As an ecological green building material, natural bamboo has many advantages such as a light weight, high strength, and short growth cycle. Natural bamboo is widely used in landscape architecture and fabricated structures. However, in bamboo building structures, the most common bolted joints often appear cleaved along the grain. In this paper, glass fiber-reinforced polymer (GFRP) is designed to wrap and improve the shear capacity of natural bamboo-bolt composite joints. According to the corresponding material parameters, the finite element model of composite joints is established, and the key influencing variables of the bearing capacity, namely the bolt diameter, bamboo tube outer diameter, and screw end distance, are analyzed. In addition, according to the European analytical yield model of bolted connections, the analytical calculation method of the bearing capacity is proposed and compared with the experimental and simulated values. The results showed that the numerical model and the modified analytical model can suitably describe the bearing capacity of composite joints, and a higher bolt diameter, along with the bamboo outer diameter, will lead to a higher ultimate load of the composite joints. Moreover, the bearing capacity of composite joints has no obvious relationship with the end spacing.

To investigate an appropriate wind load design for buildings considering dynamic air density changes, classical extreme value and copula theories were utilized. Using wind speed, air temperature, and air pressure data from 123 meteorological stations in Shandong Province from 2004 to 2017, a joint probability distribution model was established for extreme wind speed and air density. The basic wind pressure was calculated for various conditional return periods. The results indicated that the Gumbel and Gaussian mixture model distributions performed well in extreme wind speed and air density fitting, respectively. The joint extreme wind speed and air density distribution exhibited a distinct bimodal pattern. The higher the wind speed was, the greater the air density for the same return conditional period. For the 10-year return period, the air density surpassed the standard air density, exceeding 1.30 kg/m³. The basic wind pressures under the different conditional return periods were more than 10% greater than those calculated from standard codes. Applying the air density based on the conditional return period in engineering design could enhance structural safety regionally.

As the capital of China and a densely populated major city, the characteristics of Beijing’s near-surface wind field change significantly with the increase in the density of underlying urban structures. The high randomness of natural wind makes it extremely difficult to develop a universally applicable wind-resistant load design code based on topographic factors and architectural features. This article takes the wind speeds recorded at 15 different height levels within the urban area by the 325 m meteorological tower in Beijing from 1991 to 2020 as the research subject. It quantifies the wind speed trends at different heights and introduces time-varying functions to establish a non-stationary wind speed model based on the optimal model. Additionally, it compares the basic wind speeds and wind pressure height variation coefficients obtained from measurements with the standards. The results show that, during the past 30 years of urbanization, the near-surface wind speed in the Beijing area has shown a decreasing trend. The model incorporating time-varying functions exhibited the best fit and demonstrated good predictive capabilities, with its calculated basic wind speeds being relatively high. The wind pressure height variation coefficient values in Beijing are between Class C and Class D terrains, being closer to Class C at lower altitudes. The conclusion reveals that urbanization has a significant impact on wind speeds, primarily concentrated at lower height levels, and that the basic wind speeds calculated based on standards underestimate the actual conditions when this impact is not considered. Although the average wind speed’s wind profile index across the entire time series is mostly greater than the fixed value of 0.3 given by Class D, this represents an overestimated wind profile index for maximum wind speeds.

In dealing with issues such as soil erosion and slope instability, plant roots enhance the shear strength of the soil mass through their anchoring effect. However, in nature, cyclic loads such as flash floods and blizzards indirectly impose fatigue effects on plant root systems. To explore the impact of cyclic loads on the anchoring capacity of plant roots, this paper selects the roots of Betula platyphylla as the research object and uses a monotonic load and cyclic load as two loading modes. Under different loading amplitudes (25%, 50%, and 75%), root diameters and burial depths (50 mm, 100 mm, and 150 mm), and soil moisture contents (11.85%, 13.85%, and 15.85%), the effects of each factor on the anchoring capacity of the roots under cyclic loading are analyzed. The results showed that the root–soil interface exhibited two failure modes under different cyclic load amplitudes, and the cyclic load significantly reduced the maximum friction of the root–soil interface. As the cyclic load amplitude increased (from 25% to 75%), the hysteretic curve envelope area increased, and the growth rate of cumulative residual slip changed from decreasing to decreasing and then increasing. A good correlation was found between cumulative residual slip and the number of loading cycles, and the three characteristic slips were correlated with loading amplitude but not significantly with diameter. The increase in soil moisture content, root embedment depth, and diameter led to an increase in the ratio of the two maximum friction forces. It was shown that a certain degree of plasticity exists at the root–soil interface to resist environmental stresses in nature. At high fatigue stress levels, the root–soil interface is more nonlinear, and as the load amplitude increases, more energy is dissipated, and bond damage between the root–soil interface becomes more pronounced. The root–soil interface gradually degraded under long-term cyclic loading, whereas the increase in root depth and soil water content could resist the negative effect of cyclic loading on anchorage capacity, and the resistance effect became more and more obvious with the increase in diameter.