{"id":11435,"date":"2026-08-22T04:39:35","date_gmt":"2026-08-22T04:39:35","guid":{"rendered":"https:\/\/geelyracks.com\/"},"modified":"2026-08-22T04:45:03","modified_gmt":"2026-08-22T04:45:03","slug":"racking-design-code","status":"publish","type":"post","link":"https:\/\/geelyracks.com\/eo\/racking-design-code\/","title":{"rendered":"GB\/T 39681-2020: Ultimate Racking Design Code Guide"},"content":{"rendered":"

GB\/T 39681-2020: The Definitive Racking Design<\/a> Code for Steel Static Storage Systems<\/span><\/h2>\n

A Comprehensive Technical Guide to Racking Design Standards, Load Combinations, Material Selection, Structural Analysis, and Performance Testing for Modern Warehouse Operations<\/span><\/strong><\/p>\n

Executive Summary<\/span><\/h2>\n

The\u00a0<\/span>GB\/T 39681-2020 “Racking design code for steel static storage systems”<\/span><\/strong>\u00a0represents the most authoritative and comprehensive\u00a0<\/span>racking design<\/span><\/strong><\/a>\u00a0<\/a>standard for warehouse storage systems in the People’s Republic of China<\/span>. Published on December 14, 2020, and formally implemented on July 1, 2021, this national\u00a0<\/span>racking design<\/span><\/strong><\/a>\u00a0<\/a>standard establishes the foundational requirements for material selection, load calculations, structural design methodologies, and performance testing for steel storage racking systems<\/span>.<\/span><\/p>\n

Developed under the leadership of the China Machinery Industry Federation and administered by the National Technical Committee for Logistics Warehousing Equipment (SAC\/TC 499), GB\/T 39681-2020 was drafted by seven leading organizations including Shanghai Jingxing Storage Equipment Engineering Co., Ltd., Beijing Materials Handling Research Institute Co., Ltd., Beijing Jingbangda Trading Co., Ltd., Donghua University, and other prominent industry institutions<\/span>. The\u00a0<\/span>racking design<\/span><\/strong><\/a>\u00a0<\/a>standard applies to steel static storage systems fabricated from cold-formed steel or hot-rolled steel components, addressing the critical need for standardized, safe, and reliable\u00a0<\/span>racking design<\/span><\/strong>\u00a0in modern logistics operations<\/span>.<\/span><\/p>\n

The introduction of this\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard addressed significant gaps in previous industry guidelines. Prior to its implementation, the sector relied on outdated technical specifications that failed to account for modern lightweight high-strength steel applications and plug-in installation techniques<\/span>. The new\u00a0<\/span>racking design<\/span><\/strong>\u00a0code has been instrumental in standardizing\u00a0<\/span>racking design<\/span><\/strong>\u00a0practices across the industry, eliminating inconsistent approaches, enhancing safety through rigorous load combination requirements, and promoting quality by establishing clear material and testing specifications<\/span>.<\/span><\/p>\n

This comprehensive guide examines every aspect of GB\/T 39681-2020, providing warehouse operators, design engineers, and logistics professionals with the technical knowledge required to design, specify, and verify steel storage racking systems that meet China’s highest safety and performance standards.<\/span><\/p>\n

\n

H1: Understanding the Scope and Purpose of GB\/T 39681-2020<\/span><\/h2>\n

H2: What the Racking Design Standard Covers<\/span><\/h3>\n

GB\/T 39681-2020 establishes the complete framework for designing steel static storage systems used in automated and conventional warehouses. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard systematically addresses the following critical areas<\/span>:<\/span><\/p>\n

    \n
  • \n

    Terminology and definitions<\/span><\/strong>\u00a0specific to\u00a0<\/span>racking design<\/span><\/strong>\u00a0systems<\/span><\/p>\n<\/li>\n

  • \n

    Material specifications<\/span><\/strong>\u00a0for steel components and connectors<\/span><\/p>\n<\/li>\n

  • \n

    Load classification and combination<\/span><\/strong>\u00a0methodologies<\/span><\/p>\n<\/li>\n

  • \n

    Racking design principles<\/span><\/strong>\u00a0for columns, beams, and base plates<\/span><\/p>\n<\/li>\n

  • \n

    Test methods<\/span><\/strong>\u00a0for determining key\u00a0<\/span>racking design<\/span><\/strong>\u00a0parameters<\/span><\/p>\n<\/li>\n

  • \n

    Overall unit testing<\/span><\/strong>\u00a0for combined\u00a0<\/span>racking design<\/span><\/strong>\u00a0assemblies<\/span><\/p>\n<\/li>\n<\/ul>\n

    H2: Why This Racking Design Standard Matters<\/span><\/h3>\n

    The introduction of GB\/T 39681-2020 addressed significant gaps in previous industry standards. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0code has transformed the industry by providing a unified framework that<\/span>:<\/span><\/p>\n

      \n
    • \n

      Standardizes racking design practices<\/span><\/strong>\u00a0across the industry, eliminating inconsistent approaches<\/span><\/p>\n<\/li>\n

    • \n

      Enhances safety<\/span><\/strong>\u00a0through rigorous load combination requirements<\/span><\/p>\n<\/li>\n

    • \n

      Promotes quality<\/span><\/strong>\u00a0by establishing clear material and testing specifications<\/span><\/p>\n<\/li>\n

    • \n

      Facilitates international trade<\/span><\/strong>\u00a0by providing an English-language version (GB\/T 39681-2020E)<\/span><\/p>\n<\/li>\n<\/ul>\n

      As industry experts have noted, the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard “will further regulate or improve the terminology of three-dimensional warehouse racks, guide enterprises to standardized\u00a0<\/span>racking design<\/span><\/strong>\u00a0and large-scale production, and also provide unified delivery acceptance specifications for manufacturers, distributors, consumers, quality inspection, industry and commerce and other related institutions”<\/span>.<\/span><\/p>\n

      H2: The Racking Design Standard’s Historical Context<\/span><\/h3>\n

      The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard was developed in response to the rapid evolution of warehouse storage technology. The previous industry standard, CECS23:90, had become technologically obsolete and could not adequately address the complexities of modern\u00a0<\/span>racking design<\/span><\/strong>. Key drivers for the new\u00a0<\/span>racking design<\/span><\/strong>\u00a0code included:<\/span><\/p>\n

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      • \n

        The emergence of lightweight high-strength steel<\/span><\/strong>\u00a0materials in\u00a0<\/span>racking design<\/span><\/strong><\/p>\n<\/li>\n

      • \n

        The widespread adoption of plug-in connection systems<\/span><\/strong>\u00a0in\u00a0<\/span>racking design<\/span><\/strong><\/p>\n<\/li>\n

      • \n

        The growth of automated storage and retrieval systems<\/span><\/strong>\u00a0requiring specialized\u00a0<\/span>racking design<\/span><\/strong>\u00a0considerations<\/span><\/p>\n<\/li>\n

      • \n

        The need for international harmonization<\/span><\/strong>\u00a0of\u00a0<\/span>racking design<\/span><\/strong>\u00a0practices<\/span><\/p>\n<\/li>\n<\/ul>\n

        The development of this\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard was supported by the Shanghai Innovation Action Plan Project (Standard Special: 15DZ0500400) and the Shanghai Natural Science Foundation Project (15ZR1400600), reflecting the significant investment in improving\u00a0<\/span>racking design<\/span><\/strong>\u00a0practices<\/span>.<\/span><\/p>\n

        \"Modern
        Modern Automated Warehouse With Steel Storage Racking Design Systems Following Standards For Safety And Efficiency<\/figcaption><\/figure>\n
        \n

        H1: Material Selection Under GB\/T 39681-2020<\/span><\/h2>\n

        H2: Steel Specifications for Different Operating Environments<\/span><\/h3>\n

        The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard provides explicit material requirements based on the operating temperature of the storage facility.<\/span><\/p>\n

        H3: Ambient Temperature Warehouses<\/span><\/h4>\n

        For standard warehouse environments, the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard recommends steels conforming to<\/span>:<\/span><\/p>\n

          \n
        • \n

          Q235<\/span><\/strong>\u00a0(Grade 235) carbon structural steel per GB\/T 700<\/span><\/p>\n<\/li>\n

        • \n

          Q355<\/span><\/strong>\u00a0(Grade 355) and\u00a0<\/span>Q460<\/span><\/strong>\u00a0(Grade 460) high-strength low-alloy structural steels per GB\/T 1591<\/span><\/p>\n<\/li>\n<\/ul>\n

          The inclusion of Q460 steel in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard represents a significant advancement, as it allows for higher load capacity and more efficient structural design<\/span>. These materials offer the optimal balance of strength, ductility, and cost-effectiveness for typical storage applications. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard also permits the use of other steels with superior mechanical properties, recognizing ongoing material innovations in the industry<\/span>.<\/span><\/p>\n

          H3: Cold Storage and Freezer Environments<\/span><\/h4>\n

          For warehouses operating at or below\u00a0<\/span>-20\u00b0C<\/span><\/strong>, the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard imposes more stringent material requirements<\/span>. Primary load-bearing components must use<\/span>:<\/span><\/p>\n

            \n
          • \n

            Q355C\/D<\/span><\/strong>\u00a0or\u00a0<\/span>Q235C\/D<\/span><\/strong>\u00a0grade steels from GB\/T 1591 and GB\/T 700 respectively<\/span><\/p>\n<\/li>\n

          • \n

            Alternative steels such as Q460 must satisfy\u00a0<\/span>Charpy V-notch impact test<\/span><\/strong>\u00a0requirements at the relevant service temperature<\/span><\/p>\n<\/li>\n<\/ul>\n

            This cold-temperature provision is critical for\u00a0<\/span>racking design<\/span><\/strong>\u00a0because steel can undergo ductile-to-brittle transition at low temperatures. Without proper material selection, racking systems in cold storage facilities could experience brittle fracture under load, potentially leading to catastrophic failure. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard’s attention to this detail demonstrates its comprehensive approach to safety.<\/span><\/p>\n

            H3: Galvanized Steel Sheet<\/span><\/h4>\n

            When galvanized steel is specified in\u00a0<\/span>racking design<\/span><\/strong>, the standard references GB\/T 2518 “Continuously hot-dip zinc and zinc alloy coated steel sheet and strip.” The performance requirements for galvanized materials must still satisfy the provisions regarding base steel properties<\/span>.<\/span><\/p>\n

            H2: Connector Requirements in Racking Design<\/span><\/h3>\n

            Connectors\u2014including\u00a0<\/span>welds and bolts<\/span><\/strong>\u2014must have strength design values conforming to GB 50018 “Technical Code of Cold-formed Thin-wall Steel Structures”<\/span>. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard specifically recommends\u00a0<\/span>Grade 8.8 bolts or higher<\/span><\/strong>, ensuring that connection hardware does not become the weak link in the structural system<\/span>.<\/span><\/p>\n

            This requirement reflects the understanding that in cold-formed steel racking systems, connections often govern structural performance. The semi-rigid nature of bolted connections in\u00a0<\/span>racking design<\/span><\/strong>\u00a0requires careful design consideration, as these connections influence column effective lengths and overall frame stability.<\/span><\/p>\n

            \n

            H1: Load Classification and Combination Requirements in Racking Design<\/span><\/h2>\n

            H2: The Complete Load Inventory<\/span><\/h3>\n

            GB\/T 39681-2020 establishes a comprehensive framework for identifying and quantifying all loads that may act on a racking structure<\/span>.<\/span><\/p>\n

            H3: Dead Load (P<\/span><sub><\/span>DL<\/span><\/sub><\/span>)<\/span><\/h4>\n

            Dead load comprises the\u00a0<\/span>self-weight of the racking system<\/span><\/strong>\u00a0itself<\/span>. For\u00a0<\/span>rack-clad buildings<\/span><\/strong>\u00a0(where the racking structure supports the building envelope), dead load must also include roof and wall structures<\/span>. Additionally, all permanent fixtures attached to the racks\u2014including fire sprinkler systems, heating ventilation and air conditioning equipment, and other fixed auxiliary devices\u2014must be included in dead load calculations.<\/span><\/p>\n

            H3: Live Load (P<\/span><sub><\/span>PL<\/span><\/sub><\/span>)<\/span><\/h4>\n

            Live load generally refers to the weight of\u00a0<\/span>stored goods and pallets or carriers<\/span><\/strong>\u00a0placed on the racking structure<\/span>. This represents the primary operational load and typically dominates the design of storage racking systems. Accurate determination of live load is fundamental to proper\u00a0<\/span>racking design<\/span><\/strong>.<\/span><\/p>\n

            H3: Vertical Impact Load (P<\/span><sub><\/span>LL<\/span><\/sub><\/span>)<\/span><\/h4>\n

            One of the most critical load types addressed by the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard is\u00a0<\/span>vertical impact load<\/span><\/strong>\u2014the additional force generated when goods are deposited onto beams. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard specifies<\/span>:<\/span><\/p>\n

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            • \n

              Automated equipment<\/span><\/strong>\u00a0(mechanical placement):\u00a0<\/span>50% of the maximum unit load<\/span><\/strong><\/p>\n<\/li>\n

            • \n

              Manual placement<\/span><\/strong>\u00a0(non-automated):\u00a0<\/span>100% of the maximum unit load<\/span><\/strong><\/p>\n<\/li>\n<\/ul>\n

              As the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard’s explanatory notes clarify, international standards like EN 15512:2020(E) and ANSI MH 16.1:2012 specify 25% of the combined goods and carrier weight<\/span>. China’s 50% requirement in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard provides an additional safety margin and aligns with domestic design practices<\/span>. Importantly, vertical impact loads are\u00a0<\/span>dynamic loads of short duration<\/span><\/strong>\u00a0and are only applied to local components (beams, brackets, and connections), not for overall structural\u00a0<\/span>racking design<\/span><\/strong>.<\/span><\/p>\n

              H3: Horizontal Load (P<\/span><sub><\/span>HL<\/span><\/sub><\/span>)<\/span><\/h4>\n

              Horizontal loads arise from three primary sources in\u00a0<\/span>racking design<\/span><\/strong>:<\/span><\/p>\n

                \n
              1. \n

                Initial imperfections<\/span><\/strong>\u00a0in structural members (initial curvature)<\/span><\/p>\n<\/li>\n

              2. \n

                Installation deviations<\/span><\/strong>\u00a0and load eccentricities<\/span><\/p>\n<\/li>\n

              3. \n

                Normal operation<\/span><\/strong>\u00a0of handling equipment<\/span><\/p>\n<\/li>\n<\/ol>\n

                For imperfections and eccentricities, the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard specifies a horizontal load equal to\u00a0<\/span>0.4% of the sum of dead load and maximum live load<\/span><\/strong>\u00a0transmitted to each beam-to-column connection, applied in both longitudinal and transverse directions<\/span>.<\/span><\/p>\n

                For racks with material handling equipment, horizontal loads must be determined based on\u00a0<\/span>manufacturer-provided data<\/span><\/strong>. When such data is unavailable during the\u00a0<\/span>racking design<\/span><\/strong>\u00a0phase, the standard permits a horizontal load of 0.25kN as a conservative estimate<\/span>.<\/span><\/p>\n

                H3: Seismic Action (P<\/span><sub><\/span>EL<\/span><\/sub><\/span>)<\/span><\/h4>\n

                Seismic design requirements in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard reference\u00a0<\/span>GB 50011 “Code for Seismic Design of Buildings”<\/span><\/strong>. For racks not exceeding 40 meters in height with relatively uniform mass and stiffness distribution, the\u00a0<\/span>base shear method<\/span><\/strong>\u00a0may be used. More complex structures require the\u00a0<\/span>mode-superposition response spectrum method<\/span><\/strong>.<\/span><\/p>\n

                A particularly important provision in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard addresses seismic capacity: for member section seismic verification, the\u00a0<\/span>seismic bearing capacity strength design value<\/span><\/strong>\u00a0is taken as R\/0.75, while the\u00a0<\/span>stability design value<\/span><\/strong>\u00a0is taken as R\/0.8. This effectively reduces allowable stresses during seismic events, providing an additional safety factor in\u00a0<\/span>racking design<\/span><\/strong>.<\/span><\/p>\n

                H3: Wind Load (P<\/span><sub><\/span>WL<\/span><\/sub><\/span>) and Snow Load (P<\/span><sub><\/span>SL<\/span><\/sub><\/span>)<\/span><\/h4>\n

                For\u00a0<\/span>rack-clad buildings<\/span><\/strong>, wind load verification must comply with\u00a0<\/span>GB 50009 “Load Code for the Design of Building Structures”<\/span><\/strong>. Similarly, snow loads and roof live loads for rack-clad structures must follow GB 50009 requirements<\/span>. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard recommends using a 100-year return period for snow pressure in rack-clad structures, reflecting the sensitivity of lightweight roof systems to snow loading<\/span>.<\/span><\/p>\n

                H2: Load Combinations for Ultimate Limit State Design in Racking Design<\/span><\/h3>\n

                The\u00a0<\/span>racking design<\/span><\/strong> standard specifies eight load combination equations for various design scenarios, each with distinct load factors:<\/span><\/p>\n

                \n
                \n
                <\/div>\n<\/div>\n\n\n\n\n\n\n\n\n\n\n\n\n
                Combination<\/span><\/th>\nPurpose<\/span><\/th>\nFormula<\/span><\/th>\n<\/tr>\n<\/thead>\n
                (1)<\/span><\/td>\nStatic ultimate capacity<\/span><\/td>\n1.35P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>PL<\/span><\/sub><\/span><\/td>\n<\/tr>\n
                (2)<\/span><\/td>\nImpact on local components<\/span><\/td>\n1.2P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>HL<\/span><\/sub><\/span><\/td>\n<\/tr>\n
                (3)<\/span><\/td>\nLive + horizontal loads<\/span><\/td>\n1.2P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>HL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cW<\/span><\/sub><\/span>P<\/span><sub><\/span>WL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cR<\/span><\/sub><\/span>(P<\/span><sub><\/span>RL<\/span><\/sub><\/span>\u00a0or P<\/span><sub><\/span>SL<\/span><\/sub><\/span>)<\/span><\/td>\n<\/tr>\n
                (4)<\/span><\/td>\nWind load governing<\/span><\/td>\n1.2P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cP<\/span><\/sub><\/span>P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cP<\/span><\/sub><\/span>P<\/span><sub><\/span>HL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>WL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cR<\/span><\/sub><\/span>(P<\/span><sub><\/span>RL<\/span><\/sub><\/span>\u00a0or P<\/span><sub><\/span>SL<\/span><\/sub><\/span>)<\/span><\/td>\n<\/tr>\n
                (5)<\/span><\/td>\nSnow\/roof live governing<\/span><\/td>\n1.2P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cP<\/span><\/sub><\/span>P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cP<\/span><\/sub><\/span>P<\/span><sub><\/span>HL<\/span><\/sub><\/span>\u00a0+ 1.4\u03a8<\/span><sub><\/span>cW<\/span><\/sub><\/span>P<\/span><sub><\/span>WL<\/span><\/sub><\/span>\u00a0+ 1.4(P<\/span><sub><\/span>RL<\/span><\/sub><\/span>\u00a0or P<\/span><sub><\/span>SL<\/span><\/sub><\/span>)<\/span><\/td>\n<\/tr>\n
                (6)<\/span><\/td>\nSeismic<\/span><\/td>\n1.2P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.2P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.3P<\/span><sub><\/span>EL<\/span><\/sub><\/span><\/td>\n<\/tr>\n
                (7)<\/span><\/td>\nAnchorage (wind)<\/span><\/td>\n0.9P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 1.4P<\/span><sub><\/span>WL<\/span><\/sub><\/span><\/td>\n<\/tr>\n
                (8)<\/span><\/td>\nAnchorage (seismic)<\/span><\/td>\n0.9P<\/span><sub><\/span>DL<\/span><\/sub><\/span>\u00a0+ 0.9P<\/span><sub><\/span>PL<\/span><\/sub><\/span>\u00a0+ 1.3P<\/span><sub><\/span>EL<\/span><\/sub><\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                Combination coefficients are specified in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard as:<\/span><\/p>\n

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                • \n

                  \u03a8<\/span><sub><\/span>cP<\/span><\/sub><\/span><\/strong>\u00a0(live + horizontal): 0.9<\/span><\/p>\n<\/li>\n

                • \n

                  \u03a8<\/span><sub><\/span>cW<\/span><\/sub><\/span><\/strong>\u00a0(wind): 0.6<\/span><\/p>\n<\/li>\n

                • \n

                  \u03a8<\/span><sub><\/span>cR<\/span><\/sub><\/span><\/strong>\u00a0(snow\/roof live): 0.7<\/span><\/p>\n<\/li>\n<\/ul>\n

                  For\u00a0<\/span>serviceability limit state<\/span><\/strong>\u00a0design in\u00a0<\/span>racking design<\/span><\/strong>, all load factors are taken as 1.0.<\/span><\/p>\n

                  H2: Temperature Effects in Racking Design<\/span><\/h3>\n

                  The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard also addresses thermal effects. For rack-clad structures with temperature zone lengths exceeding 220 meters, temperature effects must be considered<\/span>. For bolted or plug-in connection systems, the temperature effect may be reduced by a factor of 0.35, as these connection types provide some degree of temperature stress relief<\/span>.<\/span><\/p>\n

                  \"Steel
                  Steel Racking Components And Cold Formed Columns Showcasing Material Selection For Proper Racking Design Per Specifications<\/figcaption><\/figure>\n
                  \n

                  H1: Racking Design Principles and Methodologies<\/span><\/h2>\n

                  H2: General Racking Design Requirements<\/span><\/h3>\n

                  GB\/T 39681-2020 adopts the\u00a0<\/span>limit state design method<\/span><\/strong>\u00a0based on probability theory, expressed through partial factor design expressions<\/span>. For load combinations where\u00a0<\/span>horizontal loads, wind loads, or seismic actions<\/span><\/strong>\u00a0dominate,\u00a0<\/span>second-order analysis<\/span><\/strong>\u00a0is required in\u00a0<\/span>racking design<\/span><\/strong>.<\/span><\/p>\n

                  Load-bearing components in\u00a0<\/span>racking design<\/span><\/strong>\u00a0must be designed for the\u00a0<\/span>ultimate limit state<\/span><\/strong>, which encompasses:<\/span><\/p>\n

                    \n
                  • \n

                    Strength failure of members and connections<\/span><\/p>\n<\/li>\n

                  • \n

                    Fatigue failure<\/span><\/p>\n<\/li>\n

                  • \n

                    Loss of stability in structures and members<\/span><\/p>\n<\/li>\n<\/ul>\n

                    Non-load-bearing components in\u00a0<\/span>racking design<\/span><\/strong>\u00a0may be designed based on construction requirements.<\/span><\/p>\n

                    H2: Column and Upright Frame Design in Racking Design<\/span><\/h3>\n

                    H3: Average Design Strength for Non-Perforated Members<\/span><\/h4>\n

                    For non-perforated members in\u00a0<\/span>racking design<\/span><\/strong>, the average design strength (f<\/span><sub><\/span>n<\/span><\/sub><\/span>) may be calculated using the following formula:<\/span><\/p>\n

                    f<\/span><sub><\/span>n<\/span><\/sub><\/span>\u00a0= f<\/span><sub><\/span>y<\/span><\/sub><\/span>\u00a0+ (C<\/span><sub><\/span>t<\/span><\/sub><\/span>Nt\u00b2\/A<\/span><sub><\/span>g<\/span><\/sub><\/span>)(f<\/span><sub><\/span>u<\/span><\/sub><\/span>\u00a0– f<\/span><sub><\/span>y<\/span><\/sub><\/span>) \u2264 0.5(f<\/span><sub><\/span>u<\/span><\/sub><\/span>\u00a0+ f<\/span><sub><\/span>y<\/span><\/sub><\/span>)<\/span><\/strong><\/p>\n

                    Where:<\/span><\/p>\n

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                    • \n

                      f<\/span><sub><\/span>y<\/span><\/sub><\/span><\/strong>\u00a0= nominal yield strength<\/span><\/p>\n<\/li>\n

                    • \n

                      f<\/span><sub><\/span>u<\/span><\/sub><\/span><\/strong>\u00a0= nominal ultimate tensile strength<\/span><\/p>\n<\/li>\n

                    • \n

                      t<\/span><\/strong>\u00a0= design thickness (pre-cold-forming)<\/span><\/p>\n<\/li>\n

                    • \n

                      A<\/span><sub><\/span>g<\/span><\/sub><\/span><\/strong>\u00a0= gross cross-sectional area<\/span><\/p>\n<\/li>\n

                    • \n

                      C<\/span><sub><\/span>t<\/span><\/sub><\/span><\/strong>\u00a0= forming type coefficient (5 for cold-formed, 7 for other methods)<\/span><\/p>\n<\/li>\n

                    • \n

                      N<\/span><\/strong>\u00a0= number of 90\u00b0 bends with radius \u2264 5t<\/span><\/p>\n<\/li>\n<\/ul>\n

                      This formula accounts for the\u00a0<\/span>strength enhancement<\/span><\/strong>\u00a0that occurs during cold-forming, where the bending process work-hardens the steel at corners. This is a distinctive feature of the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard that recognizes the unique properties of cold-formed steel sections.<\/span><\/p>\n

                      H3: Column Loading Patterns in Racking Design<\/span><\/h4>\n

                      For column design in\u00a0<\/span>racking design<\/span><\/strong>, two primary loading patterns must be considered:<\/span><\/p>\n

                      Pattern (a)<\/span><\/strong>\u00a0: All beams fully loaded except one beam near mid-height of the lowest level (empty)<\/span><\/p>\n

                      Pattern (b)<\/span><\/strong>\u00a0: For racks with vertical tie rods, a single-curvature bending pattern must also be considered<\/span><\/p>\n

                      Pattern (c)<\/span><\/strong>\u00a0: If the first beam is near ground level, the second-level beam is considered unloaded<\/span><\/p>\n

                      H3: Effective Cross-Sectional Area in Racking Design<\/span><\/h4>\n

                      Column design in\u00a0<\/span>racking design<\/span><\/strong>\u00a0relies on the\u00a0<\/span>effective cross-sectional area (A<\/span><sub><\/span>eff<\/span><\/sub><\/span>)<\/span><\/strong>\u00a0, which accounts for\u00a0<\/span>post-buckling strength<\/span><\/strong>\u00a0of plate elements<\/span>. Two distinct effective areas are defined in the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard:<\/span><\/p>\n

                        \n
                      • \n

                        Effective cross-sectional area (A<\/span><sub><\/span>e<\/span><\/sub><\/span>)<\/span><\/strong>\u00a0: Considers post-buckling strength without deducting holes<\/span><\/p>\n<\/li>\n

                      • \n

                        Effective net cross-sectional area (A<\/span><sub><\/span>en<\/span><\/sub><\/span>)<\/span><\/strong>\u00a0: Considers post-buckling strength with holes deducted<\/span><\/p>\n<\/li>\n<\/ul>\n

                        These areas may be determined by finite element analysis or through\u00a0<\/span>short column testing<\/span><\/strong>\u00a0(see Section 7.3). For A<\/span><sub><\/span>e<\/span><\/sub><\/span>, unperforated specimens are used; for A<\/span><sub><\/span>en<\/span><\/sub><\/span>, perforated specimens representative of actual columns are required<\/span>.<\/span><\/p>\n

                        H3: Buckling Calculation Length in Racking Design<\/span><\/h4>\n

                        The\u00a0<\/span>buckling calculation length (l)<\/span><\/strong>\u00a0in\u00a0<\/span>racking design<\/span><\/strong>\u00a0is determined as\u00a0<\/span>l = K \u00d7 L<\/span><\/strong>, where L is the length between supports in the relevant buckling mode.<\/span><\/p>\n

                        In the rack frame plane:<\/span><\/strong><\/p>\n

                          \n
                        • \n

                          Generally,\u00a0<\/span>K = 1.0<\/span><\/strong>,\u00a0<\/span>l = h<\/span><\/strong>\u00a0(where h is the beam spacing)<\/span><\/p>\n<\/li>\n

                        • \n

                          K = 0.9<\/span><\/strong>\u00a0may be used when all of the following conditions are met:<\/span><\/p>\n

                            \n
                          1. \n

                            Single brace connects to both flanges of the column<\/span><\/p>\n<\/li>\n

                          2. \n

                            Brace eccentricity satisfies the requirements<\/span><\/p>\n<\/li>\n

                          3. \n

                            Columns have base plates<\/span><\/p>\n<\/li>\n

                          4. \n

                            The floor is concrete<\/span><\/p>\n<\/li>\n<\/ol>\n<\/li>\n<\/ul>\n

                            Perpendicular to the rack frame (with vertical tie rods):<\/span><\/strong><\/p>\n

                              \n
                            • \n

                              Generally,\u00a0<\/span>K = 1.0<\/span><\/strong>,\u00a0<\/span>l = h<\/span><\/strong><\/p>\n<\/li>\n

                            • \n

                              If beam spacing h<\/span><sub><\/span>p<\/span><\/sub><\/span>\u00a0exceeds h, then\u00a0<\/span>l = h<\/span><sub><\/span>p<\/span><\/sub><\/span><\/strong><\/p>\n<\/li>\n<\/ul>\n

                              Perpendicular to the rack frame (without vertical tie rods):<\/span><\/strong><\/p>\n

                                \n
                              • \n

                                Generally,\u00a0<\/span>K = 1.7<\/span><\/strong>,\u00a0<\/span>l = K \u00d7 h<\/span><\/strong><\/p>\n<\/li>\n

                              • \n

                                The K value may also be determined through more detailed calculation considering beam-column joint stiffness (k<\/span><sub><\/span>b<\/span><\/sub><\/span>), base stiffness (k<\/span><sub><\/span>u<\/span><\/sub><\/span>), and structural dimensions<\/span><\/p>\n<\/li>\n<\/ul>\n

                                For overall rack frame stability in racking design:<\/span><\/strong><\/p>\n

                                  \n
                                • \n

                                  K values depend on load centroid location:<\/span><\/p>\n

                                    \n
                                  • \n

                                    Below H\/2: K = 1.1<\/span><\/p>\n<\/li>\n

                                  • \n

                                    Below 2H\/3: K = 1.6<\/span><\/p>\n<\/li>\n

                                  • \n

                                    Above 2H\/3: K = 2.0<\/span><\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                                    H2: Beam Design in Racking Design<\/span><\/h3>\n

                                    H3: Load Distribution in Beam Racking Design<\/span><\/h4>\n

                                    Beam loads in\u00a0<\/span>racking design<\/span><\/strong>\u00a0are typically treated as\u00a0<\/span>uniformly distributed<\/span><\/strong>. For cases where this assumption does not hold, the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard provides coefficients (\u03b2<\/span><sub><\/span>m<\/span><\/sub><\/span>\u00a0for moment, \u03b2<\/span><sub><\/span>\u03b8<\/span><\/sub><\/span>\u00a0for rotation, \u03b2<\/span><sub><\/span>a<\/span><\/sub><\/span>\u00a0for deflection) to convert actual load arrangements into equivalent uniformly distributed loads.<\/span><\/p>\n

                                    H3: Design Moment in Racking Design<\/span><\/h4>\n

                                    When beam-column joint stiffness (k<\/span><sub><\/span>b<\/span><\/sub><\/span>) is determined through testing (Section 7.5), the design moment at mid-span (M<\/span><sub><\/span>sd<\/span><\/sub><\/span>) in\u00a0<\/span>racking design<\/span><\/strong>\u00a0is calculated as:<\/span><\/p>\n

                                    M<\/span><sub><\/span>sd<\/span><\/sub><\/span>\u00a0= (W<\/span><sub><\/span>s<\/span><\/sub><\/span>L\/8)\u03b2<\/span><sub><\/span>m<\/span><\/sub><\/span>[1 – (2\/3\u03b2<\/span><sub><\/span>b<\/span><\/sub><\/span>)\/(\u03b2<\/span><sub><\/span>m<\/span><\/sub><\/span>(1 + 2EI<\/span><sub><\/span>b<\/span><\/sub><\/span>\/(k<\/span><sub><\/span>c<\/span><\/sub><\/span>L)))]<\/span><\/strong><\/p>\n

                                    Where k<\/span><sub><\/span>c<\/span><\/sub><\/span>\u00a0= k<\/span><sub><\/span>b<\/span><\/sub><\/span>\/(1 + k<\/span><sub><\/span>b<\/span><\/sub><\/span>h\/(3EI<\/span><sub><\/span>c<\/span><\/sub><\/span>))<\/span><\/p>\n

                                    This formula accounts for the\u00a0<\/span>semi-rigid behavior<\/span><\/strong>\u00a0of beam-to-column connections, which significantly influences moment distribution in racking frames. This is a sophisticated aspect of the\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard that recognizes the unique connection behavior in cold-formed steel systems.<\/span><\/p>\n

                                    H3: Beam Deflection in Racking Design<\/span><\/h4>\n

                                    Similarly, the maximum deflection (\u0394<\/span><sub><\/span>max<\/span><\/sub><\/span>) in\u00a0<\/span>racking design<\/span><\/strong>\u00a0is calculated as:<\/span><\/p>\n

                                    \u0394<\/span><sub><\/span>max<\/span><\/sub><\/span>\u00a0= (5W<\/span><sub><\/span>ser<\/span><\/sub><\/span>L\u00b3\/384EI<\/span><sub><\/span>b<\/span><\/sub><\/span>)\u03b2<\/span><sub><\/span>d<\/span><\/sub><\/span>[1 – (0.8\u03b2<\/span><sub><\/span>b<\/span><\/sub><\/span>)\/(\u03b2<\/span><sub><\/span>d<\/span><\/sub><\/span>(1 + 2EI<\/span><sub><\/span>b<\/span><\/sub><\/span>\/(k<\/span><sub><\/span>c<\/span><\/sub><\/span>L)))]<\/span><\/strong><\/p>\n

                                    H2: Base Plate Design in Racking Design<\/span><\/h3>\n

                                    Each column in\u00a0<\/span>racking design<\/span><\/strong>\u00a0must be provided with a\u00a0<\/span>base plate<\/span><\/strong>\u00a0and a clear anchorage method<\/span>. The\u00a0<\/span>racking design<\/span><\/strong>\u00a0standard provides an approximate design method for\u00a0<\/span>axially loaded<\/span><\/strong>\u00a0base plates. For combined axial and bending loads, testing per Section 7.6 is required.<\/span><\/p>\n

                                    The effective base plate area (A<\/span><sub><\/span>b<\/span><\/sub><\/span>) in\u00a0<\/span>racking design<\/span><\/strong>\u00a0assumes uniform pressure distribution over the effective area. The effective width (e) is:<\/span><\/p>\n

                                    e = t<\/span><sub><\/span>b<\/span><\/sub><\/span>\u221a(f<\/span><sub><\/span>y<\/span><\/sub><\/span>\/(3f<\/span><sub><\/span>c<\/span><\/sub><\/span>))<\/span><\/strong><\/p>\n

                                    Where:<\/span><\/p>\n