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.

Pengaruh Penggunaan Base Isolation High Damping Rubber Bearing Pada Struktur Beton Bertulang

Salah satu cara yang dapat dilakukan adalah menggunakan peredam beban gempa dengan sistem isolasi dasar (base isolation system). Penggunaan base isolation system pada bangunan dapat mengisolasi perambatan getaran akibat gempa dari tanah ke struktur atas bangunan menggunakan komponen berbahan karet. Tujuan penelitian ini adalah untuk menganalisis pengaruh penggunaan sistem isolasi dasar berupa High Damping Rubber Bearing pada periode dan gaya geser dasar struktur beton bertulang. Objek penelitian adalah bangunan hotel 15 lantai dengan ketinggian 62,9 m. Penelitian diawali dengan pemodelan struktur menggunakan aplikasi ETABS v2016 sehingga didapatkan periode dan gaya geser dasar struktur fixbase. Tahap selanjutnya memberikan gaya pada model struktur dengan isolasi dasar High Dumper Rubber Bearing sehingga didapatkan periode dan gaya geser dasar struktur dengan base isolator. Hasil analisis pada struktur fixbase didapatkan periode sebesar 4,212 detik, dengan gaya geser dasar didapatkan sebesar 1470,725 ton. Sedangkan hasil analisis pada struktur dengan base isolator didapatkan periode sebesar 5,500 detik, dengan gaya geser dasar didapatkan sebesar 1286,071 ton. Maka dapat disimpulkan bahwa pada struktur dengan base isolator terjadi peningkatan periode sebesar 30,58 %, sedangkan gaya geser dasar terjadi penurunan 12,56 %.

Research on Longitudinal Collapse Mode and Control of the Continuous Bridge under Strong Seismic Excitations

Bridge collapse events are common in major earthquakes around the world, among which continuous girder bridges are the most involved. In order to explore the collapse mechanism of a continuous girder bridge in an earthquake, the collapse mode of a two-span continuous girder bridge specimen which had been studied by the shaking table test was analyzed. Then, on the basis of the conventional plate rubber bearing system, the collapse control strategies which were high damping rubber bearing, fluid viscous damper, lock-up clutch control methods were discussed. It is found that high damping rubber bearing can delay the collapse time but the collapse mode remains the same; lock-up clutch has the best displacement control effect for the superstructure, but its energy consumption performance is not as good as that of a fluid viscous damper; high damping rubber bearing is quite suitable for protecting the substructure under short-period ground motion to avoid the bridge collapse caused by the failure of piers; fluid viscous damper and lock-up clutch are suitable for protecting the superstructure under long ground seismic motion to avoid the bridge non-use resulted from girder lowering; three collapse control methods can improve the anti-collapse ability of the bridge specimen, although no matter which control method is used, the bridge specimen may still collapse under strong earthquakes, but the target of postponing collapse time can be realized by means of various effective control methods.