Earthquake Damage-Prevention Shelving Attachment (EDPSA) Research Report by Richard Clarkson

Earthquake Damage-Prevention Shelving Attachment (EDPSA) Research Report Richard Clarkson 300160220

Summer Research Project:

Earthquake Shelving (Nov 2011- Feb 2012)

Supervisor:

Jeongbin Ok + 64 4 463 6278

jeongbin.ok@vuw.ac.nz Research Assistant: (426 hours)

Richard Clarkson

Faculty:

Faculty of Architecture and Design

+ 64 277474741 clarkson.richard.nz@gmail.com

+ 64 4 463 6200 design@vuw.ac.nz

University:

Victoria University of Wellington + 64 4 472 1000 info-desk@vuw.ac.nz

In Collaboration with:

Precision Shelving (via Henry Smits) + 64 4 920 5400 service@precisionworkspace.co.nz

Patent Pending

Abstract This research is an exploration of damage prevention methods of goods stored in retail shelving units. The research scope spans from initial metric data collection and through to a full scale working prototype of the final design. Much attention has been given to earthquakes in light of the recent Christchurch Earthquakes (Sep 2010, Feb 2011, Dec 2011), with the loss of life and substantial damage to structures and goods seen as a result of these earthquakes it reinforces the importance for adequate preparation and protection. While much research and development is being done in the area of earthquake sensors, response systems and structural supports there is a lack in goods damage-prevention, specifically in small to medium size retail firms who often do not have the monetary resources to properly equip their stores with the current earthquake damage prevention systems. This research is an exploration of such a system that would primarily cater to the needs of this target market. Special thanks must go to Precision Workspace who kindly donated two shelving Bays for testing prototyping.

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Fig. 01 Final Prototype of Earthquake Damage Prevention Shelving Attachment (EDPSA) 3

Introduction Images of the Christchurch earthquakes and indeed other recent earthquake locations worldwide show the most at risk genre of small-medium retail outlets include, but are not limited to, bottle stores, small supermarkets, minimarkets and cafĂŠs. Thus this is the target market of this research and the concepts and designs will be focused on meeting the needs of this group. The needs of the target market that we have arrived at come from a questionnaire survey done locally (see appendix A) and with informal interviews with a representative from shelving providers Precision, Henry Smits. 1234-

Low Cost Functional/Reliable Hidden when not in use Easy of installation/maintenance/testing

I have expressed following formula as the likelihood of a store owner to invest in this design, given that the other variables such as function/reliability, hidden/low interference with shopping activities, and ease of installation, maintenance and testing are all achieved in the design: If P x L

C then YES

If P x L

C then NO

Where perceived probability earthquake (P) x perceived average value of loss (L) is substantially greater than the cost of unit + installation + cost of maintenance (C) then the store owner will see the design as a positive investment and would be more likely to purchase the design (YES). However if it is lower, equal to or even only slightly higher the store owner will see it as a poor investment and will likely not purchase the design (NO). Thus minimising the cost of each unit and additional installation and maintenance costs is essential; however there are three main methods to increase the chances of a store owner purchasing the design. The first and most effective method is to use litigation and law to make it mandatory as with seatbelts in cars, however we are not looking for such a forceful approach as of yet. The second method is to rely on the perceived probability of an earthquake being high as in locations such as Christchurch, but this is an irrelevant argument as although the likelihood of an earthquake can be assumed, earthquakes themselves are too unpredictable. A third method would be to approach the insurance companies and have them offer discounted premiums to clients on stores which had the design installed. This particular method is perhaps the most realistic and cost effective method for all parties concerned, as insurance companyâ&#x20AC;&#x2122;s payout less in the event of an earthquake, clients receive discounts on premiums and have reduced damage in the event of an earthquake and the general public are less at risk from falling goods. If the third method where eventually be put in place then the equation could be simplified to: If D

C then Yes

If D

C then No 4

Where D = insurance premium discount over the midterm, C = all costs associated with the design. Therefore once the project reaches a certain point, perhaps post final working prototype and testing, it is my recommendation that negotiations with insurance companies should commence.

Fig. 02 Collection of images of Wellington local retail shelves (Store names suppressed to preserve animosity) 6

Fig. 03 Image close-up shows valuable product vulnerable to earthquake damage.

Design The main component of the device is a free falling scissor mechanism attached to a horizontal barrier bar. The scissor mechanism features 3 pivot points (one each on the upper shelf attachment, one on the lower barrier bar and one in the center of the two scissor arms) and 2 sliding pivot points (one each on the upper shelf attachment and lower barrier bar). This allows free vertical movement of the barrier bar while maintaining its horizontal level. The pivots are made up of lose rivets, and the sliding pivots made with two different sized washers bolted together, the smaller washer fitting inside the slot and whose thickness is slightly greater than the slot, relieving the friction between the slot and the two larger diameter washers on either side. The upper shelf attachment can screwed, bolted or riveted to most existing shelving using existing standard holes, and is reinforced by bending the steel into a U frame width-wise, with the bottom of the U attaching to the underside of shelf. The other components of the barrier slide into this U frame using a side by side arrangement of the pivots. On the non-sliding pivot side the upper bar (UB) is attached to scissor arm 1 (SA1), which is attached to scissor arm 2 (SA2) at the center, then scissor arm 2 is attached to the barrier bar (BB) (reinforced by bending into an L section width-wise) on the same side as the UB â&#x20AC;&#x201C; SA1 connection. On the sliding pivot side UB is attached to SA2 on a lengthened sleeve as SA1 is slightly shorter than SA2 this lengthened sleeve is unobstructed. SA1 then has a section removed from it to allow a 2nd lengthen sleeve to connect SA2 to BB. Without this feature if the scissor bars would overlap and reduce the streamlined capability of the system. Each slot also has an adjustable height maximum, which consist of a sliding rubber plug secured with a nut and screw bolt and the underside of the barrier bar is fitted with an optional strip of adhesive rubber foam for added protection and for visual aesthetics. The standard length of this barrier system will be 895mm long and can be easily scaled up or down lengthwise to fit various sized shelving units and side-ends of shelving units. To maintain its aesthetic & functional non-intrusive design the barrier system is hidden from view attached on the front underside of each retail shelf, which when activated (see sensor and latch systems below) falls to the predetermined height and restricts goods from sliding forwards off each shelf. An additional option is to spring load the scissor arms allowing the unit to be flipped and attached on top of the top shelf, thus protecting the entire shelving unit. In addition to this main component the device comprises of two other components; a sensor unit and a latch unit. The design of which depends on the version of the device, which can either be; passive, mechanical or electrical. Passive Version In the Passive version the sensor and latch are combined into one unit that operates on the principal of friction. In the loaded (up) position the friction of the barrier bar against the specially shaped and spring-ball loaded housing maintains the barrier bar under normal conditions. When vibrations or lateral movement such as that experienced in an earth quake reach a certain level the friction between the two is overcome and the barrier bar drops. The spring loaded ball allows for adjustment of sensitivity via a screw in the back of the housing. Mechanical Version The mechanical version uses principals developed for an earthquake cupboard door latch. A medium size ball bearing rests in a slightly concave cube. The top of which is also concave and is pivoted on the top front of the cube. In an earthquake the weight of the ball Bering causes it to roll about inside the cube thus offsetting the top which pivots the tiger down momentarily. Using a more streamlined 8

adaptation of this system the trigger activates a very sensitive, offset-spring-loaded latch which pulls the pin holding the barrier bar in the loaded position, thus allowing it to fall. The offset-springloaded mechanism is biased on the principals of a mousetrap using a very small force in one direction to release built up tension in another. Electronic Version The electronic version uses a Quake Alarmtm â&#x20AC;&#x201C; a certified pre-existing earthquake sensing product designed to produce an audible alarm in the event of an earthquake. The alarm utilises a reverse pendulum design to close an electrical circuit powered by a standard 9v Battery. The alarm claims to be activated by the faster traveling P waves of an earthquake giving extra time for people to remove themselves from potentially harmful places & situations before the damage causing S waves arrive. This feature when integrated into the device also provides extra time for the barrier bars on each shelf to fall into position before the goods on the shelves begin to overcome friction and move at all. The alarm also contains an adjustable sensitivity screw to assist in gaining the correct tolerances. For this purpose the Quake Alarmtm has been adapted to feature a switch makes the alarm function optional. A secondary circuit is installed that utilises the alarm sensor as a switch to activate a 433 MHz Radio Frequency Transmitter. The adapted Quake Alarmtm is installed onto a load baring wall in a central location of the store. Each shelving Bay (two sides) is fitted with a circuit featuring a 433 MHz Radio Frequency Receiver and power supply. Each individual shelf is fitted with a 12v Pull Solenoid in each barrier, connected in parallel to the main shelving bay circuit. Once activated by a signal from the transmitter the receiver then acts as a switch which closes the circuit to drive each Solenoid which in turn releases each barrier bar. The Transmitter is set to send a 0.2 second, momentary signal burst ensuring that the entire system operates effectively and reliably.

Fig . 04 Shelving unit pre earthquake simulation.

Fig . 05 Shelving unit post activation.

Fig . 06 Photo collage of the design prototyping process and exploration

Potential Adaptions, Future Explorations and Necessary Development While this stage of the research is complete and a working prototype has been produced there is still opportunities for areas of this project to be developed and adapted. An entirely passive version has been looked at, although this version was not as accurate or reliable as the electromechanical prototype it could provide a cheaper alternative to store owners who are willing to accept a degree of tolerance in terms of reliability in order to achieve a cheaper overall cost. I believe this is a valid direction to develop, even as just a secondary alternative to the main product. Rigorous testing must be done to calculate its exact tolerances though as that data will be crucial to that versions success in the market. Other developments include removing the Aluminium Flat Bar uses for the cross sections of the barrier and replacing it with custom engineered bent steel. This would be relatively simple for an engineer with experience in steel structure reinforcing, for example those working at Precision. The entire unit could be easily scaled down lengthwise to fit smaller shelving units. The unit could have some sort of wire or mesh in between the cross bars and barriers to stop smaller goods from falling through. There is potential for development of an adjustable stopper in each of the slots to set the travel of the lower barrier. The horizontal travel of the lower barrier bar potentially needs to be reinforced further to minimize chances of objects slipping under the lower barrier bar. Further development on more cost effective alternatives to the Pull Solenoid, such as the standard 3v motor and offset slide mechanism that I prototyped earlier on in this research. Currently the design only protects against goods falling off the front of the shelf and assumes that there will be either another shelf at each of the side ends or some other structure to restrict goods falling out. This should be investigated further to validate this assumption. Similarly I have assumed that stopping goods falling is sufficient in order to minimize damages but perhaps this may not be enough. Even though the goods cannot move off the shelf certain goods such as glass wine bottles may shake and bang against each other during the more violent earthquakes and may cause breakages. Thus perhaps research is required to attend to this. A further limitation is that both the transmitter and receiver are battery powered and would require regular testing from the store owner, a representative or a qualified professional. There is potential for either to be connected via an adaptor to mains power and more research should be done to explore this option.

Conclusions There are very few earthquake designs that deal specifically with shelving and still fewer that are attachable to existing shelving units without retrofit. The research, concept and prototype of this design are indeed a step in the right direction towards a viable product that could potentially save hundreds of thousands in damages and loss of goods. Although there is still much research and testing to be completed I have shown that this is credible to expand this research to develop, manufacture and market such a product as an Earthquake Damage-Prevention Shelving Attachment. Thanks to Henry Smits and Precision Workspace, Victoria University of Wellington, the workshop technicians (especially John), engineering advice from David Rycroft, and my a very special thanks to my supervisor Jeongbin OK.

Appendix A â&#x20AC;&#x201C; Information sheet and Consent form Samples

Appendix B Sketches and working Diagrams

Appendix C Process Snapshots