Work

Effect of NCO content on working principle and structural behavior of laminated polyurethane seismic bearings

Year: 2025

Type: article

Abstract: With the increasing constraints on urban development spaces and the rapid rise in traffic flow, there is a growing demand for urban overpasses and elevated bridges that utilize less land while exhibiting superior performance. Laminated polyurethane seismic isolation bearings (LPEB) have been widely adopted due to its high load bearing capacity. However, the isocyanate (NCO) content of polyurethane elastomer (PUE) materials has a serious effect on the mechanical properties and fatigue life of LPEB. In this study, PUEs with Shore hardness values exceeding 80 HA were synthesized by varying the NCO content from 8.4 % to 9.2 %, achieving tensile stresses ranging from 22.89 to 52.41 MPa and elongation at break between 358.01 % and 530.71 %. Notably, the PUE demonstrated high vertical stiffness and deformation resistance under 25 MPa compressive stress. Micromechanical analysis revealed that increasing NCO content to 9.2 % enhanced hardness and stiffness but reduced damping properties and low-temperature flexibility, accompanied by an elevated glass transition temperature. Conversely, the load carrying capacity and susceptibility of PUEs with lower NCO content are affected under high stress loading. Therefore, three PUE samples with NCO contents of 8.6 %, 8.8 % and 9.0 % were fabricated into LPEB and tested for mechanical properties. Their seismic effectiveness and fatigue life were further analyzed using numerical simulations in Opensees, Abaqus, and FE-Safe. The result indicated that LPEB with 9.0 % NCO exhibits vertical stiffness, horizontal equivalent stiffness, and damping ratio that are 1.15, 1.23, and 0.88 times higher, respectively, than those of the LPEB-8.6 % NCO. Moreover, under identical ground vibration energy, the LPEB-9.0 % NCO reduced deformation displacement by 5.98–31.89 % and extended service life by 33.2–44.1 %. This study provides a reference for the application of LPEB with different NCO.

Source: Case Studies in Construction Materials

DOI: 10.1016/j.cscm.2025.e04704

Authors: Xiaotao Yu, Yong Yuan, Zhuowei Deng, Siqi Wang, Hongping Zhu

Institutions: Huazhong University of Science and Technology, Wuhan Institute of Technology

Language: English

Topic: Vibration Control and Rheological Fluids

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $2,660