According to piloti design, the outdoor thermal environment can be improved in cities with hot summer conditions. Taking Chinese cities with a hot summer and cold winter as the research object, this ...paper discusses the improvement of the outdoor thermal environment of residential districts in summer by considering piloti design factors. In this article, according to our investigation of piloti design in Wuhan, a basic model of the overhead layer in the Wuhan residential area is presented, along with the effects of different piloti ratios (0–80%), piloti heights (2–6 m), and greening rates (30–35%) on the outdoor thermal environment of buildings. The average air temperature and average wind speed at the pedestrian level are used as outdoor thermal environment indicators, the average PET is used as the outdoor thermal comfort indicator, and the comfort wind ratio is used as the outdoor wind comfort indicator. The results show that increasing the ratio of corridor columns has the greatest thermal comfort enhancement effect in the corridor area, and when the piloti ratio increases from 20% to 80%, the PET in piloti areas reduces by 2.926 °C. Improving the greening rate has the greatest thermal comfort enhancement effect in the passageway area, and when the greening rate increases from 20% to 80%, the PET in piloti areas reduces by 0.9 °C. Furthermore, the increases in both the piloti ratio and piloti height have an enhancement effect on the outdoor wind environment and wind comfort, with thresholds of a piloti ratio over 60% and a piloti height over 5 m. In contrast, the increase in the greening rate will deteriorate the outdoor wind environment and wind comfort. The conclusions of this study are of great significance for the planning and design of overhead layers in residential areas in hot and humid areas in summer.
This paper studies the influence of different piloti rates (0%, 20%, 40%, 60%, 80%, 100%) on outdoor wind comfort for three building groups, i.e., determinant type, point type, and enclosure type. ...LES (Large Eddy Simulation) is used to simulate the wind environment of three clusters at six different piloti rates. This paper mainly studies the effect of piloti rate on wind speed at pedestrian level (1.5 m). The outdoor wind environment was analyzed using the average wind speed ratio, and outdoor wind comfort was evaluated using the comfortable wind ratio. The following results were obtained: (1) The piloti setting has little influence on the overall wind speed in the target area, and even an inappropriate piloti rate setting may reduce the overall average wind speed in the target area. (2) A comprehensive comparison of the three building layouts shows that the comfortable wind ratio of the determinant layout is the highest when the piloti ratio is 80%. The results of this study can provide architects and urban planners with reference for piloti and urban layout settings.
The problem of inappropriate time-history waveforms due to gaps between wall and fluid particles in the boundary conditions of SPH method was solved by modeling the wall particles shifted by the ...smoothing length. Based on the verified method, a fluid analysis was performed where cubic buildings were aligned. As a result, the continuity of pilotis space in orthogonal direction to mainstream causes the concentration of the hydraulic force on the wall of the building located downstream direction of the piloti-type buildings. And the continuity of pilotis space in mainstream direction also keeps the level of water pressure over a distance.
The present study describes the structural performance of a soft-first-story column-beam joint with mechanical anchorage of column longitudinal rebar. A new strengthening method using the anchorage ...reinforcement is presented to prevent brittle anchorage failure in this type of structure. A series of static loading tests was conducted using two scaled models representing the above column-beam joint to verify the effectiveness of the proposed strengthening. The test results clarified that the structural performance of the joint specimen was significantly improved by arranging the anchorage reinforcement.
There has been an insufficient study of passive climate adaptability that considers both the summer and winter season for the outdoor thermal environment of hot-summer and cold-winter cities. In this ...study, we performed a quantitative simulation to research the passive climate adaptability of a residential area, considering piloti as the main method for climate adaptation in a hot-summer and cold-winter city in China. Numerical simulations were performed with a coupled simulation method of convection, radiation, and conduction. A cubic non-linear k⁻ε model proposed by Craft et al. was selected as the turbulence model and three-dimensional multi-reflections of shortwave and longwave radiations were considered in the radiation simulation. Through the simulation, we found that setting the piloti at the two ends of the building was the optimal piloti arrangement for climate adaptation. Then the relationship between the piloti ratio (0%, 20%, 40%, 60%, and 80%) and the outdoor thermal environment was studied. It could be concluded that with the increasing piloti ratio, the wind velocity increased, the mean radiant temperature (MRT) decreased slightly, and the average standard effective temperature (SET*) decreased to 3.6 °C in summer, while in winter, with the increasing piloti ratio, the wind velocity, MRT, and SET* changed slightly. The wind environment significantly affected the SET* value, and the piloti ratio should be between 12% and 38% to avoid wind-induced discomfort.
There are multiple initiatives aimed at strengthening coastal communities against tsunami disaster risks, such as growing vegetation belts, construction of embankments, moats, and different hybrid ...alternatives. To find a solution for strengthening the coastal buildings themselves, we firstly reviewed the flow phenomena around a single emergent (circular and rectangular) cylinder (case C1), which was considered as a piloti-type column under different Froude conditions, and evaluated the formation of surface bow-waves, hydraulic jump detachment, and wall-jet-like bow-waves. Secondly, the flow characteristics were investigated under the same Froude conditions with side-by-side two-cylinder (case C2) and four-cylinder (case C4) arrays in an open channel. Surface bow-wave length (LBw) increased by 7–12% over the rectangular cylinders (RCs) compared to the circular cylinders (CCs) with a subcritical flow. For the supercritical flow with a 1/200 bed slope, hydraulic jump detachment was observed in relation to the Froude number. The observed length of the hydraulic jump detachment (Ljump) varied between 3.1–8.5% and 4.2–12.9% for the CCs and RCs in the supercritical flow with a 1/200 bed slope. In addition, the wall-jet-like bow-wave height (hjet) over the CCs was increased by 37% and 29% compared to the RCs with a supercritical flow and zero bed slope (orifice-type flow). For case C4, a hydraulic jump was observed for the supercritical flow over the horizontal channel bed. Finally, empirical equations were defined concerning the geometrical shape and arrangement based on the experiment data for the single and side-by-side configurations of the cylinders to validate the height of the wall-jet-like bow-wave as the most critical flow property.
This study evaluated the influence of additional shear walls, constructed on the first floor, as strengthening methods for a piloti-type building subjected to earthquake loadings. Piloti-type ...buildings are commonly designed as urban structures in many cities of South Korea. The existence of just columns on the first floor of the building is a feature that is advantageous from an architectural viewpoint, and yet has potential structural disadvantages. Such columns usually exhibit shear–axial failure, due to inherent vertical and horizontal irregularities and insufficient seismic reinforcements. Among several retrofitting methods, including additional braces, carbon fiber reinforced polymers, dampers, and so forth, this research considered reinforced concrete shear walls to improve the seismic responses of piloti buildings. A parametric analysis of the location of the retrofitted shear walls in a typical piloti building was implemented using the Zeus-NL program. Nonlinear time history analysis and incremental dynamic analysis were performed to comparatively evaluate the structure’s seismic responses and fragility curves before and after retrofit.
A series of tsunami water tank experiments have been conducted to study global and local tsunami actions on low-to-mid-rise buildings with or without openings and piloti space. Each small-scaled ...experimental model produced by 3D printer is assumed as a three-story building of square plan with four corner columns and a center core. Wave pressures generated on several portions of external and internal walls are measured to discuss the local tsunami action, whereas wave forces acting on the whole building are measured to discuss the global tsunami action. Numerical analyses have been carried out to simulate the flow of tsunami inside and outside of the buildings and its effect on building structures through the comparison with experimental results. Based on experimental and analytical results, conclusions within this study are summarized as follows: 1) The existence of piloti space reduces the rise of water level and run-up on the front wall. 2) Breaking of glass windows causes the decrease in wave pressure on the external wall and the increase in wave pressure on the internal core wall. 3) Non-fragile windows cause the increase in water level and run-up at the front surface and consequently the rise of water pressure. 4) Maximum wave pressure tends to be generated on the internal core wall rather than on the external wall. 5) Tsunami flowing into the inside of building drains out of side and rear walls depending on flow velocity. 6) Horizontal wave force acting on the whole building decreases by 20 to 35% in the case with openings and piloti space compared to the case without openings and piloti space. 7) The core wall should be taken into consideration as a part of projected area in addition to exterior walls to evaluate horizontal wave force. 8) Vertical force acts downwardly in the case with openings and piloti space, although it acts upwardly in the case without openings and piloti space. 9) Tsunami simulation analysis based on VOF method is effective to evaluate both local wave pressure and global wave force. 10) The spatial distribution and time variation of wave pressure acting on the building and flow velocity inside and outside of the building can be accurately evaluated by tsunami simulation analysis. 11) Vertical force can be reasonably evaluated by slightly floating the building portion from the water bed in the analytical model.
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