Barnabas Ilko

The official link for the call can be found here Temporary works (icevirtuallibrary.com)

Dear TWf CoP members, We received the following message from the TWf UK recently: Civil Engineering is planning a special issue in 2023 on the latest developments in temporary works, one of the most challenging yet least recognised fields of engineering. In addition to providing short-term support and protection for built assets throughout their lifecycle, often on a vast scale, temporary works include non-permanent structures for all kinds of human activity. From field hospitals and demountable stadia to emergency bridges and flood barriers, society has come to depend on the ingenuity of temporary works engineers. Common to most temporary works design is a detailed understanding of often fast-changing load conditions and a need for safe, rapid and sustainable assembly and disassembly. There is also a significant overlap with permanent works design, as structures that are more resilient to temporary loading conditions need less in the way of temporary works. The journal is calling for papers on the latest thinking and practice in temporary works, ranging from innovations in planning, design and monitoring to novel methods, materials and applications. They can be in any relevant engineering field, including structures, marine, geotechnical, transport and process, and for any application, from falsework and formwork to ground support, cofferdams, gantries, jacking systems, conveyers and access platforms. I have attached the slides that were provided with the message. If you are interested in putting forward a paper, please get in touch with me or with the individuals noted on the slides. Once I receive the official call via the ICE webpage, I will post it here. 21 12 10 _ICE TW Special Edition_ TWf_ ASt_Initial notification v 1.pptx

@Anthony McLellan, thank you for the suggestion. We are in the process of gathering information on various types of TW and requirements relating to these structures/equipment by various codes. We have a working document and awaiting the issue of the new wind code as well as the new formwork standard. This event will likely be held in Q4 of 2021.

@Shane Groom, thank you very much for taking the time to review the document. We will incorporate your comments to the document.

We tend to refer to the HSE (BS 5975:2019 Code of practice for temporary works procedures and the permissible stress design of falsework (bsigroup.com), CDM (Construction - Construction Design and Management Regulations 2015 (hse.gov.uk) and BS5975 (BS 5975:2019 Code of practice for temporary works procedures and the permissible stress design of falsework (bsigroup.com) that provide guideline on good practice in the UK. We do not have the equivalent of CDM and BS5975. The procedural control document is usually established by contractors and is driven by previous experience of individuals and organisations. Some clients might require certain TW requirements in the contract and contract documents.

Unfortunately, there is currently no such standard or general guideline (at least none that I know of) that would outline the delineation between temporary and permanent works. Usually it is set by the clients on projects and is passed down to contractors via contracts and contract documentation. This means it can vary from project to project and industry to industry. The best course of action is to negotiate the scope with the client at the beginning of the project. If you would like to gather more information on procedural control, have a look at the free guideline published by TWf NZ (https://secure.chasnz.org/downloads/resources/TemporaryWorksProceduralControl_GPG_.pdf) You can also find more reading on this topic on the TWf UK's webpage. I would highly recommend reading documents in the resources folder (Library - Temporary Works Forum (twforum.org.uk) Lastly, a good Australian based document is the Safe design of structures (Model Code of Practice: Safe design of structures | Safe Work Australia) that outlines the roles and responsibilities of designers. Equally applicable for PW and TW engineers.

@Steve Douce, Shane's response is spot on. You have a few options to choose from and I would recommend looking up the research paper by C H Wang and L Pham as that is the basis of the tables in the ABCB Standard. That particular standard does not cater for all temporary works and you might want to take a different approach, or as suggested, a performance based approach. I have no experience with mobile structures, but I would think the same rules apply as for static structures. If you are using an equipment by a supplier, they should have specification for certain use. If it is custom built, I would use the above advice. I would note one item though. You should assess the risk of the equipment toppling over if the wind picks up before you can fix it down. You should assess what is in the surrounding and if failure of the equipment can lead to other H&S hazards, I would recommend using a higher FoS for overturing.

@Tony Geldart, just a few other items you might want to consider: You will need to consider time and how long the shoring box is going to be used in a particular location You will need to allow for potential water pressure or saturated material you will also need to consider nominal surcharge loads around the trench (this might be stockpiled material, vehicular loading or other) The best would probably be to use a K0 value for the calculation of the pressure (this might lead to higher than 40kPa pressure though) All in all the best option might be to have a table of certain load cases for various depths and have 2, 3 or 4 types of shoring boxes. This might be more economical, easier and compacter to transport and easier to handle on site.

First of all, consider it. I usually revert back to WHS (and OHS) acts that explain designers' primary duty of care. PW designers should have one way of building their design safely. Maybe the builders have better, faster or safer ways, but there should be at least one solution for the build. I am not aware of any legislation that would specifically mandate considerations for TW or constructability/construction staging.

I am not familiar with the geotechnical strength reduction factors in this code. Will leave it up to someone more knowledgeable in this field to respond to this query.

Via good contractual terms and conditions as well as collaborative clients. There is no magic solution here.

Under all circumstances, design work needs to be checked internally. At least this is what I am used to. The level and type of check might vary dependent on the complexity of the task. It does not necessarily have to be a Chartered Engineer. Unfortunately, there is no Chartered Temporary Works Engineer in Australia. I am not saying that the engineer should not be chartered, but their and the company's competency should be queried. To provide greater assurance of the competence of those carrying out temporary works design activities, an internal or industry guideline could be developed to help contractors and subcontractors to choose the right companies and individuals. It should be a competency-based matrix that focuses on temporary works design. The designer and checker should sign off on the design in my opinion. BS5975 has a relatively straightforward approach to this and outlines who needs to be the checker for various design tasks. You can find it in Table 2. See snip below.

A very good first step would be to educate the clients about the potential risks and how it would impact their revenue. That might be a great first step.

I am a little bit confused by the unexpected loads such as temporary storage comment. I assume the question might be related to impact loading on structures from vehicular traffic, load being dropped from floors above if no protection fans are installed below, loads dislodging while lifting with tower crane. Or a usual item we debate which is loading on overhead protections from vertical and lateral loads. In case you are after loads falling on a temporary structure, AS1170.1 should be used as a first step. The commentary will explain how to calculate these forces, simple physics. In case you are after storage and impact loads on falsework, please refer to the Concrete Institute of Australia's practice note Z36 which has a very good explanation of how these loads should be calculated.

As mentioned, in the table time is represented by the design life of both, time allowed for planning, legacy and warranty liabilities and when they lapse. In very short, there is usually more time allowed for the design and planning of PW versus TW.