Project Overview
Project P-2023-061 was the structural engineering commission for a pre-engineered steel building (PEB) superstore in the UAE. Hypermarket buildings require large unobstructed floor areas to accommodate retail display, customer circulation, and back-of-house logistics — clear spans of 30–50 metres are typical, achieved most economically through the tapered rigid frame configurations characteristic of pre-engineered building systems.
The UAE construction industry predominantly uses European standards (Eurocode) or AISC-based American standards, reflecting the international engineering workforce and multinational construction companies active in the region. This project was designed to the Eurocode suite: EN 1990 (structural basis of design), EN 1991 (actions on structures), EN 1993 (design of steel structures), and EN 1997 (geotechnical design).
Pre-Engineered Building Systems
Pre-engineered buildings (PEB) are structural steel building systems optimised for efficient material use through variable-depth (tapered) members. Unlike conventional steel construction using hot-rolled wide-flange sections of uniform depth, PEB primary frames use built-up welded sections with web depth and flange plate sizes varied along the member length in proportion to the bending moment diagram. This allows material to be concentrated where bending demand is highest (typically at the eaves of a portal frame) and reduced where demand is lower (at the ridge and in the column mid-height region).
The result is a very efficient structure by weight — PEB systems typically achieve 20–35% lower steel tonnage than equivalent conventional steel construction. For large commercial buildings like hypermarkets, this weight saving translates directly to construction cost savings and shorter erection schedules.
Eurocode Design Framework
EN 1990 — Basis of Design
EN 1990 establishes the reliability framework for Eurocode design: performance requirements, design situations (persistent, transient, accidental), limit state definitions (ultimate limit states and serviceability limit states), and partial factor methodology. The partial factors for actions (γG for permanent loads, γQ for variable loads) and for material resistance (γM0, γM1, γM2 for steel) define the safety format that all Eurocode design checks use. This is fundamentally different from the AISC Load and Resistance Factor Design (LRFD) format used in American standards, though both implement a reliability-based design philosophy.
EN 1991 — Actions on Structures
EN 1991-1-3 covers snow loads; EN 1991-1-4 covers wind actions. For the UAE project, wind governs most structural checks — the UAE has no meaningful snow load, but sandstorm-driven wind events and summer Gulf shamal winds produce significant wind pressures on large-area roof structures. The reference wind velocity for the UAE site was taken from the UAE National Annex to EN 1991-1-4, which provides country-specific wind maps and terrain roughness categories.
EN 1991-1-1 imposed loads for commercial superstore occupancy classified this structure as retail category, with the appropriate characteristic floor load per EN 1991 Table 6.2 applied to the structural design of mezzanine areas and loading dock platforms within the building.
EN 1993 — Steel Design
EN 1993-1-1 is the primary steel design standard, covering cross-section classification, member resistance checks, and stability (buckling) checks. For PEB tapered members, the general method of EN 1993-1-1 Section 6.3.4 for irregular members governs lateral torsional buckling checks — a more complex calculation than for prismatic sections, requiring numerical interpolation of buckling curves along the member length.
EN 1993-1-8 covers connection design. Bolted and welded connections in Eurocode are designed using the component method, which decomposes each connection into basic components (bolt rows in tension, compression zone, weld throat, etc.) with defined resistances, then assembles the components to determine the overall connection resistance and stiffness.
Large-Span Roof Design
The hypermarket main roof spans approximately 40 metres clear between column lines, achieved through tapered portal frames at 6-metre spacing. The portal frame eave connections — where beam meets column — are the most heavily loaded joints in the structure. These moment connections were designed as bolted extended end-plate connections per EN 1993-1-8, providing the required moment resistance and rotational stiffness while being practical to fabricate and erect.
Roof deflection under dead load plus full imposed load was checked against EN 1993 serviceability limits: L/250 for maximum deflection, and L/350 for post-installation deflection after cladding is installed. The latter limit is critical because excessive sag after cladding can cause ponding — water accumulation on flat or low-slope roofs that increases the load and causes further deflection in a progressive manner. The roof profile was specified with a minimum 1:50 slope to allow free drainage and avoid ponding risk.
Foundation in UAE Ground Conditions
The UAE coastal areas where many commercial developments are located present sandy soils with variable cementation. Spread footings on dense sand were used for the column bases, with footing sizes determined by EN 1997-1 ultimate limit state (ULS) and serviceability limit state (SLS) bearing capacity checks. The geotechnical design confirmed adequate bearing capacity at the footing depth specified, with settlement estimates within acceptable limits for a rigid steel structure on spread footings.
Eurocode design in the UAE requires the relevant UAE National Annexes. Not all EN partial factors and design values apply without modification — country-specific parameters must be applied for an authority-compliant design.