It is my pleasure to bring you the editorial of the October issue of Structures and Buildings. In this issue, our readership will find one Briefing and five research articles covering topics from facades to seismic behaviour of arch bridges. Once again, the eclectic nature and origin of these excellent scientific contributions highlight the role of civil engineers in all aspects of infrastructure projects, regardless of their nature, size or geographical location.
The construction of medium- and high-rise building blocks is expected to grow significantly in the UK over the next few decades, primarily pushed by the need to tackle historic housing shortages and by the net-zero carbon agenda in construction. Facades in these buildings are to comply with the Building Safety Act 2022 to avoid tragedies as Grenfell Tower. The first contribution of this issue considers how more sophisticated management systems and design tools from infrastructure sectors (specifically rail and nuclear) could translate into the residential facades. The Briefing by Birbeck (2024) provides an excellent insight into the challenges faced by designers and contractors, but it also proposes some practical advice and directions to readers and practitioners working in the field of building design.
In the second contribution of this issue, Al-Rousan and Alnemrawi (2024) present an interesting article that examines the behaviour of thermally shocked reinforced concrete (RC) columns internally confined by auxetic steel wire meshes. In the experiments, different number of internal steel wire meshes (1 to 5 layers) replace the steel stirrups/links typically used in RC columns, whilst a thermal shock of 500°C for 2 h replicate exposure to fire or high temperatures. The results show that the steel meshes improved the ductility, energy absorption and axial capacity of the RC columns, but only if heavy confinement is used (4 and 5 layers). However, the exposure to high temperatures reduced the effectiveness of the mesh confinement at improving the behaviour of the columns. Our readership working in design and strengthening of RC structures will find this article particularly useful.
The remaining four articles in this issue adopt different finite element (FE) approaches to analyse numerically the behaviour of different types of civil engineering structures. Composite sections are extensively used in the construction of buildings and bridges. Al-Dujele and Cashell (2024) conduct comprehensive finite element (FE) analyses to investigate the flexural behaviour of concrete-filled rectangular steel tube beams. In this relatively new type of beams, concrete fills in the tubular top flange of a steel section, which in turn helps to reduce torsional and buckling issues in heavily loaded beam. The detailed FE models are calibrated with third-party tests, and the results between them match very well. The authors also propose a practical analytical procedure to calculate the flexural resistance of concrete-filled rectangular steel tube beams, after which a parametric analysis is conducted to compare the FE and analytical predictions. It is shown that the ultimate moment resistance predicted using the analytical approach is sufficiently accurate and even slightly conservative, thus being suitable for design. Our readership working in composite construction will find this contribution particularly interesting.
The use of AI in structural design and optimisation is becoming more common not only in research but also in practical applications. Lateral torsional buckling is a parameter that very often controls the design of steel I beams. Despite this, current codes rely on (over)simplified equations that tend to be very conservative. The fourth contribution in this issue by Rossi et al. (2024) investigate the lateral torsional buckling of steel I beams via nonlinear FE analyses (including calibration with test results) and parametric analyses. The authors then adopt an Artificial Neural Network (ANN) approach to propose new equations to predict the lateral torsional buckling of steel I beams. It is found that the overall beam slenderness ratio has the highest impact on the lateral torsional buckling resistance. It is also found that, compared to other models proposed in the literature, the ANN-based formulation is more accurate to calculate the lateral torsional buckling of beams.
Readers working in the field of bridge engineering and seismic design are invited to read the contribution by Gholipour et al. (2024). In this article, the authors study the peculiar effects of ‘fling step’ pulses on the seismic response of RC arch bridges. The fling step is a permanent ground displacement caused by the long-period pulse within the frequency content of an earthquake whose effects on structures are not well understood, and in this sense this article provides valuable insights. Three case study bridges from Iran are modelled and analysed in FE software. Seven near-field acceleration records from the PEER database were considered in the study, including records with the fling-step pulse, and others with the fling-step pulse removed. The results show that the fling step can change the response parameters investigated (curvature, curvature ductility demand, drift and deck unseating), and that the change is linked to the ratio of the period of the bridge to that of the fling-step pulse. Whilst the fling step tends to increase the response parameters (e.g. increase in deck unseating by up to 200%), residual displacements were less affected. The complexity of the phenomenon suggests that more research in this area is necessary.
The last article in this issue focuses on foundations of wind turbines, which is a very relevant topic as our countries move on to more environmentally friendly sources of energy to meet their net-zero commitments. The contribution by Yang et al. (2024) examines numerically the behaviour of foundations of prestressed concrete and steel wind turbine towers. The internal force and damage in the foundation under extreme load conditions are studied using the static loading method. Under such conditions, the prestressed reinforcement is found to have limited impact on the local pressure at the anchored end of the foundation. It is also shown that the prestressing prevented concrete cracking and tower deformation. Areas experiencing extreme loads on both sides of the foundation can be designed using the simplified bracket method to obtain forces and amounts of reinforcement. This article should be very appealing to our readership working in the design of wind turbines, foundations and prestressed concrete.
I am sure that the readers of Structures and Buildings will find the above contributions both interesting and useful. As always, the editorial team is open to receive discussions on the above articles, as well as any comments or suggestions you may have.
