Buildings

Tornadoes represent a significant natural hazard to critical infrastructure worldwide, as they can cause sudden and severe damage with far-reaching societal consequences. In this study, the authors investigate the vulnerability and resilience of public and critical infrastructure buildings in the Czech Republic to tornado impacts, with a particular focus on the 2021 South Moravian tornado. The research identifies key structural weaknesses, damage patterns, and protective factors through a detailed field survey of 46 tornado-affected buildings. The results highlight that building size, construction quality, material durability, and maintenance significantly influence tornado resistance. Buildings of reinforced concrete and steel frames showed higher resistance, while older, inadequately maintained masonry and timber buildings were highly susceptible to collapse. The conclusions recommend regular maintenance of building, structural reinforcement, installation of protection elements and robust roof system of public buildings. These insights provide a practical foundation for strengthening disaster preparedness policies at regional or national levels.

The lighting environment has transcended purely functional illumination and has evolved into a critical medium for orchestrating narrative rhythm and modulating audience emotional responses. However, existing studies often examine photometric properties and human emotional responses in isolation, failing to establish a quantitative coupling mechanism to elucidate the relationship between light distribution, visual attention, and emotional states. This study aims to quantify the coupling mechanisms between luminous environmental parameters (illuminance and CCT), visual attention distribution, and emotional states (PAD) in immersive narrative exhibition spaces for the optimization of visitor experience. Four screen-based simulated narrative scenes were constructed with different illumination levels (low/high) and four levels of correlated color temperature (2700 K, 3000 K, 4000 K, and 5000 K). Using the SIFT algorithm, the illuminance pseudo-color map and the eye-tracking heat map were spatially registered to quantify the spatial correlation between the physical light field and the visual attention field. The results demonstrate a significant nonlinear coupling effect: high-illuminance cold light (4000 K, 544 lx) establishes a strong guidance mechanism, with a high spatial correlation between visual attention and brightness ($r$ = 0.82), which significantly enhances physiological arousal and perceived dominance. Conversely, low-illuminance warm light (2700 K, 150 lx) leads to a weak coupling state ($r$ = 0.62), which promotes free visual exploration, thereby improving pleasure and perceived immersion. These results suggest that lighting design should not be treated as a fixed set of parameters, but rather as an adjustable strategy that responds to changes in visual attention and emotional experience. By modifying the strength of visual and optical interaction, lighting conditions can influence how visitors move from initial perception to emotional engagement. This provides practical support for applying evidence-based lighting strategies in the design of cultural heritage spaces.

After a shear-type strongly braced steel frame suffers from non-sway buckling, the effective length factor for columns in a non-sway frame should be selected for stability calculations, and the P-δ effect should be considered for second-order analysis. However, an unreasonable design may result if the shear-type bracing cannot be accurately and practically designed to meet the strong bracing requirements. In this paper, an analytical method for the critical bracing design of shear-type strongly braced steel frames is proposed. First, the relationship between the shear-type bracing stiffness and buckling load of structures is analyzed, and then the calculation formula for the story critical bracing stiffness is derived based on the critical bracing stiffness of the separation column. Furthermore, the relationship between the cross-sectional properties of the shear-type brace members and the critical bracing lateral stiffness is established. Based on this, a direct calculation formula for the critical brace area of shear-type strongly braced steel frames is derived. This formula can determine whether a shear-type braced steel frame will experience sidesway or non-sway buckling, thereby providing a basis for selecting the appropriate approach for calculating the column effective length factor and second-order effects.