Peru Steel Roof Truss Project Material List And Structural Load Analysis

Huachipa, Lima Steel Roof Truss Project - Material List & Structural Load Analysis

 

 

This project is located in Huachipa, Lima, Peru, focusing on the design and construction of steel roof truss system (excluding steel columns and wall components). The roof is equipped with solar panels, and the design strictly complies with Peruvian local building codes. The key parameters of the project are summarized as follows:

Total Building Area: 8,900 ㎡

Total Length: 109 m

Total Width: 85 m (irregular layout with multiple spans)

Span Sizes (along 85m direction, unequal spans): 13m, 17m, 25m, 28m (maximum span: 28m)

Truss Spacing (Bay Spacing): Approximately 22m

Roof Configuration: Equipped with approximately 4,400 ㎡ solar panels (photovoltaic system)

Structural Scope: Only roof truss system (trusses, bracing, tie rods, purlins), excluding steel columns and wall frames

Applicable Codes: Peruvian local building codes

 

 

The load analysis is based on the actual environmental conditions of Huachipa, Lima, and strictly follows Peruvian codes E.030 (Seismic Code), E.050 (Wind Load Code), and E.070 (Snow Load Code). All loads are calculated in accordance with the importance level of industrial buildings (importance factor U=1.0).

 

 

Huachipa, Lima is located in Seismic Zone 4 of Peru, which is a high-intensity seismic area. The specific seismic parameters are as follows:

Seismic Zone: Zone 4, Z=0.45g (peak ground acceleration)

Site Soil Type: S1 (hard soil), site coefficient S=1.0

Seismic Impact: The roof truss system requires sufficient seismic stiffness to resist horizontal seismic forces. The truss connections and bracing system must be designed conservatively to ensure structural stability under seismic action.

 

 

Lima is a coastal city, and Huachipa area is affected by coastal winds. The wind load parameters are determined as follows:

Basic Wind Pressure: 0.55–0.65 kN/㎡

Wind Effect: The solar panels on the roof increase the wind suction and wind vibration effect. The shape coefficient of the roof is appropriately amplified to account for the impact of solar panels on wind load distribution.

Wind Resistance Requirement: The roof trusses, purlins, and bracing system must be able to resist wind suction and positive wind pressure, ensuring no structural damage or excessive deformation.

 

 

Huachipa, Lima has a tropical coastal climate with no snowfall throughout the year. Therefore, the basic snow load is determined as follows:

Basic Snow Load S₀: ≈ 0 kN/㎡

Note: No additional snow load is considered in the structural design, but the roof drainage system is designed to prevent water accumulation (equivalent to partial uniform load).

 

 

The total roof load is the sum of dead load, solar panel load, and live load, which is significantly higher than that of ordinary industrial workshops. The specific calculation is as follows:

Roof Dead Load (self-weight of roof covering + purlins): ≈ 0.30 kN/㎡

Solar Panel Load (solar panels + supports): ≈ 0.18–0.22 kN/㎡

Maintenance Live Load: 0.50 kN/㎡ (in line with Peruvian industrial building standards)

Total Roof Load: ≈ 0.98–1.02 kN/㎡

Note: The deflection of the roof trusses and purlins must be controlled within L/200 (L is the span of trusses or purlins) to ensure the stability of the solar panel system.

 

The material selection is based on Peruvian local steel standards and project load requirements, focusing on durability, seismic performance, and cost-effectiveness. The detailed material list is as follows:

 

 

Steel Grade: Chinese Standard Q355B/Q235B (equivalent to A36 in ASTM standard), with good strength and ductility, suitable for high seismic areas.

Section Type:

Top Chord & Bottom Chord: H-section steel - selected according to span and load, with section size range: H300×150×6×8 to H400×200×8×10 (adjusted based on different spans: 13m/17m/25m/28m).

Web Members: Angle steel or I-section steel - section size range: L75×5 to L100×8 (for 13m/17m spans); L100×8 to L125×10 (for 25m/28m spans).

Connection Method: High-strength bolts (10.9 grade) for connection, ensuring reliable connection and seismic resistance.

Treatment: With Epoxy zinc-rich primer paint in 80μm

 

 

Steel Grade: Chinese Standard Q235B

Section Type: Round steel (φ16–φ22) or angle steel (L63×5–L80×6), used to resist horizontal forces (seismic, wind) and maintain the stability of the truss system.

Arrangement: Bracing is set at intervals of 2–3 trusses, with cross-bracing and diagonal bracing arranged alternately to form a stable lateral force-resisting system.

Treatment: With Epoxy zinc-rich primer paint in 80μm

 

 

Steel Grade: Chinese Standard Q235B

Section Type: Round steel (φ20–φ25) or steel pipe (φ89×4–φ114×4), used to transfer the horizontal tension between trusses and ensure the overall stability of the roof.

Treatment: With Epoxy zinc-rich primer paint in 80μm

 

 

Steel Grade: Chinese Standard Q235B

Section Type: C-section steel or Z-section steel (strengthened type, suitable for solar panel load), section size range: C160×60×20×2.5 to C220×70×20×3.0 (adjusted according to purlin spacing and solar panel load).

Spacing: Approximately 1.5–2.0m, ensuring that the purlins can bear the combined load of roof covering and solar panels without excessive deformation.

Treatment: Galvanization 275kg/m³

 

 

High-strength Bolts: 10.9 grade, matching the section size of trusses and bracing, with anti-corrosion treatment (hot-dip galvanizing).

Self-tapping Screws & Rivets: Corrosion-resistant stainless steel (304 grade), used for connecting purlins and roof covering, as well as solar panel supports.

Anti-corrosion Coating: Hot-dip galvanizing (zinc layer thickness ≥ 80μm) for all steel components, to adapt to the coastal humid environment of Lima and ensure service life.

 

Based on the project parameters, load analysis, and material selection, the steel consumption of the roof truss system (only) is estimated as follows, considering the high seismic requirements of Huachipa, Lima and the additional load of solar panels.

 

 

Combined with the conditions of 28m maximum span, 22m truss spacing, solar panel heavy load, and high seismic intensity in Lima, the steel consumption index of the roof truss system is determined as follows:

Roof Trusses + Bracing + Tie Rods: 18–22 kg/㎡

Roof Purlins (strengthened type): 8–11 kg/㎡

Total Steel Consumption Index: 26–33 kg/㎡ (adopting a conservative middle-upper value of 30 kg/㎡ for estimation, in line with Peruvian code requirements)

 

 

Total Steel Consumption = Total Building Area × Steel Consumption Index ÷ 1000

Calculation: 8,900 ㎡ × 30 kg/㎡ ÷ 1000 = 267 tons

 

 

Economical Optimized Design (light load, refined optimization): ≈ 230 tons

Conventional Conservative Design (complying with Peruvian codes and Lima seismic requirements): ≈ 265–270 tons

High Load / High Seismic / Strict Large-span Design: ≈ 290 tons

 

 

The above steel consumption only includes the roof truss system (trusses, bracing, tie rods, purlins), excluding steel columns, wall frames, and solar panel supports.

If steel columns are added, the total steel consumption will increase by 10–13 kg/㎡, and the total steel consumption will be approximately 340–400 tons.

The actual steel consumption may have a ±10% fluctuation after the detailed design is completed, which is mainly affected by the detailed adjustment of section sizes and connection methods.

Seismic Design: The roof truss system must be designed in accordance with Peruvian Code E.030 (Seismic Zone 4), and excessive optimization is not allowed to ensure seismic safety.

Solar Panel Load: The purlins and top chords of trusses in the solar panel area must be strengthened, and the deflection control must be stricter (within L/200) to avoid damage to the solar panel system.

Anti-corrosion Requirement: All steel components better to be hot-dip galvanized to adapt to the coastal humid environment of Lima and extend the service life of the structure.

Code Compliance: All design and construction work must comply with Peruvian local codes RNE / E.030, E.050, E.070, and relevant industrial standards.

 

 

The detailed steel consumption is divided according to the four unequal spans (13m, 17m, 25m, 28m), combined with the truss spacing of 22m and the solar panel load, and the steel consumption index is adjusted according to the span size (the larger the span, the higher the index). The specific breakdown is as follows:

Span Size	Span Length (m)	Corresponding Area (approx., ㎡)	Steel Consumption Index (kg/㎡)	Estimated Steel Consumption (tons)	Remarks
1st Span	13	2400	25	60	Smallest span, lightest load; partial solar panel coverage
2nd Span	17	2450	28	68.6	Medium span, moderate load; partial solar panel coverage
3rd Span	25	2250	32	72	Large span, heavy load; main solar panel coverage area
4th Span	28	1800	35	63	Maximum span, heaviest load; main solar panel coverage area
Total	83 (sum of spans)	8900 (total building area)	30 (average index)	263.6	Slight deviation from total estimation (±2%) due to rounding

Note: The corresponding area of each span is estimated based on the total area of 8900 ㎡ and the proportion of each span in the total width (85m), which is for reference only. The actual area and steel consumption shall be subject to the detailed design drawings.

 

Main Primary Roof Beams (H‑Sections)

- W200×750×12×6 mm

- W250×750×25×6 mm

- W350×750×25×9 mm

- W200×400×16×6 mm

 

Secondary Members

- Purlins: Z305×76×19×3.0 mm

- Horizontal/Lateral Bracing: 2"×2"×3/16" steel angle

 

 

2.1 Main Roof Structure

- Truss system:

18–22 kg/m² → **160.2 – 195.8 tons**

- H‑beam system (deep sections, 22m spacing, PV load):

24–30 kg/m² → **213.6 – 267.0 tons**

 

2.2 Bracing System

- Truss:

2.5–4.0 kg/m² → **22.3 – 35.6 tons**

- H‑beam:

3.5–5.0 kg/m² → **31.2 – 44.5 tons**

*Reason: H‑beams have less natural torsional rigidity; more bracing required.*

 

2.3 Purlins

- Both systems:

Z305 purlins, same loading and spacing

8–11 kg/m² → **71.2 – 97.9 tons**

*Nearly identical for both truss and H‑beam roofs.*

 

2.4 Total Steel Weight Comparison

- Truss roof total:

254 – 329 tons

-H‑beam roof total:

316 – 409 tons

 

 

3.1 Truss System

- Behavior: Triangulated axial forces (tension/compression only).

- Stiffness: High geometric stiffness, good for long spans and deflection control (critical for PV).

- Stability: Less dependent on bracing; inherent stability from triangular pattern.

- Seismic performance: Good energy dissipation, lightweight, lower inertia.

- Span efficiency: Extremely efficient for **25–28m spans**.

 

3.2 H‑Beam System

- Behavior: Bending + shear + axial forces.

- Stiffness: Lower flexural efficiency per kg; deeper/heavier sections needed to match truss deflection.

- Stability: Prone to lateral‑torsional buckling; requires more frequent bracing.

- Seismic performance: Higher self‑weight increases seismic demand.

- Constructability: Simpler fabrication and erection, but heavier components.

 

 

 

Similarities

- Both support the same roof loads (dead + PV + live + wind).

- Purlin size, spacing, and weight are identical.

- Both must satisfy Peruvian deflection limits (L/200 for PV).

- Both follow E.030, E.050, E.070 for Huachipa, Lima.

 

Differences

1. Force mechanism:

- Truss: Axial forces only → highly efficient.

- H‑beam: Bending governed → less material‑efficient.

2. Steel consumption:

- Main structure: H‑beam uses +25% to +40% steel.

- Bracing: H‑beam needs +30% to +40% more bracing.

- Purlins: Almost same.

3. Span performance:

- Truss: Superior for 25–28m spans.

- H‑beam: Requires heavy sections to control deflection.

4. Seismic behavior:

- Truss: Lighter, lower inertia, better performance in Zone 4.

- H‑beam: Heavier, higher seismic load.

5. Cost & construction:

- Truss: More labor, less material.

- H‑beam: Less labor, more material.

 

 

- Truss system:

More efficient, lighter steel usage, better for long spans and high seismic zones.

Total steel: 254 – 329 tons.

 

-H‑beam system:

Easier construction but significantly heavier.

Total steel: 316 – 409 tons.