Spot the Difference

KAEG recently completed a project which neatly underlines the importance of being able to look behind the workings of black-box finite element analysis (FEA) software. Perhaps, even more important is the ability to probe and understand the output once you get behind the black-box.  See if you can spot the simplest strengthening scheme that we applied for this failing structure by comparing the left and right image!

We received the telecommunications headframe (left image) and it had been marked as failed. It had been run through some FEA software which showed that structural utilisation was over 100%. We took the results apart, probed every member for loading in 6 degrees of freedom. We were able to pin the issue down to one member which was over-utilised in one direction causing loads to be improperly distributed.

The fix: add a simple bracing strut in the left hand corner of the middle triangle to bring the utilisation down to 80% (right image).

KAEG are at the forefront of providing cost-effective design solutions to over-stressed telecommunication structures to ensure continuous safe operations. Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Fasteners in Telecoms

The element enabling the connection of the two dissimilar materials (steel and concrete/masonry) are fasteners, which resist the tension component of the applied force. The fasteners transfer the applied tension and shear loads to the base material (concrete/masonry) through various mechanisms shown in the attached image. For an efficient and reliable design, we must understand the behaviour of each element forming a post-installed connection.

Mechanical fasteners work via interlock (keying) and friction while chemical fasteners work via adhesive bonding between the fastener and base material. We will discuss more on working principles of post-installed fastening and their failure modes in subsequent blogs.

At KA Engineering Group, we leverage on our extensive experience to design and recommend most efficient fastening solutions for new as well as existing systems in telecom construction.

Contact our expert team at info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Internal Database Makes KAEG Faster, Smarter

KA Engineering Group has just celebrated our 3-year anniversary. Since the business established in 2018, we have treated data as a valuable asset and started to build an internal specialised database including wind speed dataset, ancillary parameters, tower manufacture details, client design specifications and design guidelines for different structures, etc.

Each passing day means that not only do our design capabilities and project experience improve but our internal database becomes bigger, better and smarter. Our in-house database allows our engineering work to be streamlined and standardised so that we can provide our clients with economical and fast turnaround design solutions.

With the help of our database, it is possible that performing a full tower climbdown survey can be eliminated, saving time and cost for clients. If climbdown survey is required, we can also offer guidance and provide KA survey template that lists all design data required for structural analysis to avoid the lack of key information and a costly site revisit. We also have the ability to support the entire construction/modification process of telecom towers and rooftop structures, from survey through to structural design and completion.

KAEG are always passionate in pursuing engineering excellence, best design practice and new technology to provide our customers with cost-effective, reliable and fast turnaround design solutions. Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Why social distancing doesn’t have to mean ‘socially distant’

Last Friday, we celebrated 3 years in business. Building a strong relationship with our team has been vital to our success. The very phrase ‘social distancing’ is a fallacy. We are not being socially distant; we are being physically distant. Now more than ever, people need to come together and working from home does not have to hinder that.

We have put together a shortlist of some useful things we have learnt during this period:

  • Utilise one of the many video-calling services currently available. These services do not purely have to be used for meetings and conferences but can help to create a ‘virtual’ office environment. There are meeting rooms which allow private discussions and meetings to be held, with a main room where staff can socialise and seek the help they need whilst they work. Most importantly, it provides an opportunity for our staff to interact on a daily basis.
  • In the current climate, keep staff mental health and wellbeing at the forefront of what you do. There are many little ways in which you can show that you care. Sending out E-cards is one environmentally friendly way to show staff that you are thinking of them during important celebrations and occasions. Some staff have needed to drop or alter hours, due to extra obligations during the pandemic. By being approachable and understanding, you relieve some of the added stress they may be experiencing. As a result, you will have a happier and more productive workforce.
  • Finally, bring the social aspect of the workplace to the home. During our monthly meeting, we encourage our staff to order in lunch on us. This way we can bring the joy of having lunch together, to the home. We also use this time to do online trivia, quizzes, and games (the favourite so far being online connect four!). There is a plethora of games that can be played online, and it is worth giving them a try. There are even teambuilding activities which have now been brought to the virtual world, such as escape rooms, murder mystery evenings and even remote dinner parties helping colleagues feel connected and part of a team.

KA Engineering Group continues to provide uninterrupted structural engineering consultancy for our clients during these disrupted times. Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

KAEG Publications

Title: Fitness-for-purpose assessment of cracked offshore wind turbine monopile

Journal:  Marine Structures

Date: January 2021

Author: Ayodele Fajuyigbe*, F. Brennan

Link: Read here


Title: Detailed Approach for the Assessment of Accumulated Wellhead Fatigue

Conference: Offshore Europe

Date: September 2015

Author: Kingsley Sunday*, P. Ward, C.Griffin

Link: Read here


 

Note

KAEG personnel are the lead authors for the publications listed on this page. * identifies the KAEG personnel

 

Merry Christmas from KAEG

We at KAEG believe that you should share what you have even when little and watch it multiply.  So even though it has been a tough year for all, as is customary for us at this time of the year, we tried to spread a little cheer. KAEG visited South Belfast Foodbank and Faversham Foodbank to support families and individuals that have been hard hit by the Year 2020.

As a result of the Pandemic, the Trussell Trust report a soaring 81% increase for emergency food parcels from Foodbanks, including a 122% rise in parcels given to children. The travel through 2020 has been a particularly unchartered journey for many if not all, leaving families with irreparable losses. We hope and pray that the Year 2021 will usher in healing and restoration from the impact of Year 2020.

We wish a Merry Christmas 2020 and a Happy New Year 2021 to our brilliant workforce, wonderful clients, families, friends, and our struggling neighbours who at this time find themselves dependent on the network of 428 Foodbanks and other forms of support to survive.

2D and 3D Headframe Analysis

Due to our extensive in-house structural design capabilities and experience, KA Engineering Group has been awarded many more headframe projects this year.

Headframes are built up steel structures carrying multiple telecommunication equipment supported on various primary structures, like monopole, stub tower and, lattice tower. They come in varying shapes including turret, triangular, square, hexagonal and circular headframes.

The structural analysis of a headframe may be performed using 2D or 3D finite element methods. 3D analysis is computationally expensive and can involve lengthy engineering man-hours. 2D analysis can be fast and effective, however, it requires comprehensive understanding of the whole structure so that a complex structure can be broken down into simpler parts that can be analysed using 2D method.

Furthermore, 2D analysis, in most cases, depends on significant assumptions in order to simplify the model, which potentially results in more onerous analysis results and may cause structure failure in analysis.  3D finite element analysis of headframe is able to capture the behavior of the whole structure at the level of each element and allow for better load distribution, which leads to more realistic and accurate predictions. KAEG structural team have delivered numerous headframe projects and we can use our expert knowledge to select the appropriate method for your application.

KAEG are always passionate in pursuing engineering excellence, best design practice and new technology to keep pace with increased industrial demand and provide our customers with cost-effective, reliable and fast turnaround design solutions. Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Impact of Feeder Arrangement

Feeder cables can FAIL a lattice tower, through exceeding the structural utilisation capacity, if not arranged thoughtfully. Carefully planned feeder arrangement in a simple system can reduce the utilisation of the lattice tower legs by 15% and reduce the tower brace utilisation by nearly 40%!

Without adequate forethought, a telecommunication system with 16 feeder cables on a tower may be arranged in stacks of 1 or 2. This leads to wind load across eight, or even 16 feeder surface areas.

We investigated the effect of feeder arrangements on tower utilisation. We placed four antennas at the top of an existing 30m square lattice tower, fed by 16 typical sized feeders in a variety of different arrangements. To replicate a common tower arrangement, the structure also included a ladder mounted on one of the tower faces.

What We Found

Our analyses showed the maximum tower utilisation with the feeders stacked in a single row of 16, mounted on one leg, adjacent to the ladder location. Minimum utilisation was from feeders stacked in rows of four, mounted on a leg that is not directly supporting the ladder.

The difference in structural utilisation between these two scenarios was 15% for the tower legs, and 38% for the tower braces!

A surprising find was the structural utilisation from the feeders separated into groups of four, stacked in rows of two, mounted on each leg. The leg and brace utilisation were greater than those in the minimum scenario by 5% and 6% respectively.

Take Away Message

Feeders must be arranged with tower loading in mind. With less loading from feeders, more ancillaries can be placed on the tower, resulting in a more useful AND more financially profitable structure.

Check your existing towers. Check your proposed towers. Think about how the feeders are, or are proposed to be, arranged:

  • Are the feeders helping to distribute the loads more evenly throughout the tower?
  • Are the feeders stacked in the most efficient manner to reduce wind load on the structure?

KAEG continues to leverage our expertise to maximise the structural potential of your asset. Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Structural Analysis of a Tower Array

At KA Engineering Group, we recently completed a project involving the structural analysis of a sequence of towers supporting netting enclosing a sports complex to ensure that the structures could withstand the wind and weight loading on the, tower, connecting wires and netting, protecting the public from stray balls.

The towers are connected as an array, so it is important to analyse the full connected structure to properly define the system response. However, analysing a large number of lattice towers in a single finite element analysis is complex and computationally expensive. To simplify, we completed preliminary analysis by replacing the lattice towers with single poles. We had to ensure that the poles were representative of the global behaviour of the individual towers. The closer the poles are to the towers, the more analogous the global interaction between the actual tower sequence.

We determined the global properties such stiffness, deflection, of each individual lattice tower. The structural characteristics of the poles (main inner and outer diameters) were iteratively refined until the pole and lattice tower responses were equal. The benefit of continuous refinement is greater accuracy. Using the resulting loads (forces, moments) from the sequence analysis of the poles, we were able to assess then perform detailed analysis of each lattice tower.

Using poles in the sequence analysis allowed us to deliver the project in good time to the client. At KA Engineering Group, we continue to push boundaries, developing new and unique ways to tackle structural issues and advancements in a range of applications. The dynamic nature of the development in our company sets us apart from our competition as we are always seeking to improve existing methods.

Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.

Brace Supports for EMA Poles

In wall mounted pole structures, the design loads on ancillaries, i.e. wind load and vertical gravitational loads, are transferred to the walls through the anchors.The anchor pull-out load is limited by anchor and wall capacity. In the event of pull-out load being higher than anchor capacity, internal load bearing back plates can be installed. But if the pull-out load is higher than the wall capacity, a different strategy is adopted to redistribute the loads.

At KA Engineering Group, we have recently analysed and proposed diagonal bracing in wall mounted pole structures at two sites to reduce the cantilever overhang causing high anchor pull loads and posing risk to the primary structure (the wall). The braces are designed to reduce the dynamic loads on wall by redistributing the loads to rooftop. This design also optimises the primary pole and wall brackets and results in a cost-effective solution. If the primary pole is mounted near the corner of wall, the braces can also be installed to secondary wall mounted poles in two orthogonal directions.

KA Engineering Group not only completes structural due diligence for all telecommunication support structures, we also take further responsible steps to consider, advise, and optimise each site, ensuring cost effective design, installation, and maintenance for build contractors and efficient utilisation for operators.Contact our expert team at: info@ka-engroup.com to learn more and discuss how we can best serve your needs.