.059	157.50	3.927	392.699	392.308	3.923	2.772	2.754
409	4	9	-7.059	0.000	7.059	180.00	3.927	392.699	392.345	3.923	2.772	2.754
410	4	10	-6.522	-2.701	7.059	202.50	3.927	392.699	392.308	3.923	2.772	2.754
411	4	11	-4.992	-4.992	7.059	225.00	3.927	392.699	392.345	3.923	2.772	2.754
412	4	12	-2.701	-6.522	7.059	247.50	3.927	392.699	392.308	3.923	2.772	2.754
413	4	13	-0.000	-7.059	7.059	270.00	3.927	392.699	392.345	3.923	2.772	2.754
414	4	14	2.701	-6.522	7.059	292.50	3.927	392.699	392.308	3.923	2.772	2.754
415	4	15	4.992	-4.992	7.059	315.00	3.927	392.699	392.345	3.923	2.772	2.754
416	4	16	6.522	-2.701	7.059	337.50	3.927	392.699	392.308	3.923	2.772	2.754
501	5	1	8.878	0.874	8.921	5.62	3.927	392.699	393.486	3.935	1.752	1.749
502	5	2	8.537	2.590	8.921	16.88	3.927	392.699	393.478	3.935	1.752	1.749
503	5	3	7.867	4.205	8.921	28.12	3.927	392.699	393.478	3.935	1.752	1.749
504	5	4	6.896	5.659	8.921	39.38	3.927	392.699	393.486	3.935	1.752	1.749
505	5	5	5.659	6.896	8.921	50.62	3.927	392.699	393.486	3.935	1.752	1.749
506	5	6	4.205	7.867	8.921	61.87	3.927	392.699	393.478	3.935	1.752	1.749
507	5	7	2.590	8.537	8.921	73.12	3.927	392.699	393.478	3.935	1.752	1.749
508	5	8	0.874	8.878	8.921	84.38	3.927	392.699	393.486	3.935	1.752	1.749
509	5	9	-0.874	8.878	8.921	95.62	3.927	392.699	393.486	3.935	1.752	1.749
510	5	10	-2.590	8.537	8.921	106.88	3.927	392.699	393.478	3.935	1.752	1.749
511	5	11	-4.205	7.867	8.921	118.12	3.927	392.699	393.478	3.935	1.752	1.749
512	5	12	-5.659	6.896	8.921	129.38	3.927	392.699	393.486	3.935	1.752	1.749
513	5	13	-6.896	5.659	8.921	140.62	3.927	392.699	393.486	3.935	1.752	1.749
514	5	14	-7.867	4.205	8.921	151.88	3.927	392.699	393.478	3.935	1.752	1.749
515	5	15	-8.537	2.590	8.921	163.12	3.927	392.699	393.478	3.935	1.752	1.749
516	5	16	-8.878	0.874	8.921	174.38	3.927	392.699	393.486	3.935	1.752	1.749
517	5	17	-8.878	-0.874	8.921	185.62	3.927	392.699	393.486	3.935	1.752	1.749
518	5	18	-8.537	-2.590	8.921	196.88	3.927	392.699	393.478	3.935	1.752	1.749
519	5	19	-7.867	-4.205	8.921	208.12	3.927	392.699	393.478	3.935	1.752	1.749
520	5	20	-6.896	-5.659	8.921	219.38	3.927	392.699	393.486	3.935	1.752	1.749
521	5	21	-5.659	-6.896	8.921	230.62	3.927	392.699	393.486	3.935	1.752	1.749
522	5	22	-4.205	-7.867	8.921	241.88	3.927	392.699	393.478	3.935	1.752	1.749
523	5	23	-2.590	-8.537	8.921	253.12	3.927	392.699	393.478	3.935	1.752	1.749
524	5	24	-0.874	-8.878	8.921	264.37	3.927	392.699	393.486	3.935	1.752	1.749
525	5	25	0.874	-8.878	8.921	275.62	3.927	392.699	393.486	3.935	1.752	1.749
526	5	26	2.590	-8.537	8.921	286.88	3.927	392.699	393.478	3.935	1.752	1.749
527	5	27	4.205	-7.867	8.921	298.12	3.927	392.699	393.478	3.935	1.752	1.749
528	5	28	5.659	-6.896	8.921	309.37	3.927	392.699	393.486	3.935	1.752	1.749
529	5	29	6.896	-5.659	8.921	320.62	3.927	392.699	393.486	3.935	1.752	1.749
530	5	30	7.867	-4.205	8.921	331.88	3.927	392.699	393.478	3.935	1.752	1.749
531	5	31	8.537	-2.590	8.921	343.12	3.927	392.699	393.478	3.935	1.752	1.749
532	5	32	8.878	-0.874	8.921	354.37	3.927	392.699	393.486	3.935	1.752	1.749