Project Details

Introduction, Open problems and Objectives of the project

A warehouse is a building where massive amount of goods can be stored before their “large distribution” to the consumers. Due to increasing mass production of goods and increasing consumption levels, demand for storage space increases. As the land becomes everyday more valuable in terms of both economy and environment, highly optimized, reliable and safe warehouses are needed. Reduced running costs, automation and larger sizes are the future trends of the warehouse sector.

At present, Automated Rack Supported Warehouses (ARSW) or clad rack warehouses are usually built by manufacturers specialized in structural systems for logistics with the same or similar cold formed profiles used for warehouse storage pallet racks although in the case of ARSW the rack forms the load bearing structure of the whole building by itself. ARSWs can be much larger and taller with respect to usual pallet rack systems. They can be more than 40 m tall, 100 meters wide and 150 meters long.

Main advantages offered by Automated Rack Supporting Warehouses are:

- Significant cost savings in construction as no additional warehouse building is required.

- Short construction periods.

- Roof and cladding are directly fixed to the rack structure.

- Storage in height: Maximum use of available surface area for a high storage density.

- ARSW system is adjustable and eventually demountable.

- They can be fully automated which increases the efficiency of storage and logistics.

- Reduced responsibility for the owner of storage system as the system is assembled as a whole (building + storage).

- Energy efficiency, less carbon foot-print (less heating).

- No interference of rack with the building columns or the building vertical bracing system. Especially in high seismic zones this eliminates the need for seismic separation detailing between building and rack structure.

- Reduction of workers needed inside the warehouse.

The number of such warehouses is rapidly increasing, therefore an efficient and safe design methodology/approach for ARSWs becomes a major concern.



In Europe (and in the world) an official standard reference document for the design of Automated Rack Supported Warehouses is presently missing. Designers are obliged to work with a total lack of references and of commonly accepted design rules and procedures and the design of ARSW is very often based more on personal experience rather than on sound principles and rules supported by experimental evidence and theoretical studies.

To design this type of highly sophisticated structures, main references are:

- Building codes (like Eurocodes), which however do not take into account particularities of self-supporting warehouse structures

- Recommendations for steel storage racks, which are produced according to the analysis and tests of the racking systems, which are, however, quite different from ARSW.

Unfortunately, Automated Rack Supported Warehouses are not standard buildings and need specific design rules and construction methods and tolerances.



Basing on an accurate evaluation of safety level of the design concepts actually adopted in current practice in the totally absence of specific Design Codes, the main objective of the proposal is the definition of dedicated innovative design approaches for ARSWs in not seismic and seismic conditions. In particular, attention will be focused on loading conditions that characterize the ARSWs during its installation and service life and on ductile design under seismic loading. Based on such analysis specific design rules and recommendations will be carried out for erection and design of ARSWs.

In particular, the following open problems will be investigated for the first time in Europe and in the World:

- Typological and functional analysis of typical ARSW structures based on needs/demands and practice of the logistics industry. In fact, since the design of ARSWs is strictly connected to specific logistic requirements, there is a wide range of functional typologies worldwide. Thus, a clear and exhaustive classification of these particular structures will be developed, based on structural typologies and functions connected to logistics needs.

- Identification of critical erection phases and relevant design rules for a safe construction of warehouses.

- Characterization and evaluation of wind loads on ARSWs.

- Definition of pressure coefficient and global wind action on the trussworks and on the partially cladded structure during the erection phase.

- Identification of the relevant distributions of storage goods due to the logistic load strategies for different ARSW typologies.

- Investigation of the implications of the logistic loading strategies on the structural response of ARSW to wind and earthquake loading.

- Identification of characteristic loading conditions and of combinations factors of variable actions to be considered in the design phase.

- Identification of combination rules of loads during the life of the structure, as affected by the distribution of the masses.

- Definition of guidelines for serviceability and ultimate limit state checks with reference to particular storage conditions and loads, both in static and seismic scenarios.

- Investigation of the different results obtained from simplified and 3D numerical analysis so developing a correct modelling procedure for ARSW.

- Analysis of alternative partial yielding patterns for seismic design of ARSWs in under low/moderate and high seismic loadings.

- Calibration of suitable capacity design rules, overstrength factors and q-factor for seismic design of ARSWs.

- Definition of guidelines for seismic design of ARSWs.


Organization of the Project - Work Packages

The project is organized in the following Work Packages:

  1. WP1 - FUNCTIONAL AND TYPOLOGICAL ANALYSIS OF ARSW STRUCTURES and DESIGN OF CASE STUDY BUILDINGS.

Responsible: Noega Systems S.L.

In the WP1, an accurate functional and typological classification of typical ARSW structures will be carried out analysing structural typologies and related functions connected to logistics needs. On the basis of such classification design input for case studies will be defined and, consequently, design of case studies according to current practice will be carried out with reference to different types of structural schemes and structural elements (steel profiles, joints, bracing, column base …) adopted in design by industrial partners. Erection phases will be carefully studied and defined. Since, actually, the majority of ARSW structures of practical interest belong to the two following main categories, after the general and complete classification of ARSW buildings and the determination of their all features, particular attention will be paid to (see form B.2 WP1): a) Automated double depth cranes, b) Automated multi depth shuttle. Three levels of seismic hazard will be considered in the design of case study buildings that will be executed by the five Industrial Partners (IPs) involved in the proposal: no seismic action; low seismicity level (0.10÷0.15 g); moderate/high seismicity level (0.25÷0.30 g). Case studies, accurately designed by the 5 IPs for the 2 considered structural typologies and the 3 levels of seismic hazards (for a total of 30 case-studies), will be the base for all the subsequent studies performed in the following WPs.


  1. WP2 - WIND LOADS EFFECTS DURING ERECTION PHASES.

Responsible: University of Florence.

In the WP2 critical configurations for wind loading during erection phases will be identified. To this purpose specific erection phases of the various case studies will be selected to be tested in the wind tunnel by means of dedicated numerical analyses. Based on suitably designed wind tunnel tests executed by University of Florence, erection phases will be optimised, relying on accurate wind load measurements, and simplified load patterns to be used as pre-normative tools for the design of ARSW structures will be set up. Results o WP2 will be the base for numerical analyses carried out in WP4 and for further evaluations executed in WP6.


  1. WP3 - LOADING MODELS VS. LOGISTIC NEED.

Responsible: System Logistics S.p.A.

In the WP3, basing on available information on logistic strategies for each warehouse typology, gravity load distribution and its probability of occurrence will be analysed in order to better define related design values. On this basis, main loading models for each relevant storage strategy and following combination factors of variable actions will be identified. At last, suitable design rules and loading combinations referring to relevant limit states will be determined. Loading models and consequent mass distribution will be the base for the numerical analyses and further elaboration carried out in WP4, WP5, WP6 and WP7 on ARSWs in not seismic and seismic conditions.


  1. WP4 - ANALYSIS OF STRUCTURAL RESPONSE UNDER EARTHQUAKE OR WIND LOADING.

Responsible: National Technical University of Athens.

Basing on a suitable protocol, nonlinear analyses on ARSW case study buildings will be executed. Numerical modelling and analysis of the structural response of designed ARSW case study buildings will be carried out for the three situations of non-seismic action, low/moderate and high seismic action. Basing on numerical results, behaviour factor (q-factor) for designed warehouses will be evaluated and simplified 2D modelling approaches for the analysis warehouses in not seismic/seismic conditions will be set up. Results of numerical analyses executed in the present WP will be the base for the further analyses and evaluations executed in the WP5 and WP7 in seismic conditions and in WP6 in seismic conditions.


  1. WP5 - DEFINITION OF CAPACITY DESIGN RULES AND CALIBRATION OF Q-FACTORS.

Responsible: University of Pisa.

Basing on numerical results obtained in WP4, the local ductility capacity of dissipative elements (defined in relation to the structural typology of designed case study buildings) and analysis of the influence of local ductility μl on the global structural performance of case study buildings μd will be evaluated, determining also the effective ductility capacity (IP, μd) of ARSW case studies with reference to what assumed in the design phase as well as the effective yielding patterns (YPs) of ARSW case studies with reference to the traditional capacity design approach assumed in the design phase. On this basis, the efficacy of alternative yielding patterns (YPs) with respect to the foreseen global ductility level related to the q-factor assumed in the design will be investigated in order to select 3 alternative partial yielding patterns (YPs) and overstrength factors for each of the earthquake resistant structural solution previously designed. Case study buildings able to develop selected alternative YPs using overstrength factors previously determined will be so re-designed, executing then their performance analyses evaluating effective values of q-factors depending on local ductility level, YPs and overstrength factors. At last experimental tests on 20 substructures will be executed in order to validate the efficacy of proposed of design guidelines. Basing on results of aforementioned studies, it will be possible to calibrate a new dedicated design approach overcoming the difficulties due to the application of actual design rules for standard buildings. Such new design approach will be based on the definition of new capacity design rules related to suitably defined partial yield patterns.


  1. WP6 - DEFINITION OF DESIGN RULES FOR NOT SEISMIC CONDITIONS.

Responsible: Hasselt University.

Results obtained in WP2, WP3 and WP4 will be the base for the improvement of actual design approach for ASRW in not seismic condition; to this purpose, ARSW case study buildings will be re-designed, paying attention to local instability phenomena, optimization of profiles’ section, joint connections during 1) erection phase and 2) serviceability phase. Dedicated guidelines for ARSWs in not seismic condition for the design during erection phase, for the design in the serviceability phase and for the modelling and the analysis (linear and nonlinear) will be arranged. It’s necessary to note that such design guidelines, even if initially developed for the two actually most diffused typologies of ARSW (automated double depth cranes and automated multi depth shuttle) can be easily extended to all the typologies of ARSW buildings classified in WP1.


  1. WP7 - DEFINITION OF SEISMIC DESIGN RULES.

Responsible: Rheinisch-Westfaelische Technische Hochschule Aachen.

Suitable innovative design rules for ARSW buildings in seismic area (both automated double depth cranes and automated multi depth shuttle), including indications regarding definition of limit states, evaluation of significant collapse mechanisms with selected/partial YPs, capacity design rules will be developed basing on results obtained in WP3, WP4 and WP5. Recommendations for the behaviour factor (q-factor) and overstrength factors of ARSW buildings (both automated double depth cranes and automated multi depth shuttle) will be also arranged as well as design rules for the dissipative portions of designed ARSW buildings, including dissipative elements/joints/connections, in order to make them able to achieve selected q-factors. It’s necessary to note that such design guidelines, even if initially developed for the two actually most diffused typologies of ARSW (automated double depth cranes and automated multi depth shuttle) can be easily extended to all the typologies of ARSW buildings classified in WP1.


  1. WP8 - DISSEMINATION AND COORDINATION ACTIVITIES.

Responsible: University of Pisa.

WP8 will be devoted to the organization and to the coordination of the activities foreseen in the project as described in the previous WPs. Moreover, for the success of Project products, it will be fundamental to create a renewed sensibility to the ARSW structural design. To this aim, Project results both on not seismic and seismic design and execution phases will be disseminated as wide as possible to SMEs and National and International Associations of Racking Manufacturers by seminars, websites, newsletters.

Project results will be disseminated during all research period, in order to increase attention of the operators at commercial, technical and scientific level. Such dissemination will be obtained by internet applications (websites of Universities and SMEs, sale-networks, advertising, newsletters), technical reports, papers, conferences and seminars. The possible publication of step-by-step results on social networks in order to share ideas, photos and comments will be analyzed.

Available international experts and/or designers will be also involved in the dissemination activities. Moreover, in order to share the common technical bases for the proper seismic design of steel storage racks, most significant Project results will be shared with the European CEN TC344 -WG5 working group, which is actually finalizing the standard code for design of adjustable pallet racking systems in seismic area (prEN16681). At last, dissemination activities will include a final workshop organized in Italy, in Milano, by University of Pisa with the collaboration of FINCON and MODULBLOK. European and International producers and designers will be invited to participate to the workshop. Members of standardisation bodies at National and International level will be also invited. Results of final workshop will be disseminated at Academic level (Universities) as well as by the Associations of Producers or for the Promotion of Steel Constructions. The workshop will be open to technicians, producers, academics, students and construction companies and representatives of every partner will present their most significant advances, with a number of foreseen attending participants around 200-250.