With rapid urbanization, population growth and anthropogenic activities, an increasing number of major cities across the globe are facing severe urban heat islands (UHI). UHI can cause complex impacts on the urban environment and human health, and it may bring more severe effects under heatwave (HW) conditions. In this paper, a holistic review is conducted to articulate the findings of the synergies between UHI and HW and corresponding mitigation measures proposed by the research community. It is worth pointing out that most studies show that urban areas are more vulnerable than rural areas during HWs, but the opposite is also observed in some studies. Changes in urban energy budget and major drivers are discussed and compared to explain such discrepancies. Recent studies also indicate that increasing albedo, vegetation fraction and irrigation can lower the urban temperature during HWs. Research gaps in this topic necessitate more studies concerning vulnerable cities in developing countries. Moreover, multidisciplinary studies considering factors such as UHI, HW, human comfort, pollution dispersion and the efficacy of mitigation measures should be conducted to provide more accurate and explicit guidance to urban planners and policymakers.

Urban heat island (UHI) in conjunction with heatwave (HW) leads to exacerbation of thermal stress in urban areas. Prior research on UHI and HW has predominantly concentrated on examining the thermal conditions at the surface and near-surface, with few investigations extending to the radiative and dynamical interactions of UHI and HW, particularly with a focus on the inhomogeneities across local climate zones (LCZs). Here, we analyse the temperature disparity between HW and non-HW conditions across LCZs in the Sydney area by quantifying the contributions of individual radiative and dynamical processes using the coupled surface-atmosphere climate feedback-response analysis method (CFRAM). Three moist HW events in 2017, 2019, and 2020 are simulated using the Weather Research and Forecasting (WRF) model coupled with the single-layer urban canopy model (SLUCM). It is found that the maximum surface and 900 hPa temperature difference between HW and non-HW days may reach up to 10 K, with the increased net solar radiation during HWs being comparable to the typical level of anthropogenic heat flux in urban areas. It is also found that the reduction of clouds, the presence of vapour, and the increase of sensible heat contribute to the warming effect to various degrees, with the contribution of clouds being the most dominant. Conversely, the generation of dry convection and the increase of latent heat flux lead to cooling effects, with the latter being more dominant and capable of causing up to 10 K surface temperature difference between LCZ1 (compact high-rise) and LCZ9 (sparsely built). The differences in the contributions of climate feedback processes across different LCZs become more evident during more severe and humid HWs. These findings underscore the necessity of implementing LCZ-tailored heat mitigation strategies.

The in-plane seismic performance has been studied by many researchers all over the world, whereas few studies have been done on the out-of-plane behavior of the infilled RC frames. In this paper, a separate finite element model for simulating the out-of-plane failure mode and capacity of masonry-infilled RC frames is developed using 3-D elements with damage-plasticity material model and the surface-based contact cohesive interaction model simulating the interface between blocks. Comparison between the results of analysis and experiment indicates that the present model can successfully simulate the out-of-plane behavior of the structure.

This study is concerned with the impact of urban expansion on urban heat during heat Waves (HWs). The City of Sydney is planning to expand its urban areas in the coming years to meet the increasing demand for housing and other needs, which may potentially alter the temperature in urban areas as well as the surrounding areas. This study is designed to evaluate the potential impact of urban expansion on the urban climate in the Sydney area. Three scenarios have been considered: 1) replacing the urban areas with forests, 2) using the current LCZs in urban areas, which includes different LCZ types, and 3) implementing all urban areas with high-density urban LCZ1 to investigate the maximum possible impact. Simulations are carried out by coupling the weather research and forecasting (WRF) model with the single-layer urban canopy model (SLUCM) during three HW events in 2017, 2019 and 2020. The Random Forest (RF) model is used to determine the importance of individual features. The results indicate that urbanization increases the temperature, especially the surface temperature, in both urban and surrounding rural areas, and the maximum temperature can reach up to 1 °C. The impact of urbanisation on urban climate is more substantial when the HW is more intense. The study also reveals that albedo consistently exhibits the highest importance scores, particularly during HW days, when its influence on surface temperature exceeds 0.6 in most cases.