Rubber tree and cassava: Biological features, practical use, ethnocultural traditions

Aim. To make a review of Hevea and Manihot, two related plant genera that have been used by humans for a long time, to analyze their biological features, to give information on their use, to present the most interesting materials associated with them. Main part. A review of Hevea and Manihot, useful plants in the tropics and subtropics, is carried out. Their characteristics are given, biological features are considered, and data on the places of origin, on the regions where they are cultivated are considered. Information on their use by people is presented: Hevea as a rubber-bearing, cassava as a food product. Special attention is paid to the cytogenetic features of Hevea and Manihot, information about the ancient polyploid origin of these plants. Conclusion. From ancient to the present time, mankind has been using in everyday life many valuable species of subtropical and tropical plants, including Hevea and Manihot, which are an integral part of ethnocultural traditions.

Isolation design and numerical calculation of isolated rubber bearing in continuous beam bridge in high seismic intensity area

The stability of bridges in the face of earthquake hazards has always been the focus of construction engineering. At present, a large number of bridge construction has begun to use isolation rubber bearings to increase the seismic capacity of bridges. However, in the face of high-intensity earthquake disasters, the seismic performance of the bridge is gradually unable to meet, the main reason is the lack of relevant research on the seismic performance of the bridge in high seismic intensity area. Therefore, this study will explore the changes of the bridge in the face of high-strength earthquake, and try to use high damping rubber bearings for the isolation design of the bridge. By establishing the finite element model of continuous bridge combined with isolation rubber bearing, the numerical calculation of bridge element is carried out on this basis, and the isolation effect of isolation rubber bearing is analyzed. The results show that the compression resistance and shear resistance of the isolated rubber bearing are strong. Under the influence of different seismic waves, the maximum displacement of the bearing is 0.131 m and the maximum horizontal force is 389.6 kN, which are lower than the allowable value of the bridge, and the overall seismic performance of the bridge has been significantly improved, which can play a good theoretical support in the construction of continuous bridges in high seismic intensity areas.

Strength analysis and method research of a light truck powertrain mounting system

This paper presents an integral strength checking method to solve the problem that the step-by-step strength checking method cannot check the strength of metal parts in the rubber mounting system of light truck powertrain. By establishing an integral finite element model including powertrain and rubber mount system and considering the rubber bearing and force transfer mode, the motion coordination and overall analysis of mount system and powertrain are realized. The calculation results show that the proposed method can easily and accurately complete the strength check of metal parts of the mounting system, which provides a reference for the structural design of the mounting system.

An Experimental Study on the Mechanical Properties of a High Damping Rubber Bearing with Low Shape Factor

A high damping rubber bearing (HDRB) is widely utilized in base-isolation structures due to its good energy dissipation capacity and environmentally friendly properties; however, it is incapable of isolating the vertical vibration caused by earthquakes and subways effectively. Thick rubber bearings with a low shape factor have become one of the important vertical isolation forms. This paper provides an experimental comparative study on high damping rubber bearings with low shape factor (HDRB-LSF), thick lead–rubber bearings (TLRB), and lead–rubber bearings (LRB). The abilities of the bearing and energy dissipation of the above bearings are analyzed contrastively considering the influence of vertical pressure, loading frequency, shear strain, and pre-pressure. Firstly, the HDRB-LSF, TLRB, and LRB are designed according to the Chinese Code for seismic design of buildings. Secondly, cyclic vertical compression tests and horizontal shear tests, as well as their correlation tests, are conducted, respectively. The vibrational characteristics and hysteresis feature of these three bearings are critically compared. Thirdly, a corrected calculation of vertical stiffness for the thick rubber bearings is proposed based on the experimental data to provide a more accurate and realistic tool measuring the vertical mechanical properties of rubber bearings. The test results proved that the HDRB-LSF has the most advanced performance of the three bearings. For the fatigue property, the hysteresis curves of the HDRB-LSF along with TLRB are plump both horizontally and vertically, thus providing a good energy dissipation effect. Regarding vertical stiffness, results from different loading cases show that the designed HDRB-LSF possesses a better vertical isolation effect and preferable environmental protection than LRB, a larger bearing capacity, and, similarly, a more environmentally friendly property than TLRB. Hence, it can avoid the unfavorable resonance effect caused by vertical periodic coupling within the structure. All the experimental data find that the proposed corrected equation can calculate the vertical stiffness of bearings with a higher accuracy. This paper presents the results of an analytical, parametric study that aimed to further explore the low shape factor concepts of rubber bearings applied in three-dimensional isolation for building structures.

Analisis Pushover terhadap Variasi Penempatan High Damping Rubber Bearing (HDRB) pada Struktur Gedung Bertingkat

High Damping Rubber Bearing (HDRB) merupakan salah satu jenis isolator yang digunakan dalam perancangan struktur gedung tahan gempa, biasanya ditempatkan pada dasar bangunan dan berfungsi untuk meredam gaya gempa. Penelitian ini bertujuan untuk mengetahui respon struktur berupa gaya geser dasar dan simpangan antar lantai, serta tingkat kinerja struktur gedung bertingkat terhadap variasi penempatan HDRB menggunakan metode analisis pushover dengan bantuan software ETABS. Struktur gedung beton bertulang 12 lantai, dengan tinggi tiap lantai 4 m. Variasi penempatan HDRB pada model 1 di dasar gedung, pada model 2 di lantai pertama dan pada model 3 di tengah-tengah gedung. Standar analisis mengacu pada SNI 1726:2019 dan ATC-40. Hasil penelitian menunjukkan bahwa gaya geser dasar maksimum yang paling menentukan dari ketiga model struktur gedung bertingkat yang terbesar, yaitu 2.566,78 kN dengan perpindahan maksimum 0,35 m. Tingkat kinerja berdasarkan ATC-40 termasuk dalam kategori aman yaitu Immediate Occupancy (IO). Berdasarkan SNI 1726:2019 memenuhi batasan simpangan antar lantai izin.