Weight optimization of steel lattice transmission towers based on Differential Evolution and machine learning classification technique

Transmission towers are tall structures used to support overhead power lines. They play an important role in the electrical grids. There are several types of transmission towers in which lattice towers are the most common type. Designing steel lattice transmission towers is a challenging task for structural engineers due to a large number of members. Therefore, discovering effective ways to design lattice towers has attracted the interest of researchers. This paper presents a method that integrates Differential Evolution (DE), a powerful optimization algorithm, and a machine learning classification model to minimize the weight of steel lattice towers. A classification model based on the Adaptive Boosting algorithm is developed in order to eliminate unpromising candidates during the optimization process. A feature handling technique is also introduced to improve the model quality. An illustrated example of a 160-bar tower is conducted to demonstrate the efficiency of the proposed method. The results show that the application of the Adaptive Boosting model saves about 38% of the structural analyses. As a result, the proposed method is 1.5 times faster than the original DE algorithm. In comparison with other algorithms, the proposed method obtains the same optimal weight with the least number of structural analyses.

Design of lattice towers from hot-rolled equal leg steel angles

Τα προφίλ γωνιακών διατομών χρησιμοποιούνται από τα πρώτα χρόνια των χαλύβδινων κατασκευών λόγω της εύκολης μεταφοράς τους και της επί τόπου συναρμολόγησής τους. Ωστόσο, παρουσιάζουν συγκεκριμένα χαρακτηριστικά που τα διαφοροποιούν από τους άλλους τύπους κοινών διατομών, γεγονός που οδηγεί αναπόφευκτα στην ανάγκη ανάπτυξης ειδικών κανόνων σχεδιασμού. Σε πρώτη φάση ελέγχθηκαν και αξιολογήθηκαν οι υφιστάμενες ευρωπαϊκές διατάξεις για τα ισοσκελή γωνιακά θερμής έλασης, και στη συνέχεια, διεξήχθησαν εκτεταμένες πειραματικές, αναλυτικές και αριθμητικές μελέτες ώστε να προταθεί ένα ολοκληρωμένο και πλήρως επικυρωμένο σύνολο κανόνων σχεδιασμού που να καλύπτει όλες τις πτυχές του σχεδιασμού των γωνιακών. Οι κανόνες αυτοί περιλαμβάνουν την ταξινόμηση της διατομής, την αντοχή της διατομής για όλους τους τύπους φόρτισης, καθώς και κανόνες για το σχεδιασμό μελών υπό μεμονωμένες ή και συνδυασμένες εσωτερικές αξονικές δυνάμεις και ροπές. Όλοι οι προτεινόμενοι κανόνες είναι γραμμένοι υπό την μορφή των διατάξεων του Ευρωκώδικα 3, ώστε να είναι δυνατή η άμεση ενσωμάτωσή τους στην επερχόμενη έκδοση. Επιπλέον, τα γωνιακά προφίλ χρησιμοποιούνται ευρέως σε δικτυωτούς πύργους και ιστούς για τηλεπικοινωνιακούς σκοπούς ή για τη μεταφορά ηλεκτρικής ενέργειας. Τέτοιοι τύποι πύργων σχεδιάζονται κυρίως σύμφωνα με τα πρότυπα EN 1993-3-1 και EN 50341-1, βάσει μιας γραμμικής ελαστικής ανάλυσης πρώτης τάξεως όπου η κατασκευή προσομοιώνεται ως ένα δικτύωμα. Στην παρούσα εργασία πραγματοποιείται αξιολόγηση της τρέχουσας προσέγγισης σχεδιασμού, όπου ο πύργος προσομοιώνεται με ένα λογισμικό μη γραμμικών πεπερασμένων στοιχείων, λαμβάνοντας υπόψη τις αρχικές ατέλειες στην κατασκευή καθώς και τις μη γραμμικότητες του υλικού και της γεωμετρίας. Υπογραμμίζεται η σημασία των φαινομένων δευτέρας τάξεως στην ανάλυση, ενώ επισημαίνεται η ύπαρξη μιας μορφής αστάθειας που δεν καλύπτεται άμεσα από τους κανονισμούς και ως εκ τούτου, συνήθως δεν ελέγχεται. Στην συνέχεια, δύο αναλυτικά μοντέλα για την πρόβλεψη του κρίσιμου φορτίου του νέου τρόπου λυγισμού προτείνονται και επικυρώνονται αριθμητικά. Και τα δύο προτεινόμενα μοντέλα είναι εύκολα στην εφαρμογή τους και μπορούν να καλύψουν το κενό στις υπάρχουσες συστάσεις σχεδιασμού για δικτυωτούς πύργους.

Damping estimation using free decays response in short telecom structures

The constant changes to which telecommunications have accustomed us in recent decades oblige a similar adaptation in other branches of engineering. Structures such as monopoles and short lattice towers are becoming increasingly wind-sensitive and dynamically active with the introduction of 5G technology, which will require new larger and heavier antenna equipment. Expert consultants agree the need to revise the current accounting for structural damping that has not changed in design codes after more than 30 years. A complete set of full-scale field tests is presented to obtain reliable structural damping values in short communications structures. The described methodology analyses free-decaying responses obtained after excitation of the main analysed cantilevered modes in the time domain. A standardized acquisition system based on local accelerometers and an external innovative system using the Video GaugeTM system are required to obtain the desired responses, which use curve-fitting and the eigensystem realization algorithm to estimate modal properties such as the corresponding modal structural damping. The results obtained using the presented methodology agree on higher values of structural damping for both damping estimators and perfectly converge with consultant feedback, which suggested over-conservative (i.e. low) values of structural damping as compared to the conventional values used in civil engineering.

Influence of external loads to wind turbine tower

One of the most important parts of a wind turbine is a tower. There are various designs of the wind turbine towers, and they are most often made of steel pipes, lattice towers or concrete towers. In order to increase energy density to meet the growing electricity needs, larger wind turbine projects have been developed. Larger wind turbine towers can generate more electricity, but such large sizes also create higher costs in terms of development and maintenance. This research sets up a model of a wind turbine tower, where the load to the tower is calculated by its relation to the wind velocity. Analytical approach coupled with a finite element method (FEM) is used to analyse the distribution of tower stresses under these loads. The fatigue analysis of the column is performed using the load from its own weight, the weight of the housing and the distribution of the wind velocity. The effects of different loads are also compared. The results show that the main loads of the tower are the wind force acting on the area of ??rotation of the wind turbine blades and the moment caused by the uneven wind velocity. Construction is modelled using SolidWorks modelling package, where the analysis was performed using FEM in ANSYS software. As a result of the analysis, the stress distribution in the support was determined and compared with analytical calculations.

Grow or successfully disengage? Navigating the revolution of South African tower companies

Subject area of the teaching case: The case is suitable for strategy or entrepreneurship modules. It is designed to teach students about the importance of implementing formal processes when entering a growth phase as well as the complexities, unexpected costs, and benefits that growing a business can bring. Student level: The case is aimed at MBA or Master-level students or executive education programmes as part of a strategy or entrepreneurship module. Brief overview of the teaching case: Lattice Towers is a South African company in the telecommunications infrastructure sector. They are struggling to generate sufficient cash flow to sustain operations as a result of poor strategic decision-making regarding tower-build site acquisition. To compound matters, the owner has been struggling with health issues related to the stress caused by the crises that Lattice Towers is going through. Recently, however, a multinational publicly listed behemoth in the telecommunications industry, Helios Towers, offered to acquire the company. The acquisition offer seems like a saving grace to the owner; however, Lattice Towers is deeply personal to the him and he would not like to lose the brand. Furthermore, there is a tremendous opportunity for business growth due to the imminent increase in demand for tower infrastructure. But based on the challenging financial position the business currently finds itself in, he might not have the option to keep the business. Expected learning outcomes: To develop a decision-making framework and strategy to navigate the business life-cycle stages, from survival to growth Understand the concepts of uncertainty, risk, and liquidity premiums that apply to entrepreneurship Understand the stress-related implications for entrepreneurs Understand the psychological costs and benefits of entrepreneurship Understand the personal financial implications for entrepreneurship