CivilTech Studio — Structural Engineering Tools

Overview

Getting started

CivilTech Studio is a browser-based structural engineering toolkit. Every module runs in your browser for deterministic checks and proxies to our compute engines for the heavier work (FEM, site optimization, DXF rendering).

Email + password — no credit card required. The Free tier starts at 10 credits/month.

Verify

Click the link in your verification email. Students / academics can also upload an ID to unlock tier-specific perks.

Pick a module

Tools are organised by discipline — foundation, basement, mix, geotech, section, steel.

Enter inputs

The form auto-adjusts to the code you select (IS / ACI / EC2 / AISC).

Run the design

Deterministic checks are instant. Heavy runs (FEM, site-opt) spin up the compute engine.

Export

PDF, DXF, BBS — all from the same page. Credits are only deducted for paid exports.

Start with Foundation Design Sign up (Free) See pricing

Overview

How it runs

Most of CivilTech Studio’s calculations run in your browser — deterministic code checks, validations, diagrams. Heavy lifting (optimization, FEM, CAD generation) is delegated to purpose-built compute engines behind authenticated API routes.

Browser (client)

· Input forms, unit conversion, validation
· Single-footing deterministic checks
· BBS Excel/PDF serialisation
· Diagrams: placement, P-M, rebar cage, section

Server (compute)

· Python + C++ IntelliCascade™ engine (Docker)
· FEM solver (sparse LU, Mindlin plates)
· .NET DXF renderer for AutoCAD-compatible drawings
· Next.js API routes proxy + gate credits

Each paid endpoint enforces credit deduction before calling the engine; see Credits & pricing.

Reference

Design codes coverage

CivilTech Studio cross-checks every design against the code you select. Coverage is version-specific — we update the engine as amendments are published.

Code	Version	Scope	Used in
IS 456	2000 (+amendments)	RCC design & detailing	Foundation, Basement, Section
IS 3370	Parts 1-4 (2021)	Water-retaining structures	Basement
IS 1893	2016	Seismic loads / liquefaction	Geotechnical
IS 6403	1981 (R2002)	Bearing capacity	Geotechnical
IS 10262	2019	Concrete mix design	Mix Design
IS 800	2007	Steel (LSM)	Steel Section
ACI 318	2019	RCC design & detailing (USA)	Foundation, Section, Basement
ACI 211.1	-91 (R2009)	Mix design	Mix Design
AISC 360	2016	Steel (LRFD/ASD)	Steel Section
Eurocode 2	EN 1992-1-1 (2004)	RCC design	Foundation, Basement, Section
Eurocode 3	EN 1993-1-1 (2005)	Steel design	Steel Section
BS 8500 / EN 206	2015	Concrete mix durability	Mix Design

Don’t see your code? Enterprise plans include adding region-specific codes; contact sales from the Pricing page.

Overview

Credits & pricing

You pay for compute, not features. Every tier gets the full tool-set; what differs is how much server compute your month covers.

Action	Credits
Single-column / deterministic design	FREE
IntelliCascade™ sequential (per-column fast solve)	FREE
Unified 5-layer pipeline	FREE
Site optimization (per column)	0.2/col · min 1
FEM analysis	1
Engineer PDF report	1
DXF export (site plan / basement)	2
BBS Excel / PDF export	1

See the full pricing page for the credit calculator and tier comparison.

Reference

Modules

Foundation Design

IS 456 · ACI 318 · Eurocode 2 · IntelliCascade™

Open module

Isolated footing design across five footing types with automatic progression from the cheapest to the most capable. The engine solves for bearing, one-way and two-way shear, flexure, development length and settlement, then emits reinforcement and a bar bending schedule.

IS 456:2000ACI 318-19Eurocode 2 (EN 1992-1-1)

Cascade logic \u2014 stops at first passing design

Cheapest to try firstMost capable (deep foundation)Algorithm stops at the first design that passes all 9 checks.

In plain English

Most tools make you pick the footing type and then check if it works. IntelliCascade flips that \u2014 it tries every type in order of cost(pad \u2192 sloped \u2192 stepped \u2192 combined \u2192 raft \u2192 pile) and stops at the first one that passes all the design checks. You always get the cheapest design that's safe for your loads and soil.

\u2192 Like: ordering off a menu \u2014 we pick the simplest dish that fills you up; if it won't, we upgrade step by step until one does.

Figure\u2002\u00b7\u2002IntelliCascade\u2122 progression \u2014 six footing strategies tried in order of cost, stopping at the first that clears every design check.

Bearing pressure distribution

e = 0.0% \u00d7 L (kern = L/6 \u2248 16.67%)

Eccentricity:

Uniform pressure

q = P / A — even load, flat distribution.

In plain English

When the load sits dead-centre on a footing, the soil pushes back evenly. When it sits off-centre (eccentric), pressure piles up on one edge. Go too far off-centre and the other edge actually lifts off the soil \u2014 the engine catches that (called "uplift") and re-solves on the reduced contact area.

\u2192 Like: standing on a sponge \u2014 stand dead-centre and it squishes evenly; lean to one side and one edge digs in hard while the other lifts off.

Figure\u2002\u00b7\u2002Interactive bearing-pressure distribution. Drag the slider to move eccentricity across the kern boundary (L/6).

Two-way (punching) shear

In plain English

A heavy column can literally punch a hole down through the footingif the footing is too thin. The failure surface fans outward at roughly 45\u00b0, so codes check the stress on a rectangle (the cyan dashed line) that sits one half-depth (d/2) outside the column face. Pass this check and the column stays put; fail it and you need a thicker footing.

\u2192 Like: punching your fist through a sheet of cardboard \u2014 the hole is bigger than your fist, because the tear fans out at an angle.

Figure\u2002\u00b7\u2002Punching-shear failure envelope around a column. The cyan critical perimeter (b\u2080) sits at d/2 from each column face per IS 456 Cl. 31.6 / ACI 318 \u00a722.6.5.

What it calculates

Safe bearing pressure vs applied pressure at service and factored loads
One-way & two-way (punching) shear with tier-2 code clauses
Flexural reinforcement (both directions) with minimum / maximum steel limits
Development length with IS 456 / ACI 318 / EC2 anchorage rules
Elastic settlement (immediate) and consolidation settlement where inputs allow
Reinforcement detailing: spacing, cover, hook geometry per code

Inputs

Column: size, axial load P, moments Mx/My, shear (optional)
Soil: allowable bearing, modulus, density, water table depth
Materials: concrete grade fck, steel grade fy
Depth of footing, cover, rebar diameter range

Outputs

Chosen footing type + dimensions (pad, sloped, stepped, combined, strap, raft, or pile) with step offsets for stepped, pile-cap schedule for pile, strap beam detail for strap
Reinforcement schedule with bar marks, diameter, spacing, cutting lengths
Check summary (all 9 design checks pass/fail with ratios)
Engineer PDF report, DXF plan, BBS Excel

How to use

1Open Foundation Design → enter column loads + soil bearing.
2Pick the design code (IS / ACI / EC2). Units toggle via the nav bar.
3Run IntelliCascade™ — it cascades through pad → sloped → stepped → combined → raft → pile, stopping at the first footing that passes all 9 checks.
4Review the chosen design on the left panel; the placement diagram + BBS render automatically.
5Export: PDF for the full calc, DXF for the drawing, BBS Excel for the detailer.

Key formulas

Factored area required

A_req = P / (q_a × γ)

IS 456 Cl. 34

Two-way (punching) shear stress

τ_v = V_u / (b_o × d)

IS 456 Cl. 31.6 / ACI 22.6.5

One-way shear stress

τ_c,1 = V_u / (b × d)

IS 456 Cl. 40.1

Development length

L_d = φ × σ_s / (4 × τ_bd)

IS 456 Cl. 26.2.1

Punching permissible

k_s × τ_c = (0.5 + β_c) × 0.25√fck

IS 456 Cl. 31.6.3

Limitations & scope

·Single-column Foundation Design cascades pad → sloped → stepped → combined → raft → pile automatically. Two-column strap/combined layouts are exposed in Batch mode, and site-wide multi-column optimisation is in Site mode.
·Soil input accepts scalar allowable bearing (plus modulus for settlement); layered profiles are processed by the layered-soil envelope (Meyerhof 2:1 stress-spread with weakest-layer projection).
·Dynamic/seismic amplification must be pre-factored into the column loads — the module does not run IS 1893 / ASCE 7 response spectra.

Troubleshooting

All footings fail punching shear

Increase effective depth (d) or step up to stepped/sloped; check concrete grade ≥ M25 for large loads.

Steel over 4% reported

Section is over-reinforced. Enlarge plan dimensions (L × B) so required Ast drops below the 4% ceiling.

Settlement > L/500

Revisit soil modulus E_s — allowable bearing alone does not prevent settlement failure.

IntelliCascade™ cascade order FEM verification for irregular loads Site-plan optimization (many columns)

Single-column design is always free — no credits are charged even on the Free tier.

IntelliCascade™ stops at the first footing that passes all 9 checks, so downstream types only run when needed.

FREE — deterministic cascade, single column

Basement Design

IS 456 / IS 3370 · ACI 318 · Eurocode 2

Open module

Retaining-wall and base-slab design for basements with full water-retaining-structure provisions. Covers earth pressure, buoyancy, surcharge, crack-width control, and exports a BBS suitable for waterproof construction.

IS 456:2000IS 3370 (parts 1–4)ACI 318-19Eurocode 2

Retaining wall loads

In plain English

A basement wall has to resist three things pushing on it at once: the weight of the dirt behind it (bigger the deeper you go), water pressure if there's a water table, and any load sitting on the ground above (a parked car, a building, a stockpile). The engine computes all three and designs enough rebar on the earth-side of the wall to stop it from cracking.

\u2192 Like: a dam wall holding back a lake, but the lake is made of dirt, water, and whatever's parked on top.

Figure\u2002\u00b7\u2002Cross-section of a basement wall with the three design loads. Arrows pulse to convey continuous (not one-time) loading.

What it calculates

Active/at-rest/passive earth pressures on basement wall
Wall flexure & shear with water-retaining crack-width limits
Base slab flexure, buoyancy check (uplift), punching around columns
Anchorage, lap length, minimum reinforcement per IS 3370 limits
Surcharge distribution (strip, line, point) with Boussinesq
Seismic lateral earth pressure increment via Mononobe-Okabe (IS 1893 / ASCE 7)

Inputs

Basement depth, wall height, slab thickness
Soil: unit weight, angle of friction, cohesion, surcharge
Water-table elevation (for buoyancy + crack-width toggle)
Concrete grade, steel grade, cover to reinforcement
Seismic zone & site soil type (auto-derives ah/av for M-O)

Outputs

Wall & slab dimensions + reinforcement layout
Crack-width estimate vs allowable (0.1 – 0.2 mm per IS 3370)
Buoyancy factor-of-safety with and without dead-load anchorage
PDF calc report + BBS Excel + DXF detail

How to use

1Set basement geometry (depth, wall height, slab thickness).
2Enter soil profile and water table — the crack-width limit auto-adjusts.
3Specify column loads above slab so punching is included.
4Run design; review the governing check (usually crack width for water-retaining).
5Export the DXF detail — it includes wall reinforcement and construction joints.

Key formulas

At-rest earth pressure

K_0 = 1 − sin(φ)

Jaky 1944 / IS 14458

Active earth pressure

K_a = tan²(45° − φ/2)

Rankine

Crack width

w_cr = 3 a_cr ε_m / (1 + 2(a_cr − c_min)/(h − x))

IS 456 Annex F / IS 3370

Buoyancy FoS

FoS = (W_dead + W_soil above footing) / F_buoyancy

IS 3370-2

Limitations & scope

·Rectangular plan as the primary design path. L / T / U / general rectilinear plans are decomposed into axis-aligned bays by the basement-plan decomposer (`/basement/decompose`); each bay is designed separately and the envelope is aggregated (governing wall rebar, max slab thickness, summed dead load vs uplift). Diagonal or curved walls still need manual modelling.
·Temperature + shrinkage reinforcement is sized to IS 456 minimum; bespoke thermal restraint cases (high degree-of-restraint pours, large volume changes) should be verified separately.

Troubleshooting

Crack width exceeds 0.2 mm

Reduce bar spacing or increase bar count — crack width scales inversely with As provided.

Buoyancy FoS < 1.2

Extend the base slab toe beyond the wall line, or add anchor piles. Simply increasing slab thickness rarely helps.

Slab punching fails under column

Introduce a pedestal/column head thickening, or switch to a thicker local raft patch.

Water-retaining checks (IS 3370)DXF export cost & layer scheme

FREE to design · DXF = 2 credits · BBS = 1 credit

Concrete Mix Design

IS 10262 · ACI 211 · BS 8500 / EN 206

Open module

Proportion concrete mixes from target strength and exposure class. Produces trial mix quantities per m³, recommended w/c, cement content, coarse/fine aggregate ratio, and a nominal-mix cross-reference.

IS 10262:2019ACI 211.1-91BS 8500 / EN 206

Mix recipe & w/c strength

Typical M25 mix \u2014 by volume

48%

Coarse Aggregate

28%

Fine Aggregate

15%

Cement

Water

Admixtures

Coarse Aggregate

20 mm stone — the skeleton

Fine Aggregate

sand — fills the gaps

Cement

glues everything together

Water

activates the chemistry

Admixtures

plasticiser, retarder

Water/cement ratio

w/c = 0.45

Strength

37.3 MPa

Grade

M35

Workability

medium — good

In plain English

Concrete is a recipe. Stone and sand do the heavy lifting, cement glues it all together, and water wakes up the chemistry. The biggest lever is the water/cement ratio \u2014 less water means stronger concrete, but it's harder to pour. The engine solves this trade-off for you based on the grade your structure actually needs.

\u2192 Like: baking bread \u2014 more water = easier to knead, but the loaf comes out soft. Less water = firmer bread, but harder to mix.

Figure\u2002\u00b7\u2002Interactive mix recipe. The slider drives the classic Abrams'-law strength vs w/c curve in real time.

What it calculates

Target mean strength (fck + 1.65 σ) for the chosen grade
Water/cement ratio from durability + strength curves
Cement, water, fine aggregate, coarse aggregate quantities per m³
Admixture dosage bounds (super-plasticizer / mineral admixture)
Nominal mix equivalent (M-ratio) for on-site batching

Inputs

Target grade (M20 / M25 / … / M80 or ACI ksi / EN class)
Exposure condition (mild / moderate / severe / very severe / extreme)
Aggregate nominal max size, specific gravity, workability target
Cement type (OPC 43 / 53 / PPC / PSC) or ACI cement class

Outputs

Material quantities per m³ of concrete
Recommended slump and admixture range
PDF mix report + Excel quantity sheet

How to use

1Pick the code, grade, exposure class — the page re-flows inputs to what that code needs.
2Enter material specifics (cement type, aggregate size, slump target).
3Generate the mix — the ratio card updates live.
4Download the PDF report for site submission or Excel for batching.

Key formulas

Target mean strength

f_ck,target = f_ck + 1.65 × σ

IS 10262 Cl. 4

Water content (saturated)

W = 186 kg/m³ (20 mm MSA, slump 50 mm)

IS 10262 Table 4

Cement content

C = W / (w/c)

IS 10262 Cl. 5.3

Fine aggregate %

FA% = depends on zone + W/C

IS 10262 Table 5

Limitations & scope

·Self-compacting concrete (SCC) and fibre-reinforced mixes are not directly covered — run as a base mix then add admixture trial separately.
·Does not predict slump loss over time; site transport corrections are the engineer’s call.
·Aggregate absorption / specific gravity must be measured — don’t rely on default 2.65 for lightweight or heavyweight aggregate.

Troubleshooting

Cement content exceeds 450 kg/m³

Usually means you’re chasing high strength with low-grade cement. Switch to OPC 53 or add fly-ash/GGBS to stay within durability limits.

Admixture dosage > 2%

Reduce water-cement ratio requirement, or use a newer PCE super-plasticizer. 2% is typically the practical ceiling.

PDF report credit cost

FREE · PDF report = 1 credit

Geotechnical Analysis

IS 6403 · Terzaghi · Meyerhof · Seed-Idriss

Open module

SPT-driven soil analysis for bearing capacity and liquefaction risk. Correlates N-values to safe bearing, cross-checks against four code methods, and screens layered profiles for seismic liquefaction per IS 1893 and NCEER.

IS 6403IS 1893TerzaghiMeyerhofBowlesNCEER

Bearing pressure distribution

e = 0.0% \u00d7 L (kern = L/6 \u2248 16.67%)

Eccentricity:

Uniform pressure

q = P / A — even load, flat distribution.

In plain English

\u2192 Like: standing on a sponge \u2014 stand dead-centre and it squishes evenly; lean to one side and one edge digs in hard while the other lifts off.

Figure\u2002\u00b7\u2002Interactive bearing-pressure distribution. Drag the slider to move eccentricity across the kern boundary (L/6).

What it calculates

Corrected SPT N-values (overburden, hammer efficiency, borehole dia)
CPT-based bearing capacity (Meyerhof + De Beer) with Robertson (1990) soil classification and Schmertmann settlement
Rock bearing via RMR + RQD + Hoek-Brown criterion for weaker rock masses
Ultimate + safe bearing capacity from 4 correlations + code checks
Liquefaction CSR vs CRR with FS, ground-surface PGA, and mitigation recommendations (densification, stone columns, grouting)
Post-liquefaction reconsolidation settlement: Ishihara-Yoshimine (1992) bilinear-chart εv plus Tokimatsu-Seed (1987) envelope, aggregated to ground-surface subsidence
Layered-soil SBC envelope: per-layer intrinsic SBC projected to footing level via Meyerhof 2:1 stress-spread, with the weakest attenuated layer governing
Soil classification (IS / USCS) per plasticity and gradation inputs
Differential settlement estimate for layered profiles

Inputs

Borehole log (SPT): depth, N-value, moisture, UCS/plasticity per layer
Cone Penetration Test (CPT) sounding: depth intervals with qc and fs — routed through Robertson (1990) SBT classification + Meyerhof / De Beer bearing correlations
Rock profile: RQD, UCS, joint spacing, weathering — for RMR-based rock bearing
Groundwater elevation, design PGA, magnitude (for liquefaction)
Footing size + embedment (drives the bearing calc)

Outputs

SBC envelope across all four methods
Layer-wise liquefaction FS chart with pass/fail zones
PDF geotechnical report

How to use

1Enter borehole layers top-to-bottom — the preview updates per layer.
2Toggle liquefaction check to switch on seismic inputs (PGA + magnitude).
3Set footing size/embedment; SBC is computed per method and the lowest is used as the design value.
4Export PDF — the liquefaction stick-plot is included.

Key formulas

Corrected N (overburden)

N₁₆₀ = N × C_N × C_E × C_B × C_S × C_R

IS 1893 Cl. 3.18

Terzaghi ultimate bearing

q_u = c·N_c + q·N_q + 0.5·γ·B·N_γ

Terzaghi (1943)

Meyerhof SBC from SPT

q_a = 0.098 × N × (B+0.3)²/B² × FS

Meyerhof (1956)

Cyclic Stress Ratio

CSR = 0.65 × (a_max/g) × (σ_v/σ_v′) × r_d

Seed-Idriss / NCEER

Limitations & scope

·Rock bearing uses RMR/RQD correlations with Hoek-Brown screening; for mass concrete seated on rock, a dedicated geological report is still mandatory.
·Liquefaction screening includes mitigation recommendations and post-liquefaction reconsolidation settlement via both Tokimatsu-Seed (1987) and Ishihara-Yoshimine (1992) — engineers should still cross-check with CPT-based εv methods (Zhang-Robertson) for sites with dense CPT coverage.

Troubleshooting

SBC values differ widely across methods

Expected — Terzaghi is conservative, Meyerhof less so. Take the lowest as design and note the spread in your report.

Liquefaction FS just under 1

Consider ground improvement (vibro-compaction, stone columns) or shift to deep foundations bypassing the liquefiable layer.

Feed SBC into Foundation Design

FREE · PDF report = 1 credit

Section Design

IS 456 · ACI 318 · Eurocode 2 · Beam & Column

Open module

RCC section checks for beams and columns. Flexure + shear + torsion for beams, P-M interaction diagrams and biaxial bending for columns, with crack-width verification on the service-load side.

IS 456:2000ACI 318-19Eurocode 2

Beam bending behaviour

In plain English

When a beam carries a load, its top fibre squeezes and its bottom fibre stretches. Concrete is great at being squeezed but terrible at being stretched \u2014 so we add steel rebar on the stretching side to handle that force. Stirrups (the vertical loops) stop the beam from splitting along its length.

\u2192 Like: breaking a stick over your knee \u2014 the top fibre squeezes, the bottom fibre snaps. We reinforce the side that would snap.

Figure\u2002\u00b7\u2002Beam under load. Blue top = compression zone; red bottom = tension zone. The dashed line in the middle (neutral axis) sees zero stress.

What it calculates

Singly / doubly reinforced beam flexural capacity
Shear capacity with Vc + Vs contributions and stirrup design
Torsional reinforcement (closed stirrups + longitudinal bars)
P-M interaction diagram (uniaxial and biaxial)
Crack width at service load per IS 456 Annex F / EC2
Slenderness check with moment magnifiers
Fire-resistance tabular method (EC2 1-2 / IS 456 Annex E): beam (SS + continuous), column, and solid slab with axis-distance check for R30–R240

Inputs

Section geometry (b, h, cover), reinforcement layout
Service & factored loads (P, M, V, T, ecc.)
Concrete + steel grades, unbraced length

Outputs

Pass/fail matrix with utilisation ratio per check
P-M diagram (PNG + vector in PDF)
PDF calc sheet with all intermediate values

How to use

1Pick element type (beam or column).
2Enter section, reinforcement, and loads.
3Run checks — utilisation ratios flash red over 1.0.
4For columns, rotate the P-M diagram to inspect both axes; biaxial pass is shown by the 3D surface intercept.

Key formulas

Limit flexural moment (singly reinforced)

M_u,lim = 0.36 × f_ck × b × x_u × (d − 0.42 x_u)

IS 456 Annex G

Shear capacity (concrete)

V_c = τ_c × b × d

IS 456 Table 19

Biaxial interaction (columns)

(M_ux/M_ux1)^αn + (M_uy/M_uy1)^αn ≤ 1

IS 456 Cl. 39.6

Crack width (beam)

w_cr = (3 a_cr ε_m)/(1 + 2(a_cr − c_min)/(h − x))

IS 456 Annex F

Limitations & scope

·FRC (fibre-reinforced concrete): singly-reinforced rectangular sections use the fib MC 2010 residual-tensile block (fR1k, fR3k inputs). Complex geometries / combined P-M should still be verified with full σ-ε strain-compatibility.
·Prestressed concrete: simply-supported rectangular pretensioned beams are supported (transfer + service stress check + ultimate moment). Post-tensioning profiles, harped tendons, and time-step loss analysis are not yet included.
·P-Δ amplification is computed via the AISC Appendix 8 B1/B2 closed-form method, suitable when the story stability index ΣPr/ΣPe < 0.4. More flexible frames need direct second-order FEM analysis.
·Fire resistance uses only the EC2 1-2 / IS 456 Annex E tabular method — for bespoke cases or non-standard cross-sections, run the isotherm-500 °C calculation method (EC2 1-2 §4.2) with thermal analysis offline.
·No fatigue checks — treat fatigue-governed members per specialist codes.

Troubleshooting

Doubly-reinforced needed but you want singly

Increase b or d — M_u,lim ∝ bd². Bumping depth is cheaper than adding compression steel.

Biaxial check fails marginally

Check α_n interpolation — at low Pu/Pz, α_n → 1 (linear); raising Pu can actually help, not hurt.

Steel equivalent — IS 800 / AISC / EC3 PDF report with P-M diagram

FREE · PDF report = 1 credit

Steel Section Design

IS 800 · AISC 360 · Eurocode 3

Open module

Hot-rolled steel beam and column design. Section classification, flexure incl. lateral-torsional buckling, shear, compression buckling, and combined interaction equations. Supports AISC, IS, and EC3 with a unified input.

IS 800:2007AISC 360-16Eurocode 3 (EN 1993-1-1)

Steel section \u00b7 shape + buckling

In plain English

A steel section's shape does double duty: thick flanges (top & bottom) and a central web are placed to resist bending efficiently. But a long, slender beam can twist sideways under load \u2014 that's called lateral-torsional buckling. The design checks both whether the shape itself is "compact enough" and whether it's braced often enough to stop the twist.

\u2192 Like: a long ruler held flat on its edge \u2014 push down on the middle and it flips sideways. Thicker ruler or shorter span = no flipping.

Figure\u2002\u00b7\u2002Left: standard I-section geometry. Right: LTB failure mode \u2014 beam rotates about its axis under load when unbraced length L_b is too long.

What it calculates

Section classification (plastic / compact / semi-compact / slender)
Flexural strength with LTB reduction for unrestrained lengths
Compression strength per buckling curve + effective length
Shear capacity with web-slenderness check
Interaction P/Pc + Mx/Mcx + My/Mcy
Deflection estimate vs L/250 / L/300 limit
Analytical section properties for user-defined built-up I and box sections (A, Ix, Iy, Zx, Zpx, rx, ry, mass) with asymmetric-flange handling
Bolt-group design under combined shear + in-plane moment (elastic polar-moment method) with single-bolt shear/bearing/tension capacities (IS 800 Cl. 10 / AISC J3)
Fillet-weld-group elastic analysis with peak line-load and throat stress check (IS 800 Cl. 10.5 / AISC J2)
Cold-formed lipped C-section — gross + effective-width section properties and nominal axial + flexural capacities (IS 801 / AISI S100 §B2.1)

Inputs

Section: pick from IS / AISC / EC profile database
Loads, span, unbraced lengths, end conditions
Steel grade (Fe 410 / A992 / S355), partial factors

Outputs

Capacity envelope + utilisation per limit state
Deflection summary with serviceability flag
PDF calc report

How to use

1Pick the design code — the section database auto-switches.
2Type the section designation (e.g. ISMB 300, W12x26, IPE 300).
3Set the span and bracing; LTB reduction is shown live.
4Review interaction-equation output; anything > 1.0 is flagged.

Key formulas

Section classification (flange)

b/t_f ≤ 9.4ε (plastic) · 10.5ε (compact) · 15.7ε (semi-compact)

IS 800 Cl. 3.7.2

LTB reduction factor

χ_LT = 1/[Φ_LT + √(Φ_LT² − λ_LT²)]

IS 800 Cl. 8.2.2 / EC3 Cl. 6.3.2

Compression capacity

P_d = A_e × f_cd = A_e × χ × f_y/γ_m0

IS 800 Cl. 7.1.2

Combined interaction

P/P_d + C_mx·M_x/(M_dx·(1−P/P_ex)) + … ≤ 1

IS 800 Cl. 9.3

Limitations & scope

·Rolled-catalogue sections (ISMB, W-shape, HE, IPE) plus user-defined built-up I and box sections are supported. For arbitrary cross-sections (channels, tees, angles, tapered girders) run the properties externally and provide them via the override interface.
·Bolt + fillet-weld group design is included (elastic method). High-strength friction-grip (HSFG / slip-critical) and IC / plastic methods for bolt groups, plus groove welds, are not yet covered.
·Cold-formed steel coverage is limited to lipped C-sections (compression + flexure with effective-width reduction). Z-sections, hat-sections, studs, and distortional-buckling checks per IS 801 §6.4 remain out of scope.

Troubleshooting

LTB reduces capacity by > 40%

Reduce unbraced length with intermediate lateral restraints (secondary beams, bracing) — typically cheaper than upsizing the section.

Deflection passes but section looks slender

Re-check section classification with the actual flange width — slenderness controls moment capacity, not just deflection.

Concrete equivalent — Section Design

FREE · PDF report = 1 credit

Cross-cutting

Features & engines

IntelliCascade™ Engine

Patented progressive footing optimization

IntelliCascade™ tries footing types in order of cost — pad → sloped → stepped → combined → pile — and stops at the first type that passes all nine structural checks. A C++ sequential engine solves each type in ~3 s per footing on a single thread.

Cascade logic \u2014 stops at first passing design

Cheapest to try firstMost capable (deep foundation)Algorithm stops at the first design that passes all 9 checks.

In plain English

\u2192 Like: ordering off a menu \u2014 we pick the simplest dish that fills you up; if it won't, we upgrade step by step until one does.

Figure\u2002\u00b7\u2002IntelliCascade\u2122 progression \u2014 six footing strategies tried in order of cost, stopping at the first that clears every design check.

Cascade order is cost-indexed (steel + concrete volume) so cheaper types are tried first.
Each footing type owns its own check-set: e.g. combined adds eccentricity-under-column checks.
The 5-layer pipeline (Unified) runs the cascade + a final reconciliation layer that re-checks all columns against the chosen site layout.

Sequential engine (per-column fast solve) = FREE · Unified 5-layer = FREE · Site-wide optimization = metered per column

Site-Plan Optimization

Solve every column on the site in one pass

Upload a boundary polygon + up to 200 columns. The engine places, optimizes, and reconciles every footing against the site constraints (overlaps, property-line offsets, pile-cap clearance) in one run.

Site-plan layout \u00b7 boundary-aware

IsolatedCombined (merged from overlap)Column

In plain English

A single-column tool designs each footing in isolation. Real sites have dozens of columns \u2014 and if two are close, their separate footings would collide. The engine looks at the whole plan at once, detects overlaps, and merges them into combined footings. It also keeps every footing inside the property boundary so you don't accidentally design one that runs into the neighbour's plot.

\u2192 Like: laying out tiles on a floor \u2014 two small tiles that would overlap get replaced by one bigger tile that covers both.

Figure\u2002\u00b7\u2002Site-plan optimisation. Watch the two interior columns in row 2 \u2014 when their isolated footings overlap, the engine auto-merges them into a combined footing.

Supports pad, sloped, stepped, combined, pile and mat column mixing in one site.
DXF export includes layered sheets for setting-out, reinforcement, and schedule.
Cost scales linearly with column count: ceil(n × 0.2), min 1 credit. 5 cols = 1, 25 cols = 5, 50 cols = 10.

Per-column metered — 0.2 credits/column, rounded up, minimum 1

FEM Analysis

Finite-element verification for footings

For footings that need more than closed-form checks — irregular load layouts, piles with group effects, raft-style mats — a full FEM mesh is solved to give bearing-pressure heatmaps, settlement contours and rebar-stress distribution.

FEM stress contour

In plain English

Formulas tell you stress at a single critical section. FEM slices the footing into thousands of small elements and checks each one individually, then paints a colour map. Red spots reveal stress concentrations the formula might average away \u2014 especially around columns, corners, and openings.

\u2192 Like: an MRI scan of a footing \u2014 instead of one measurement, we get thousands.

Figure\u2002\u00b7\u2002FEM stress map. Each coloured square is an element; yellow dots mark a few mesh nodes. Concentric waves show how load from the column propagates.

Mesh: quadrilateral plate elements with adaptive refinement around columns.
Outputs: bearing pressure heatmap (q vs qa), settlement contours (mm), Mx/My moment surfaces.
Solver: direct sparse LU; typical solve time 2 – 20 s depending on column count.

1 credit per FEM run

Bar Bending Schedule (BBS)

Detailer-ready cutting schedule + shape codes

Every footing / wall / beam with rebar gets a BBS: bar marks, diameter, shape code (per IS 2502 / BS 8666 / ACI SP-66), numbers of bars, cutting lengths, weights and hook geometry with sufficiency ratios.

Bar-bending schedule

Mark	Shape	Dia (mm)	Nos	Cut L (mm)	Weight (kg)
B1	Straight + hooks	12	8	1920	13.6
B2	L-bar	16	6	2350	22.3
S1	Stirrup	8	24	880	8.3
TOTAL STEEL					44.2 kg

In plain English

A BBS is the work order for the rebar yard. It names every bar (B1, S1\u2026), lists how many of each, its diameter, how long to cut it, and what shape to bend it into. The engine generates one automatically from your design so the detailer, estimator, and site engineer all read from the same sheet.

\u2192 Like: a shopping list with bending instructions \u2014 'six 16mm bars, each 2.35 m, bent into an L'.

Figure\u2002\u00b7\u2002Three common bar shapes with their cutting-length formulas and the schedule table they feed into.

Shape codes: 00 (straight), 11 (L-hook), 21 (cranked), 37 (U / hairpin), 51 (closed link), and more.
Hook geometry computed per the active code — R, bend angle and tail length.
Export formats: Excel (two-sheet: schedule + summary) or PDF (with shape icons + placement diagram).

1 credit per export (Excel or PDF)

DXF Export

AutoCAD-ready drawings with layers, dimensions, blocks

A dedicated .NET DXF engine emits drawings with proper DIMSTYLE, LTYPE, layers (one per rebar size + one per dimension family), reusable blocks, and engineering annotations. Opens cleanly in AutoCAD, BricsCAD, DraftSight.

Layer scheme matches CAD best-practice: SETOUT, REINFT-T12, REINFT-T16, DIMS-PLAN, etc.
Full-set export zips multiple sheets (plan, section, reinforcement elevation, schedule).
Single-file export is still a single .dxf — suitable for quick marker-ups.

2 credits per export (single or full set)

Engineer PDF Report

Full-length calc report — every figure, every intermediate

The PDF is not a screenshot pack — it is a full vector-math report with the governing equations, code clauses, intermediate values, diagrams, and the bar bending schedule, suitable for submission to a reviewing engineer or jurisdiction.

Per-module templates: foundation, basement, section, mix, geotech, steel.
Figures are vector (infinite zoom) — P-M diagrams, placement sections, FEM heatmaps.
Branding: custom logo + brand color available on Pro+ tiers.

1 credit per report

Water-Retaining Checks

IS 3370 crack-width for basements, tanks, retaining walls

Where water retention matters, the design side automatically switches in IS 3370 (or EC2 Annex H) crack-width limits — 0.1 mm uncoated reinforcement in Class I, 0.2 mm in Class II.

Triggered automatically in Basement Design when water-table > slab bottom.
Crack-width formula: Annex F of IS 456 cross-checked against IS 3370 limits.

No extra cost — included in the relevant module

Help

FAQ & troubleshooting

Which code should I pick if the project is in India?

Default to IS 456 for concrete and IS 800 for steel. Use ACI or EC2 only if your project contractually requires them (international specifications, foreign consultant review).

Why does my site-optimization run cost variable credits?

Because it runs one optimization per column. Cost scales as ceil(n × 0.2), minimum 1 — a 5-column site costs 1 credit, a 50-column site costs 10 credits.

Do I lose credits if the engine fails?

Credits are deducted before the compute engine is called. If the engine errors out (rare — typical uptime is 99.9%), contact support with the request ID shown in the error screen and we refund manually.

How do I switch between units (SI / Imperial)?

The unit toggle lives in the top nav bar inside every module. Your preference is saved locally and respected across modules.

Can I use exported DXFs with BricsCAD, DraftSight, or ZWCAD?

Yes — we target the AutoCAD 2018 DXF format, which is the de-facto standard all mainstream CAD tools open without conversion.

Is the BBS acceptable for site execution?

The Excel BBS carries bar marks, diameters, cutting lengths, hook geometry and shape codes per IS 2502 / BS 8666 / ACI SP-66. It is identical in form to what bar-benders use on site; the sufficiency ratios flag any inadequate hook geometry automatically.

How do I get help?

From the Help section on the landing page — documentation card (this page), feature request, bug report, and community links. Subscribers get priority email support; enterprise customers get a dedicated account manager.

Done reading?

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FAQ & troubleshooting

Which code should I pick if the project is in India?

Why does my site-optimization run cost variable credits?

Do I lose credits if the engine fails?

How do I switch between units (SI / Imperial)?

Can I use exported DXFs with BricsCAD, DraftSight, or ZWCAD?

Is the BBS acceptable for site execution?

How do I get help?

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