Challenges in sustaining resilience in the coastal settlements of south-eastern Bangladesh: Achieving self-sustenance through architectural synthesis

The coastal settlements in Bangladesh experienced recurring tropical cyclones and tidal surges in recent history because of geographical influences and global climate change. Despite improved evacuation management and adequate cyclone shelters patronized by donors, lately resulting in a reduced mortality rate, the property and economic losses were still substantial due to vulnerability of the settlements. As the short-term adaptative approaches such as migrating to the closest cyclone shelters have failed to sustain resilience, comprehensive and inclusive mitigation planning should be implemented to achieve more resilience in the long term. The research aimed to revise the conventional culturally-void concept and propose a prolonged solution by planning a self-sustained model of the cyclone-resilient village for the south-western coastal communities of Bangladesh. Initially, it searched for the identification and analysis of socio-cultural, economic, and environmental challenges in sustaining community resilience and later synthesizing architectural interventions to achieve self-sustenance. The synthesis focused on reducing the vulnerability of the coastal communities by enhancing their preparedness, resistance, and recovery from the prolonged impacts of coastal disasters through designing structurally and environmentally resilient homesteads, defensive landscape plans, and socioeconomic-communal development. The ultimate proposal offers more flexibility in selecting homesteads according to suitable materials, affordability, and profession.

An approach to congestion analysis in crowd dynamics models

This paper presents a novel approach to quantitatively analyzing pedestrian congestion in evacuation management based on the Hughes and social force models. An accurate analysis of crowds plays an important role in illustrating their dynamics. However, the majority of the existing approaches to analyzing pedestrian congestion are qualitative. Few methods focus on the quantification of the interactions between crowds and individual pedestrians. According to the proposed approach, analytic tools derived from theoretical mechanics are applied to provide a multiscale representation of such interactions. In particular, we introduce movement constraints that illustrate the macroscopic and microscopic states of crowds. Furthermore, we consider pressure propagation and changes in the position of pedestrians during the evacuation process to improve the accuracy of the analysis. The generalized force caused by the varied density of pedestrians is applied to calculate the final congestion. Numerical simulations demonstrate the validity of the proposed approach.

Effects of Different Staircase Design Factors on Evacuation of Children from Kindergarten Buildings Analyzed via Agent-Based Simulation

Staircase design is critical to the evacuation of children. Through an agent-based simulation, this study focused on the relationship between staircase design factors and evacuation efficiency in a multi-story kindergarten. A quantitative study was conducted on three critical architectural design factors: stair flight width, positional relationship, and design pattern of the juncture between the staircase and the corridor. The findings were as follows. (1) When the stair flight width ranges from 0.7 to 1.0 m, an increase in this width can improve evacuation efficiency significantly; when the width ranges from 1.1 to 1.4 m, evacuation efficiency is improved continuously, but an increase in this width range has a diminishing effect on evacuation efficiency; when the width is greater than 1.7 m, a further increase has an adverse effect on evacuation efficiency, because such a staircase space allows overtaking behaviors. (2) Under the same stair flight width conditions, evacuation efficiency is higher when the staircase and corridor are perpendicular to each other than when they are parallel, because the natural steering angle of the children was preserved during their evacuation. (3) The cut corner and rounded corner designs between the staircase and corridor improved evacuation efficiency and alleviated the congestion at bottleneck positions; the evacuation efficiency continued to rise with an increase in the cutting angle. These findings are expected to provide a useful reference for the evacuation design of kindergarten buildings and for emergency evacuation management.