Influence Of HF2V Damping Devices On The Performance Of The SAC3 Building Subjected To The SAC Ground Motion Suites

Recent advances in energy dissipation for structural systems can create structural connections that undergo zero sacrificial energy absorbing damage, even at extreme story drifts. However, questions exist around the ability of such structures to re-center after a major event. In this paper, the seismic performance of the as-designed SAC LA3 seismic frame with rigid moment connections at the beam ends is compared with the same frame using semi-rigid connections with high force-to-volume (HF2V) lead dissipators. Non-linear dynamic analysis is preformed using Abaqus™. With respect to re-centering, the presence of the gravity frames in the model is also considered. It was found that the placement of dissipators, ignoring the effect of gravity frames, caused a 12% increase in period due to the decreased stiffness of the connections. During design level ground shaking the semi-rigid connections with HF2V dissipators have slightly lower accelerations, up to an 80% increase in peak drift, and a 200% increase in the permanent displacement compared to the as-designed case, but no structural damage is expected. When gravity frames are considered, the floor accelerations decrease further, the peak displacements do not significantly change, but the residual storey drift ratios reduce to approximately 0.17%. This result is less than one half that of the as-designed frame, where typically gravity frame effects are not considered. The addition of braces with a stiffness 20% of the pushover stiffness ensures that the structures can re-center after any given event to within construction error. The realistic non-linear dynamic analyses combining HF2V lead dissipators with gravity frames and well-designed non-structural elements creates a system with almost no structural damage and low residual displacements

Analytical Investigation of the Effects of HF2V Damping Devices on the Seismic Performance of the SAC LA3 Building

In this paper, the seismic performance of a 3 storey seismic frame with rigid moment connections at the beam ends (commonly known as the SAC LA3 building) is compared with that of the same frame using semi-rigid connections with high force to volume (HF2V) lead dissipators. The presence of the gravity frames in the model is also considered. It was found that the use of semi-rigid connections with HF2V dissipators, ignoring the effect of the gravity frames, caused a 12% increase in period of the frame due to the decreased stiffness of the connections. Accelerations were slightly lower and there was up to an 80% increase in peak drift, and a 200% increase in the permanent displacement compared to the as-designed case, but no structural damage was expected. When gravity frames were considered, the floor accelerations decreased further, the peak displacements do not significantly change, but the residual storey drift ratios reduced to approximately 0.17%. This result is less than one half that of the as-designed frame, where typically gravity frame effects are not considered. The analyses show that combining HF2V lead dissipators with gravity frames and well-designed non-structural elements creates a system with almost no structural damage and low residual displacements

Influence Of HF2V Damping Devices On The Performance Of The SAC3 Building Subjected To The SAC Ground Motion Suites

Recent advances in energy dissipation for structural systems can create structural connections that undergo zero sacrificial energy absorbing damage, even at extreme story drifts. However, questions exist around the ability of such structures to re-center after a major event. In this paper, the seismic performance of the as-designed SAC LA3 seismic frame with rigid moment connections at the beam ends is compared with the same frame using semi-rigid connections with high force-to-volume (HF2V) lead dissipators. Non-linear dynamic analysis is preformed using Abaqus™. With respect to re-centering, the presence of the gravity frames in the model is also considered. It was found that the placement of dissipators, ignoring the effect of gravity frames, caused a 12% increase in period due to the decreased stiffness of the connections. During design level ground shaking the semi-rigid connections with HF2V dissipators have slightly lower accelerations, up to an 80% increase in peak drift, and a 200% increase in the permanent displacement compared to the as-designed case, but no structural damage is expected. When gravity frames are considered, the floor accelerations decrease further, the peak displacements do not significantly change, but the residual storey drift ratios reduce to approximately 0.17%. This result is less than one half that of the as-designed frame, where typically gravity frame effects are not considered. The addition of braces with a stiffness 20% of the pushover stiffness ensures that the structures can re-center after any given event to within construction error. The realistic non-linear dynamic analyses combining HF2V dissipators with gravity frames and well-designed non-structural elements creates a system with almost no structural damage and low residual displacements

HF2V dissipator effects on the performance of a 3 story moment frame

In this paper, the seismic performance of the as-designed SAC Los Angeles 3 storey seismic frame with rigid moment connections at the beam ends is compared with that of the same frame using semirigid connections with high force-to-volume (HF2V) lead dissipators. The presence of the gravity frames in the model is also considered. It was found that the placement of dissipators, ignoring the effect of the gravity frames, caused a 12% increase in period of the frame due to the decreased stiffness of the connections. During design level ground shaking the semi-rigid connections with HF2V dissipators have slightly lower accelerations, up to an 80% increase in peak drift, and a 200% increase in the permanent displacement compared to the as-designed case, but no structural damage is expected. When the gravity frames are considered, the floor accelerations decrease further, the peak displacements do not significantly change, but the residual storey dirft ratios reduce to approximately 0.17%. This result is less than one half that of the as-designed frame, where typically gravity frame effects are not considered. The realistic analyses combining HF2V lead dissipators with gravity frames and well-designed non-structural elements creates a system with almost no structural damage and low residual displacements

Analytical Investigation of the Effects of HF2V Damping Devices on the Seismic Performance of the SAC3 Building

In this paper, the seismic performance of the 3 storey seismic frame with rigid moment connections at the beam ends (commonly known as the SAC3 building) is compared with that of the same frame using semi-rigid connections with high force to volume (HF2V) lead dissipators. The presence of the gravity frames in the model is also considered. It was found that the placement of dissipators, ignoring the effect of the gravity frames, caused a 12% increase in period of the frame due to the decreased stiffness of the connections. During design level ground shaking the semi-rigid connections with HF2V dissipators have slightly lower accelerations, up to an 80% increase in peak drift, and a 200% increase in the permanent displacement compared to the as-designed case, but no structural damage is expected. When the gravity frames are considered, the floor accelerations decrease further, the peak displacements do not significantly change, but the residual storey dirft ratios reduce to approximately 0.17%. This result is less than one half that of the as-designed frame, where typically gravity frame effects are not considered. The analyses show that combining HF2V lead dissipators with gravity frames and well-designed non-structural elements creates a system with almost no structural damage and low residual displacements

Endogenous rhythmic growth, a trait suitable for the study of interplays between multitrophic interactions and tree development

As long-lived organisms, trees use resources to support both growth and below- and aboveground trophic interactions. Resources fluctuate in relation to periods of growth cease that are regulated by internal and external factors, and these fluctuations feed backs to trophic partners. Some major forest trees display an endogenous growth rhythm, and related pulses of variation in allocation of resources have been detected. As this trait makes it possible to separate growth into defined phases, it offers an opportunity to disentangle the intermingled complex regulation of growth and multitrophic interactions in trees. We present “TrophinOak”, a platform using microcuttings of pedunculated oak, a tree that displays endogenous rhythmic growth characterized by alternating shoot and root growth flushes. We select seven beneficial or detrimental above- and belowground partners including animals (Lymantria dispar, Pratylenchus penetrans, Protaphorura armata), fungi (Piloderma croceum, Microsphaera alphitoides, Phytophthora quercina) and bacteria (Streptomyces sp.), to synthesize bi- and tripartite trophic interactions, including ectomycorrhizal symbioses, and monitor fluctuations of carbon and nitrogen allocation as well as plant gene expression at distinct phases of oak growth. We use this model to identify and resolve the experimental challenges inherent in synthesizing diverse types of associations in a common microcosm system, in labeling plants with stable N and C isotopes and in analyzing transcripts in a non-model plant, a process which requires generating a specific contig library. We develop hypotheses and experimental design to test them in order to identify core mechanisms that help trees to modulate their own development and their multitrophic interactions for optimizing their long term performance in their environment. First results constitute a proof of concept that the platform works and enables us to test the hypotheses