TS 500 / TBDY 2018 Structural Design Guide
Quick-reference for concrete design per TS 500:2000, seismic design per TBDY 2018 (Turkish Building Earthquake Code), load combinations per TS 498, and ductile detailing.
1.1 Concrete — TS 500:2000 Table 2.1
Design compressive strength: fcd = 0.85·fck/γc (γc = 1.5) → fcd = 0.567·fck
Modulus of elasticity: Ec = 3250·√fck + 14000 (MPa)
| Class | fck (MPa) | fcd (MPa) | fctk (MPa) | fctd (MPa) | Ec (MPa) |
|---|---|---|---|---|---|
| C16 | 16 | 9.1 | 1.40 | 0.93 | 27,000 |
| C20 | 20 | 11.3 | 1.60 | 1.07 | 28,500 |
| C25 | 25 | 14.2 | 1.80 | 1.20 | 30,250 |
| C30 | 30 | 17.0 | 1.90 | 1.27 | 31,820 |
| C35 | 35 | 19.8 | 2.10 | 1.40 | 33,230 |
| C40 | 40 | 22.7 | 2.20 | 1.47 | 34,520 |
| C45 | 45 | 25.5 | 2.40 | 1.60 | 35,760 |
| C50 | 50 | 28.3 | 2.50 | 1.67 | 36,970 |
fctd = fctk/1.5. TBDY 2018 Madde 7.2.2: minimum C25 for YDMÇ/YDPB (high ductility systems); C20 minimum for SDMÇ/SDPB.
See Concrete Properties Reference for full class properties.
1.2 Reinforcing Steel — TS 500:2000
Design yield strength: fyd = fyk/γs (γs = 1.15). Es = 200,000 MPa.
| Grade | fyk (MPa) | fyd (MPa) | Type | Seismic use |
|---|---|---|---|---|
| S220 | 220 | 191 | Plain bars (Class I) | Not permitted for primary seismic |
| S420 | 420 | 365 | Deformed (Class II) | SDMÇ acceptable |
| B420C | 420 | 365 | Deformed — seismic grade C | YDMÇ / YDPB required |
| B500C | 500 | 435 | Deformed — seismic grade C | YDMÇ / YDPB required |
TBDY 2018 Madde 7.2.3: B420C or B500C mandatory for primary seismic elements in high ductility (YDMÇ/YDPB) systems.
→ Rebar Properties & Bar Size Reference
1.3 Partial Safety Factors
| Material | γ (ULS) |
|---|---|
| Concrete (γc) | 1.50 |
| Reinforcing steel (γs) | 1.15 |
2.1 Seismic Design Class (DTS — Deprem Tasarım Sınıfı)
TBDY 2018 Table 3.4 — DTS is determined from design spectral acceleration SDS and Building Use Category (BKS):
| SDS | BKS 1 & 2 | BKS 3 & 4 |
|---|---|---|
| SDS ≥ 0.75 | DTS 1 | DTS 1a |
| 0.33 ≤ SDS < 0.75 | DTS 2 | DTS 2a |
| SDS < 0.33 | DTS 3 | DTS 4 |
BKS 1 = critical (hospitals, emergency) · BKS 2 = important (schools, high-occupancy) · BKS 3 = normal (residential, office) · BKS 4 = low risk (storage, agriculture)
2.2 Required Ductility Level by DTS
| DTS | Minimum Required System |
|---|---|
| DTS 1, 1a | Yüksek Süneklik (YDMÇ or YDPB) — High ductility only |
| DTS 2, 2a | YDMÇ or SDMÇ (High or Limited ductility acceptable) |
| DTS 3 | YDMÇ, SDMÇ, or YDPB/SDPB |
| DTS 4 | No seismic ductility detailing required |
2.3 Response Modification Factor (R) — TBDY 2018 Table 4.1
| Structural System | Ductility | R | D | I |
|---|---|---|---|---|
| RC Moment Frame (YDMÇ) | High | 8 | 3 | 3 |
| RC Moment Frame (SDMÇ) | Limited | 4 | 2.5 | 2 |
| RC Shear Wall — bearing wall (YDPB) | High | 6 | 2.5 | 2 |
| RC Shear Wall — bearing wall (SDPB) | Limited | 4 | 2 | 2 |
| Dual system — YDMÇ + YDPB | High | 7 | 2.5 | 2.5 |
| Dual system — SDMÇ + SDPB | Limited | 4 | 2 | 2 |
R = response modification factor, D = deflection amplification factor, I = overstrength factor.
2.4 Site Classes — TBDY 2018 Table 2.1
| Site Class | Description | VS30 (m/s) |
|---|---|---|
| ZA | Hard rock | > 1500 |
| ZB | Rock | 760–1500 |
| ZC | Very dense soil / soft rock | 360–760 |
| ZD | Stiff soil | 180–360 |
| ZE | Soft soil | ≤ 180 |
SDS = FSS·SS, SD1 = F1·S1 — site class amplification factors FSS and F1 from TBDY Tables 2.2 and 2.3. SS and S1 from AFAD seismic hazard maps (TDTH).
3.1 Minimum Beam Depths — TS 500:2000 Cl. 6.1.5
Recommended minimum h/L ratios for deflection control:
| Support Condition | Beam | One-way Slab |
|---|---|---|
| Simply supported | L/10 | L/30 |
| One end continuous | L/12 | L/35 |
| Both ends continuous | L/15 | L/40 |
| Cantilever | L/5 | L/12 |
These are minimum h values. Where deflection is critical, explicit calculation per TS 500 Cl. 6.5 is required.
→ Beam Flexural & Shear Design Calculator · Slab Design Calculator
3.2 Non-Seismic Minimum Dimensions
| Element | Minimum | Reference |
|---|---|---|
| Beam width bw | Practical min 200 mm | — |
| Column min dimension | Practical min 200 mm; bk/hk ≥ 0.25 | TS 500 Cl. 6.1.5 |
| Slab thickness | min 80 mm (one-way) | TS 500 Cl. 6.1.5 |
3.3 Seismic Minimum Dimensions — TBDY 2018
| Element | YDMÇ Requirement | Reference |
|---|---|---|
| Beam width bw | ≥ 250 mm; bw/h ≥ 0.3 | Madde 7.3.1 |
| Column min dimension | ≥ 300 mm; bk/hk ≥ 0.4 | Madde 7.4.1 |
| Column axial force ratio | Nd/(Ac·fcd) ≤ 0.40 (DTS 1,1a) | Madde 7.4.1 |
| Shear wall aspect ratio | hw/lw ≥ 2.0 for ductile wall | Madde 7.6.1 |
4.1 Dead Loads — TS 498 Table 2
Unit weights: RC 25 kN/m³, plain concrete 23 kN/m³, brick masonry 18–20 kN/m³, cement screed 21 kN/m³. Floor finish + screed: typically 1.0–1.5 kN/m².
4.2 Imposed Loads — TS 498 Table 3 (selected)
| Occupancy | qk (kN/m²) |
|---|---|
| Konutlar (residential) | 2.0 |
| Bürolar (office) | 3.0 |
| Sınıf, toplantı odası (classroom, meeting) | 3.0–4.0 |
| Mağaza, market (retail) | 4.0–5.0 |
| Depo, arşiv (storage) | 5.0–10.0 |
| Otopark (parking — light vehicles) | 2.5–4.0 |
4.3 Wind & Snow
Wind: TS 498 and TS EN 1991-1-4 applied in practice. Basic wind speed from Turkish national maps (Vb,0). Procedure follows EN 1991-1-4 with Turkish National Annex values.
Snow: TS 498 Table 7 / TS EN 1991-1-3. Ground snow load sk from national snow map; roof load s = μi·Ce·Ct·sk.
5.1 Earthquake Levels — TBDY 2018 Madde 2.2
| Level | Return Period | Probability (50 yr) | Design purpose |
|---|---|---|---|
| DD-1 | 2475 years | 2% | Collapse prevention (performance check) |
| DD-2 | 475 years | 10% | Standard design earthquake |
| DD-3 | 72 years | 50% | Service level (limited damage check) |
| DD-4 | 43 years | 68% | Long-period design |
Standard new building design uses DD-2 (475-year) for strength; DD-3 for interstorey drift checks.
5.2 Horizontal Design Spectrum — TBDY 2018 Madde 2.3 (DD-2)
Short-period region (0 ≤ T ≤ TA): SaR(T) = (0.4 + 0.6·T/TA)·SDS
Plateau (TA ≤ T ≤ TB): SaR(T) = SDS
Descending (TB ≤ T ≤ TL): SaR(T) = SD1/T
Long-period (T > TL): SaR(T) = SD1·TL/T²
Corner periods: TA = 0.2·TB, TB = SD1/SDS, TL = 6 s
5.3 Reduced Design Spectrum — TBDY 2018 Madde 4.3.3
Sad(T) = SaR(T) / Ra(T)
For T ≥ TB: Ra(T) = R/I (I = BKS importance factor, see Section 2.1)
For T < TB: Ra(T) = D + (R/I − D)·T/TB (linear transition)
Minimum base shear: Vt,min = 0.04·mt·SDS·g — Madde 4.3.3.3
5.4 Base Shear & Vertical Distribution (ELF)
Vt = mt·Sad(T1) — Madde 4.3.3.2
T1 ≈ Ct·H3/4: Ct = 0.07 (RC frames), 0.05 (walls/other)
Storey forces: Fi = Vt·(mi·Hiα) / Σ(mj·Hjα) — Madde 4.3.4
α = 1.0 (T1 ≤ 0.5 s), α = 2.0 (T1 ≥ 2.0 s), linear interpolation between.
Additional top storey force: ΔFN = 0.07·T1·Vt (if T1 > 0.7 s) — Madde 4.3.4
6.1 ULS Strength Combinations — TBDY 2018 Madde 4.4.3
| Combination | Equation |
|---|---|
| G1 | 1.4G |
| G2 | 1.2G + 1.6Q + 0.5(Qa or S) |
| G3 | 1.2G + 1.6(Qa or S) + max(0.5Q, 0.8W) |
| G4 | 1.2G + 1.6W + 0.5Q + 0.5(Qa or S) |
| G5 | 1.2G + 1.0Ed + 1.0Q + 0.3S |
| G6 | 0.9G + 1.6W |
| G7 | 0.9G + 1.0Ed |
G = dead load, Q = live load, Qa = roof live load, S = snow, W = wind, Ed = seismic design force. Identical load factors apply regardless of unit system.
6.2 Seismic Mass
mt = Σ(Gi + n·Qi)/g — Madde 4.4.2
n = 0.3 for residential/office occupancies; n = 0.6 for storage; n = 0 for roof live/snow.
7.1 Flexural Design — TS 500:2000 Cl. 7.1
Rectangular stress block (similar to EC2): depth factor = 0.85 for fck ≤ 30 MPa.
Normalised moment: μ = Md/(fcd·b·d²)
Mechanical reinforcement ratio: ω = 1 − √(1 − 2μ)
Required steel: As = ω·fcd·b·d / fyd
Minimum steel — TS 500 Cl. 9.3.1: As,min = 0.8·fctd·bw·d / fyd
Maximum steel — Cl. 9.3.1: ρmax = 0.85·β1·(fcd/fyd)·(εcu/(εcu+εyd))
→ Beam Flexural Design Calculator
7.2 Shear Design — TS 500:2000 Cl. 8
Concrete contribution (no shear reinforcement):
Vcr = 0.65·fctd·bw·d (simplified, Cl. 8.1.2)
With stirrups: Vr = Vcr + (Asw/s)·fywd·d·cot α
Maximum shear: Vr,max = 0.22·fcd·bw·d (Cl. 8.2.4)
→ Beam Shear Design Calculator
7.3 Column Design — TS 500:2000 Cl. 7.4
Short column (λ = L0/i ≤ 40): P-M interaction. See Column PMM Design Calculator.
Slender column (λ > 40): second-order moments must be added per TS 500 Cl. 7.4.
Min. steel: As ≥ 0.01·Ac; max: As ≤ 0.04·Ac (0.06 at laps).
7.4 Torsion — TS 500:2000 Cl. 8.3
Threshold: Tcr = 0.65·fctd·Acp²/pcp. Below this threshold, torsion may be neglected in combination with shear. Above threshold: closed stirrups + longitudinal reinforcement per Cl. 8.3.
8.1 Non-Seismic Detailing (DTS 4)
Standard cover, development lengths, and stirrup spacing per TS 500:2000 Cl. 9–11. No special ductile detailing required.
→ Development Length Calculator (TS 500)
8.2 YDMÇ Beam Detailing — TBDY 2018 Madde 7.3
Sarılma bölgesi (confinement region): 2h from face of column at each end — Madde 7.3.4
Hoop spacing in confinement: se ≤ min(h/4, 8dbL, 24dbw, 200 mm) — Madde 7.3.4.1
Outside confinement: s ≤ h/2; minimum dbw ≥ 8 mm
Minimum 2 bars top and bottom throughout span. Positive moment capacity at support face ≥ 50% of negative moment capacity — Madde 7.3.2.
8.3 YDMÇ Column Detailing — TBDY 2018 Madde 7.4
Sarılma bölgesi: l0 = max(Hk/6, bk, hk, 500 mm) from each column end — Madde 7.4.3.1
Hoop spacing in confinement: se ≤ min(b0/3, 6dbL, 150 mm) — Madde 7.4.4.1
b0 = confined core dimension (to centreline of outermost hoop)
Güçlü kolon–zayıf kiriş (Strong column–weak beam): ΣMra(kol) ≥ 1.2·ΣMra(kiriş) at each joint — Madde 7.4.2
8.4 SDMÇ Detailing — TBDY 2018 Madde 7.8 / 7.9
Beam confinement region: 2h from face of column.
Hoop spacing in confinement: se ≤ min(h/3, 10dbL, 200 mm) — Madde 7.8.3
Column confinement: l0 same as YDMÇ; hoop spacing: se ≤ min(b0/2, 8dbL, 200 mm) — Madde 7.9.3
8.5 Shear Wall (Perde) Boundary Elements — TBDY 2018 Madde 7.6
Uç bölgeleri (boundary elements) required when compression zone exceeds threshold. High ductility: detailed transverse reinforcement over lc ≥ max(0.15·lw, 1.5·bw).
9.1 Interstorey Drift Limits — TBDY 2018 Madde 4.9
Göreli kat ötelemesi (reduced interstorey drift): δi = R·ui/I (amplified from elastic analysis)
| Condition | Limit δi,max/hi |
|---|---|
| RC frames with brittle infill | 0.008 |
| RC frames with ductile / no infill | 0.016 |
| Seismic isolation systems | Per isolation design |
Checked under DD-3 (72-year) earthquake — Madde 4.9.1.
9.2 Diaphragm Design — TBDY 2018 Madde 4.5.6
Döşemeler (floor slabs) assumed rigid diaphragms in standard buildings. Collector elements and chord reinforcement designed for in-plane diaphragm forces. Flexible diaphragm modelling required for irregular plans or large openings.
9.3 Irregularity Checks — TBDY 2018 Madde 3.6
TBDY defines plan irregularities (A1–A3) and vertical irregularities (B1–B3). Buildings with certain irregularities must use Modal Response Spectrum Analysis (Mod Spektrum Analizi) rather than ELF — Madde 4.3.2.
- A1: Torsion irregularity — ratio of max/mean drift > 1.2 at any storey
- B1: Soft storey — storey stiffness < 70% of storey above (or < 80% of avg 3 above)
- B2: Mass irregularity — storey mass > 1.5× adjacent storey mass