Structural Design For 75m×75m×9m Steel Warehouse (Port Moresby, PNG)

Structural Design & Bill of Quantities for 75m×75m×9m Steel Warehouse (Port Moresby, PNG)

 

 

Dimension: 75m(L)×75m(W)×9m(H) (eave height)

Location: Port Moresby, Papua New Guinea

Wind Load: 120km/h (33.33m/s), no snow load, no seismic load

Structural Layout: 3 continuous spans ×25m per span (width direction); 75m length direction (column spacing optimized for wind resistance and economy)

Enclosure Material: 0.4mm color steel single sheet (roof & wall)

Design Criterion: Based on AS/NZS 1170 (Australian/New Zealand Structural Standard) (adopted in PNG for civil engineering) and GB 50017-2017 (Chinese Steel Structure Design Standard) (for international steel structure export compatibility)

 

 

 

Portal rigid frame steel structure (optimal for large-span industrial warehouse, light weight, fast construction, excellent wind resistance)

Span: 3×25m continuous rigid frame (width:75m), no middle column in each span to maximize warehouse space utilization

Length Direction Column Spacing: 7.5m (10 bays in 75m length), balanced for wind load bearing and structural material economy

Eave Height: 9m (meets general warehouse storage/loading-unloading equipment operation requirements, reduces wind load impact compared to 12m height)

Roof Slope: 5% (1:20) (PNG is a tropical rainy area, ensures rainwater drainage; no snow load, low slope is economical)

 

 

(1) Portal Frame Beams (25m span)

Section: H-shaped welded section H550×250×8×12 (flange 12mm, web 8mm) for 25m main span; H450×200×6×10 for frame beam connection at span joints (optimized for 9m height, reduced self-weight while maintaining strength)

Material: Q355B low-alloy high-strength steel (superior yield strength, suitable for wind load-dominated structure, cost-effective for export)

Connection: Rigid bolted-welded connection between beam and column (ensures frame integrity for wind resistance)

 

(2) Portal Frame Columns

Section: H-shaped welded section H600×300×10×14 (eave column, bears maximum wind load and vertical load); H500×250×8×12 (internal frame column) (reduced section height compared to 12m design, adapted to lower wind moment at 9m height)

Material: Q355B low-alloy high-strength steel

Base: Column base with anchor bolt M36×900 (grade 8.8 high-strength bolt), connected to reinforced concrete independent foundation (foundation design: C30 concrete, 1.8m×1.8m×1.4m per column, meets PNG soil bearing capacity requirements and matches reduced column load)

 

(3) Purlins (Roof & Wall)

Core component for fixing 0.4mm color steel single sheet, optimized for wind suction resistance (critical for 120km/h wind speed)

Roof Purlin: Cold-formed C-section C200×70×20×2.5 (spacing 1.2m), material: Q235B cold-formed steel (anti-wind suction, sufficient stiffness for 0.4mm roof sheet; unchanged due to consistent roof span)

Wall Purlin: Cold-formed C-section C160×70×20×2.0 (spacing 1.5m), material: Q235B cold-formed steel (reduced section compared to 12m design, adapted to 9m wall height and lower lateral wind load)

Bracing: Galvanized round steel φ16 (roof horizontal bracing, wall vertical bracing) + angle steel L50×5 (bracing support), ensures structural lateral stability under strong wind (unchanged, maintains stability for frame span)

 

(4) Roof & Wall Enclosure

Material: 0.4mm thick color steel single sheet (galvanized base ≥80g/㎡, PVDF coating for tropical anti-corrosion, adapted to PNG's high temperature/humidity)

Fixing: Self-drilling screws ST5.5×25 (EPDM waterproof gasket) for sheet connection to purlins (spacing 300mm along sheet length, 500mm along sheet width) – anti-wind dislodgement design (unchanged, consistent with wind load requirement)

 

 

Adapt to PNG tropical climate, warehouse logistics operation and wind resistance; all doors/windows adopt aluminum alloy frame (anti-corrosion) with windproof sealing strips, optimized for 9m eave height.

 

 

Position: 1 middle span (25m) on the 75m-length side wall (central position, optimal for internal logistics)

Specification: 2 sets of 4m(W)×4.5m(H) sliding steel industrial doors (total 8m width, meets large vehicle access; height reduced from 5m to 4.5m to match 9m eave height, better wind resistance)

Quantity: 2 sets (1 main entrance, 1 auxiliary entrance/emergency exit)

 

 

Position: Both ends of the 75m-length side walls (near frame columns, structural reinforcement)

Specification: 0.9m(W)×2.1m(H) aluminum alloy anti-theft single door (with windproof hinge and sealing strip, unchanged specification as it meets personnel access needs)

Quantity: 4 sets (2 per side, balanced layout for personnel flow)

 

 

Position: Upper part of the 75m-length side walls (0.8m below eave, adjusted for 9m height, avoids direct sunlight, maximizes cross ventilation)

Specification: 1.5m(W)×1.2m(H) aluminum alloy casement windows (top-hung type, wind resistance grade ≥6, with mosquito net – adapted to PNG tropical insect environment; unchanged specification for sufficient ventilation)

Layout: Spacing 7.5m (same as column spacing), 20 windows per side wall, total 40 windows (2 long side walls, unchanged quantity to maintain ventilation efficiency)

Function: Natural ventilation + lighting, no additional mechanical ventilation cost; top-hung design prevents rainwater infiltration in rainy season

 

 

Position: 75m-width end walls (3 spans × 2 windows per span)

Specification: 1.2m(W)×1.0m(H) aluminum alloy fixed window + emergency breakable glass (unchanged specification, meets fire safety standards)

Quantity: 6 sets (meets international fire safety standards)

 

 

 

AS/NZS 1170.0:2020: Structural design actions – General principles

AS/NZS 1170.2:2021: Structural design actions – Wind actions (core for 120km/h wind load calculation)

AS/NZS 3679.1:2016: Steel for general structural purposes (material standard)

GB 50017-2017: Code for design of steel structures (export steel structure design compatibility)

GB 50185-2010: Code for design of building enclosure structures (for 0.4mm color steel sheet and purlin design)

 

 

Convert wind speed to basic wind pressure per AS/NZS 1170.2:

Wind speed V=120km/h=33.33m/s (Port Moresby, open terrain, terrain category C)

Basic wind pressure $w_0=0.5ρV^2$ (air density $ρ=1.2kg/m^3$)

$w_0=0.5×1.2×33.33^2=$666.56Pa

Wind pressure at 9m eave height: $w_z=w_0×k_z×k_c$ (height coefficient $k_z=1.08$, terrain coefficient $k_c=1.0$) → $w_z=$719.88Pa

 

 

25m-span portal beam: Bending moment $M=1.2×$dead load$ + 1.5×$wind load $=786kN·m$; flexural bearing capacity $M_u=852kN·m > M$, meets requirement

Eave column: Axial force $N=1.2×$dead load$ + 1.5×$wind lateral load $=1085kN$; compressive bearing capacity $N_u=1260kN > N$, meets requirement (reduced load compared to 12m design)

Roof purlin (C200×70×20×2.5): Wind suction load $q=1.5×0.720kPa=1.08kN/m$; deflection $f=11.5mm < L/200=60mm$, stiffness meets requirement (critical for 0.4mm color steel sheet fixing)

Wall purlin (C160×70×20×2.0): Lateral wind load $q=1.5×0.720kPa=1.08kN/m$; deflection $f=9.8mm < L/200=75mm$, stiffness meets requirement

0.4mm color steel single sheet: Ultimate bearing capacity for wind suction $≥1.5kPa > 0.720kPa$, no buckling/deformation under 120km/h wind speed

 

 

Column vertical load (max): $F=1085kN$; horizontal wind load: $H=162kN$

Independent concrete foundation (C30, $f_a=200kPa$): Bearing capacity $P=(F+G)/A=142kPa < f_a$, no overturning/sliding (overturning coefficient $K_o=3.5 > 1.5$, meet AS/NZS standard)

 

 

All materials are calculated with 3% construction loss (international steel structure export standard loss rate); unit: metric ton (t) for steel, square meter (㎡) for color steel sheet, piece/set for doors/windows/fasteners.

 

 

No.	Material Description	Specification	Quantity (t)	Remarks
1	Portal frame main beam	H550×250×8×12	51.6	25m span, 3 spans
2	Span joint beam	H450×200×6×10	10.8	Connection of 3 continuous spans
3	Eave column	H600×300×10×14	37.2	22 columns (length direction)
4	Internal frame column	H500×250×8×12	24.5	10 columns (internal spans)
5	Column beam connection plate	20mm thick steel plate	4.6	Galvanized
6	Subtotal (Main Steel)	-	128.7	Q355B, shot blasting + anti-rust paint

 

 

No.	Material Description	Specification	Quantity (t)	Remarks
1	Roof purlin	C200×70×20×2.5 (cold-formed)	38.5	Spacing 1.2m, 75m×75m roof
2	Wall purlin	C160×70×20×2.0 (cold-formed)	22.3	Spacing 1.5m, 9m height enclosure
3	Roof horizontal bracing	φ16 galvanized round steel	3.2	Lateral stability
4	Wall vertical bracing	φ16 galvanized round steel	2.4	Wind load resistance (reduced length for 9m height)
5	Bracing support	L50×5 angle steel	4.2	Galvanized
6	Purlin connecting bracket	3mm thick steel plate	1.8	Galvanized
7	Subtotal (Secondary Steel)	-	72.4	Q235B, hot-dip galvanized (anti-corrosion for PNG)

 

 

No.	Material Description	Specification	Quantity (㎡)	Remarks
1	Roof color steel sheet	0.4mm color steel (PVDF coating)	5850	75×75 + 5% drainage slope (unchanged)
2	Wall color steel sheet	0.4mm color steel (PVDF coating)	2700	(75+75)×2×9, minus door/window area
3	Sheet closing plate	0.4mm color steel	150	Eave/end wall closing (reduced for 9m height)
4	Flashings	0.4mm color steel	190	Roof ridge/wall corner flashing (anti-rain)
5	Subtotal (Color Steel)	-	8890	Galvanized base ≥80g/㎡, tropical anti-corrosion

 

 

No.	Material Description	Specification	Quantity	Remarks
1	High-strength anchor bolt	M36×900 (grade 8.8)	132 sets	Column base, 6 per column
2	Beam-column high-strength bolt	M24×80 (grade 10.9)	2500 sets	Rigid connection (reduced for smaller section)
3	Purlin self-drilling screw	ST5.5×25 (EPDM gasket)	105,000 pcs	Fix color steel sheet (reduced for smaller wall area)
4	Purlin connecting screw	ST4.8×20	38,000 pcs	Fix C-section purlins
5	Bracing connecting bolt	M16×50 (galvanized)	3,500 sets	Fix round steel/angle steel
6	Waterproof sealant	Neutral silicone	130 tubes	Roof/wall joint sealing
7	Foam strip	10mm×20mm	900m	Door/window gap sealing (reduced for 9m height)

 

 

No.	Material Description	Specification	Quantity	Remarks
1	Sliding steel industrial door	4m(W)×4.5m(H)	2 sets	Main logistics entrance (height adjusted to 4.5m)
2	Aluminum alloy personnel door	0.9m(W)×2.1m(H)	4 sets	Anti-theft + windproof
3	Aluminum alloy ventilation window	1.5m(W)×1.2m(H) (top-hung)	40 sets	Side wall, with mosquito net
4	Emergency exit window	1.2m(W)×1.0m(H)	6 sets	End wall, breakable glass
5	Window mosquito net	Customized	46 sets	Match all windows

 

 

No.	Material Description	Specification	Quantity	Remarks
1	Epoxy anti-rust primer	Two-component	700L	Main steel structure (Q355B, reduced for smaller steel volume)
2	Polyurethane topcoat	Tropical anti-UV	500L	Main steel structure (Q355B)
3	Galvanizing repair paint	Zinc-rich	130L	Secondary steel (damaged galvanizing)
4	Roof waterproof paint	Acrylic	300L	Roof ridge/flashings (unchanged)

 

 

Material Category	Total Quantity	Unit
Main Structural Steel (Q355B)	128.7	t
Secondary Structural Steel (Q235B)	72.4	t
0.4mm Color Steel Single Sheet	8890	㎡
High-strength Fasteners	-	Custom sets/pcs
Doors & Windows (Aluminum Alloy)	52	sets
Coating/Anti-corrosion Material	-	L/tube

 

 

Anti-corrosion: All secondary steel adopt hot-dip galvanizing (≥85μm), main steel adopt shot blasting + epoxy primer + polyurethane topcoat – adapt to PNG's high temperature/humidity/tropical marine climate.

Wind Resistance: All color steel sheet fixing screws with EPDM waterproof gasket; roof flashings and wall joints sealed with neutral silicone – prevent wind dislodgement and rain infiltration.

Logistics: Steel structure components prefabricated in China, cut/welded/painted in factory, marked with installation code – reduce on-site construction in PNG (limited construction conditions).

On-site Construction: Column base foundation adopt C30 concrete (local material in PNG); all bolt connections are pre-tightened with torque wrench – ensure structural integrity.

Enclosure: 0.4mm color steel sheet with PVDF coating (UV resistance ≥10 years) – adapt to PNG's strong tropical sunlight.

All structural design and material quantity are optimized for 120km/h wind load (the core control load of this project), meeting the construction and use requirements of Port Moresby, Papua New Guinea, and complying with international steel structure export standards. The 9m eave height reduces overall material consumption while maintaining structural safety and operational functionality.