Prefabricated construction has been widely accepted as an alternative to conventional cast-in-situ construction, given its improved performance. However, prefabricated concrete building projects frequently encounter significant delays. It is, therefore, crucial to identify key factors affecting schedule and explore strategies to minimise the schedule delays for prefabricated concrete building projects. This paper adopts the decision-making trial and evaluation laboratory (DEMATEL) model and analytic network process (ANP) method to quantify the cause-and-effect relationships and prioritise the key delay factors in terms of their importance in the Chinese construction industry. The DEMATEL model evaluates the extent to which each factor impacts other factors. The quantified extents are then converted into a prioritisation matrix through ANP. The delay factors of prefabricated construction projects are selected and categorised based on a literature review and an expert interview. Questionnaires are then implemented to collect the data. The results reveal that the issue of inefficient structural connections for prefabricated components is found to be the most significant factor and most easily affected by other delay factors. This research also suggests prioritising major delay factors, such as ‘lack of communication among participants’ and ‘low productivity’, in the Chinese construction industry during scheduling control. Overall, this research contributes an assessment framework for decision making in the scheduling management of prefabricated construction.

This paper presents the dynamic analytical solution of a piezoelectric stack utilized in an actuator and a generator based on the linear piezo-elasticity theory. The solutions for two different kinds of piezoelectric stacks under external load were obtained using the displacement method. The effects of load frequency and load amplitude on the dynamic characteristics of the stacks were discussed. The analytical solutions were validated using the available experimental results in special cases. The proposed model is able not only to predict the output properties of the devices, but also to reflect the inner electrical and mechanical components, which is helpful for designing piezoelectric actuators and generators in a comprehensive manner.

A type of radially layered cymbal piezoelectric energy harvester is designed and fabricated. It is made of two cymbal metal caps, two axially polarized piezoceramic rings, one solid metal disk, one common metal ring and one drilled metal ring. The mechanical couplings in radial direction are finished by using extra strong epoxy. The mechanical couplings in axial direction are finished by using screw bolts. Subsequently, the force transferring coefficient of each cymbal metal cap is approximated through both theoretical calculation and experimental calibration. Aiming at matching the road traffic induced vibration frequencies that are predominantly ranging from 5Hz to 25Hz, the approximated analytical model of the harvester is established at frequencies below 30Hz. The model’s predictions agree reasonably with the measured data. Furthermore, the experimental results indicated that the harvester was able to generate a power of about 0.92mW across a 0.8MΩ resistor under the force of 500N at a frequency of 20Hz. The present work provides a new design concept for developing the novel cymbal harvesters used in roadway systems to harvest the traffic induced vibration energy.

Periodic foundations for seismic isolation are getting increasing attention in the field of civil engineering. Initial stresses due to the vertical loads from the upper structures exist in periodic foundations. In the present paper, attenuation zones of two-dimensional periodic foundations including the effect of vertical loads are studied by the weak form quadrature element method. Comparisons with existing results in special cases without the effect of vertical loads are conducted to validate the proposed method, and good agreement is found. A comprehensive parametric study is conducted to investigate the effects of vertical loads on the attenuation zones. Moreover, frequency-domain and time-domain response analyses of a two-dimensional periodic foundation with finite unit cells are conducted to verify the theoretical results. The results show that bound frequencies of the attenuation zones, corresponding to the vibration mode of the core, are affected by vertical loads. It is also found that vertical loads shift the complete attenuation zones to lower frequencies and reduce the attenuation coefficients in the attenuation zones.

With the continuous increase in urbanization and population density, the prevalence of super high-rise buildings is rapidly growing. To ensure occupants' safety, especially during emergencies such as fires and earthquakes, it is essential to establish effective evacuation planning and guidance systems. Unfortunately, there is currently a lack of efficient solutions specifically designed to guide the evacuation of personnel in super high-rise buildings during fire incidents. This study develops a dynamic evacuation guidance system that utilizes the Dijkstra's algorithm and A* algorithm. By considering the unique characteristics of super high-rise buildings, the system aims to provide efficient and secure evacuation path selections. Furthermore, it dynamically guides occupants to avoid areas at high risk of fire, thereby preventing crowd congestion accidents. This study seeks to bridge the existing gap by presenting a relatively efficient solution for guiding the evacuation of personnel in super high-rise buildings during fire incidents.