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This paper summarises experimental investigations conducted on a novel connector assembly consisting of hollow steel tubes placed inside cross-laminated timber panels. The criteria that drove the connector development were: (i) easy to manufacture and install; (ii) high capacity, stiffness, and ductility; and (iii) neglectable damage to the timber. A total of 24 test assemblies with varying steel tube diameters (ranging from two to four inch) were tested using quasi-static monotonic and reversed cyclic loading. The results demonstrated that – when using an appropriate connection layout – the desired ductile steel yielding failure mechanism was initiated and wood crushing of any form was avoided. The tested configurations reached load-carrying capacities up to 58 kN, exhibited high stiffness (>15 kN/mm), and were classified as moderately to highly ductile. The research presented herein demonstrated that this novel connection assembly for cross-laminated timber panels can be utilized in seismic regions.

Tall mass-timber buildings utilize engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and more flexible than buildings made from concrete, masonry or even steel. In general, drift sensitive components of tall mass-timber buildings could be susceptible to damages due to increased deflection when subjected to extreme wind storms like violent tornadoes. This paper assessed the structural performance of a multi-story mass-timber building, which was designed using the customary 1-in-50 years design wind speed of the 2010 National Building Code of Canada with a load factor of 1.4, under experimentally simulated tornado-like wind fields. In the study, wind loads were obtained from laboratory simulations of tornado-like wind field and atmospheric boundary layer flow at Western University, Canada. Tornadic wind loads from the laboratory tests were scaled to five Enhanced Fujita wind speeds, representing various levels of damage. Dynamic structural analyses were carried out in time-domain to include the possible amplification due to the dynamic component of the excitation and assess floor level inter-story drift and shear force demands for various parameters. The varied parameters were tornado intensity level, the orientation of the building (aerodynamic direction), and critical damping ratio. Based on the obtained results, the vulnerability of drift sensitive components of the study building under tornado-like wind field was estimated. It is shown that strong tornadoes may pose significant damage to drift sensitive non-structural components of multi-story mass-timber buildings. Finally, roadmaps to improve the design of mass-timber buildings in tornado-prone areas are forwarded.

Industrial buildings often have irregularities due to operational and complex industrial process. In this paper, a thermal power plant with mass and vertical irregularities was designed with the 2010 ASCE and AISC design codes. Subsequently, a parametric study was undertaken on simplified braced frames to quantify the impact of mass and vertical irregularities, as well as their combined effect. Detailed numerical models were developed in Open System for Earthquake Engineering Simulation platform. With a high seismicity level in China, ground motions were selected and nonlinear time-history analyses were performed. Subsequently, probabilistic seismic demand models, seismic fragilities, and risks were developed for different performance levels. The results show that the vertical irregularity generated larger detrimental effect than mass irregularity, and need more attention in structural design. Collapse risk increased the most due to the combined effect of mass and vertical irregularities. Furthermore, under small earthquake intensities, the thermal power plant with the combined irregularities had higher risk in functional disruption.

This paper presents the results of shake table tests and periodical friction tests to evaluate the dynamic and long-term performance of a novel connector using a wood friction (friction-based connectors). The friction-based connectors are a quite simple system in which the wood is bolted transversely to generate friction force. The shake table tests showed that the type of hysteresis loop of the wall with the friction-based connectors exhibited a bilinear, and significantly reduced the maximum response displacement even when the conventional walls were combined. In addition, more than 60% of the total energy was absorbed by the wall with friction-based connectors, even the load bearing ratio of the wall was about 30%. The periodical friction tests of the connectors and the wall with the friction-based connectors indicated that the friction forces were mostly linked to the relaxation behavior of wood, and although the friction forces were significantly affected by humidity fluctuations, long-term friction forces were expected to be maintained.

Reinforced concrete frames with unreinforced masonry infill walls represent a widely adopted building system. During seismic events, infill walls, usually considered as non-structural elements, may significantly affect the characteristics of the system in terms of in-plane stiffness, strength, and energy dissipation capacity. The assessment of framed structures infilled with unreinforced masonry walls has been investigated since the 1950s. Developing reliable numerical models of infill walls has become an important issue since then. The analytical simplified model based on equivalent diagonal struts is often used to assess the infilled frames response. The nonlinear behavior of the equivalent diagonal strut is usually described by constitutive laws that account for the stiffness, the strength and the hardening or softening behavior of the infill. The present work focuses on the evaluation of various parameters needed to define the monotonic and hysteretic response of infill walls modelled by equivalent struts. In order to select a simple and reliable analytical model that suitable for representing the infill wall response, different strut formulations and hysteretic models have been analysed in detail and used to reproduce several experimental tests available in the literature. The numerical analyses are performed by means of the OpenSees computer program. Three uniaxial material models available in OpenSees are used to assess their capability in reproducing the experimental hysteretic response. Finally, from the comparison among different models and between numerical and experimental results, suggestions are made to properly model the in-plane non-linear response of infills.

Outriggers have been proven to be an efficient system to reduce the dynamic responses of core-tube type high-rise buildings by utilizing the axial stiffness of the peripheral columns. However, outer columns and outriggers are subjected to excessive lateral force demands. To reduce the demand, the damped outrigger is used where dampers are installed between the perimeter columns and outriggers. To improve the performance and enhance the residual deformation, in this paper, the use of shape memory alloy (SMA) springs is introduced to dissipate energy. The SMA dissipates energy through a hysteretic phase transformation of its microstructure triggered by cyclic loading. In the mathematical model implementation, the nonlinear behavior of superelastic SMA is linearized by the stochastic equivalent linearization method. Stochastic uncertainty in the ground motion is considered, and the performance is assessed by minimizing the failure probability of the structure. To solve the optimization problem, Kriging is used as a surrogate model. For better accuracy of the surrogate model, an efficient global optimization scheme is used. The purpose of the optimization adopted in this study is to find optimal design parameters associated with the initial stiffness of the SMA and the location of the outrigger. The results clearly demonstrated the efficacy of the proposed SMA based outrigger.

Tie spacing, concrete and steel properties, amount of reinforcement and column height are factors (or parameters) that can affect the performance of bridge piers under lateral loads. These parameters differ significantly from older bridges to modern bridges. Here, a detailed parametric study has been performed to understand the effects of these factors and their interactions on limit states of bridge columns using factorial analysis. Fiber modeling approach has been implemented to determine the performance of bridge piers (such as cracking base shear, cracking displacement, yield base shear, yield displacement, crushing base shear/shear capacity, displacement at crushing/shear failure and ductility) under lateral loads. This study shows that simple predictive equations can be derived from the parametric study, to estimate the cracking, crushing and yielding displacement of a bridge pier with reasonable accuracy.

The use of superelastic shape memory alloys (SMAs) as a reinforcing material in concrete structures is gradually gaining interest among researchers. Because of SMAs’ different mechanical properties compared to regular steel, use of SMA as reinforcement in concrete may change responses of structures under seismic loads. In this study, the effect of SMA as reinforcement in concrete structures is analytically investigated for three different storeys (3, 6 and 8) reinforced concrete (RC) buildings. For each building, three different reinforcement detailing are considered: (i) steel reinforcement (Steel) only, (ii) SMA rebar used in the plastic hinge region of the beams and steel rebar in other regions (Steel-SMA), and (iii), beams fully reinforced with SMA rebar (SMA) and steel rebar in other regions. For each case, columns were reinforced with steel rebar. Nonlinear static pushover analyses were performed to determine the overstrength and ductility of Steel, Steel-SMA and SMA RC buildings. Furthermore, nonlinear dynamic time history analyses were also performed using an ensemble of ten earthquake records to determine the seismic demand and capacity ratio in terms of base shear and drift for each type of RC building. Results obtained from the analyses confirm the seismic performance of low and medium rise frames while utilizing SMA as reinforcement.