Bottlenecks occur in a wide range of situations from pedestrians, ants, cattle, and traffic flow to the transport of granular materials. We examine granular flow across a bottleneck using simulations of monodisperse disks. Contrary to expectations but consistent with previous work, we find that the flow rate across a bottleneck actually increases if an obstacle is optimally placed before it. Using the hourglass theory and a velocity-density relation, we show that the peak flow rate corresponds to a transition from free flow to congested flow, similar to the phase transition in traffic flow.

Minkowski operators (dilation and erosion of sets in vector spaces) have been extensively used in computer graphics, image processing to analyze the structure of materials, and more recently in molecular dynamics. Here, we apply those mathematical concepts to extend the discrete element method to simulate granular materials with complex-shaped particles. The Voronoi-Minkowski diagrams are introduced to generate random packings of complex-shaped particles with tunable particle roundness. Contact forces and potentials are calculated in terms of distances instead of overlaps. By using the Verlet method to detect neighborhood, we achieve CPU times that grow linearly with the body's number of sides. Simulations of dissipative granular materials under shear demonstrate that the method maintains conservation of energy in accord with the first law of thermodynamics. A series of simulations for biaxial test, shear band formation, hysteretic behavior, and ratcheting show that the model can reproduce the main features of real granular-soil behavior.

Three-dimensional (3D) printing technologies are transforming the design and manufacture of components and products across many disciplines, but their application in the construction industry is still limited. Material deposition processes can achieve infinite geometries. They have advanced from rapid prototyping and model-scale markets to applications in the fabrication of functional products, large objects, and the construction of full-scale buildings. Many international projects have been realised in recent years, and the construction industry is beginning to make use of such dynamic technologies. Advantages of integrating 3D printing with house construction are significant. They include the capacity for mass customisation of designs and parameters to meet functional and aesthetic purposes, the reduction in construction waste from highly precise placement of materials, and the use of recycled waste products in layer deposition materials. With the ultimate goal of improving construction efficiency and decreasing building costs, the researchers applied Strand 7 Finite Element Analysis software to a numerical model designed for 3D printing a cement mix that incorporates the recycled waste product high-density polyethylene (HDPE). The result: construction of an arched, truss-like roof was found to be structurally feasible in the absence of steel reinforcements, and lab-sized prototypes were manufactured according to the numerical model with 3D printing technology. 3D printing technologies can now be customised to building construction. This paper discusses the applications, advantages, limitations, and future directions of this innovative and viable solution to affordable housing construction.

Pedestrian dynamic models are typically designed for comfortable walking or slightly congested conditions and typically use a single disk or combination of three disks for the shape of a pedestrian. Under crowd conditions, a more accurate pedestrian shape has advantages over the traditional single or three-disks model. We developed a method for simulating pedestrian dynamics in a large dense crowd of spheropolygons adapted to the cross section of the chest and arms of a pedestrian. Our numerical model calculates pedestrian motion from Newton's second law, taking into account viscoelastic contact forces, contact friction, and ground-reaction forces. Ground-reaction torque was taken to arise solely from the pedestrians' orientation toward their preferred destination. Simulations of counterflow pedestrians dynamics in corridors were used to gain insight into a tragic incident at the Madrid Arena pavilion in Spain, where five girls were crushed to death. The incident took place at a Halloween Celebration in 2012, in a long, densely crowded hallway used as entrance and exit at the same time. Our simulations reconstruct the mechanism of clogging in the hallway. The hypothetical case of a total evacuation order was also investigated. The results highlights the importance of the pedestrians' density and the effect of counterflow in the onset of avalanches and clogging and provides an estimation of the number of injuries based on a calculation of the contact-force network between the pedestrians.

To reduce the impact of climate change in the form of low-carbon developments, innovations in sustainable building strategies are imperative. In this regard, the performance of a double-roof house consisting of a photovoltaic panel roof (PV) and green roof (GR) was compared to traditional solar-roof buildings. The synergy between both the PV and GR systems was analysed by numerical simulations and physical modelling across the four seasons. The performance of the systems was assessed on three dimensions: indoor thermal comfort, photovoltaic temperature, and energy yield. The synergy of photovoltaic roofs with green roofs kept the indoor environment 6% more comfortable than solar roofs. The synergy also reduced the photovoltaic temperature by up to 8 °C, extending the PV life span and increasing the energy yield by 18%.

This paper presents a preliminary finite element model in Strand7 software to analyse creep and shrinkage effects on the prestressed concrete ribs of the Sydney Opera House as remarkable heritage. A linear static analysis was performed to investigate the instantaneous impacts of dead and wind loads on the complex concrete structure which was completed in 1973. A quasistatic analysis was performed to predict the effects of creep and shrinkage due to dead load on the structure in 2050 to discern its longevity. In 2050, the Sydney Opera House is expected to experience 0.090% element strain due to creep and shrinkage and therefore suffer prestress losses of 32.59 kN per strand. However, given that the current time after prestress loading is approximately 50 years, the majority of creep and shrinkage effects have already taken place with 0.088% strain and 32.12 kN of prestress losses. The analysis concludes that very minor structural impacts are expected over the next 30 years due to creep and shrinkage, suggesting a change in conservation focus from large structural concerns to inspection and maintenance of minor issues of surface cracking and water ingress. The analysis is the first step in the application of more complex finite element modelling of the structure with the integration of complex building information models. The main motivation to undertake the current numerical simulation is to determine a cost-effective solution when it comes to the long-term time-dependent analysis. The paper also will suggest future directions for monitoring unique historical buildings, including ‘digital twin’.