Seismic Reliability Assessment of Inelastic SDOF Systems Subjected to Near-Fault Ground Motions Considering Pulse Occurrence

The ground motions in the orientation corresponding to the strongest pulse energy impose more serious demand on structures than that of ordinary ground motions.Moreover,not all near-fault ground motion records present distinct pulses in the velocity time histories.In this paper,the parameterized stochastic model of near-fault ground motion with the strongest energy and pulse occurrence probability is suggested,and the Monte Carlo simulation(MSC)and subset simulation are utilized to calculate the first excursion probability of inelastic single-degree-of-freedom(SDOF)systems subjected to these types of near-fault ground motion models,respectively.Firstly,the influences of variation of stochastic pulse model parameters on structural dynamic reliability with different fundamental periods are explored.It is demonstrated that the variation of pulse period,peak ground velocity and pulse waveform number have significant effects on structural reliability and should not be ignored in reliability analysis.Then,subset simulation is verified to be unbiased and more efficient for computing small reliable probabilities of structures compared to MCS.Finally,the reliable probabilities of the SDOF systems with different fundamental periods subjected to impulsive,non-pulse ground motions and the ground motions with pulse occurrence probability are performed,separately.It is indicated that the ground motion model with the pulse occurrence probability can give a rational estimate on structural reliability.The impulsive and ordinary ground motion models may overestimate and underestimate the reliability of structures with fundamental period much less than the mean pulse period of earthquake ground motions.

Dynamic changes of nutrient content in herbaceous peony seed

Herbaceous peony is a promising oilseed crop.‘Hangshao’and‘Fenghuang Niepan’are two cultivars with high yield and oil content In this study,seed reserved nutrient of these two genotypes were investigated during seed development process.Results showed that‘Hangshao’and‘Fenghuang Niepan’matured approximately 85 d after flowering(DAF).The development p rocess could be divided into four stages:seed formation and enlargement stage(S1),seed inclusion and enrichment stage(S2),crude fat rapid accumulation stage(S3)and dehydration and color transition stage(S4).During this process,100-seed fresh weight(HFW)and 100-seed dry weight(HDW)increased,whereas water content(WC)decreased.HFW,HDW and WC for‘Hangshao’seed at 85 DAF were28.56 g,20.78 g and 37.50%respectively,whereas those for‘Fenghuang Niepan’seed were 27.2 g,19.78 g,and30.85%respectively.In terms of the primary metabolites measuring,soluble protein content was consistently low(only 2.24%-3.15%),while starch content was relatively high(5.60%-24.81%).They displayed a trend of gradual increasing in early stage,followed by rapid decline.Crude fat tended to accumulate continuously with a linear upward trend starting at 40 DAF,and its maximum level was reached at 85 DAF(27.57%for‘Hangshao’and29.57%for‘Fenghuang Niepan’).For the secondary metabolites determination,total phenols content was relatively steady,maintaining at 107.7-129.9 mg/g for both cultivars,while total flavonoids content varied within25.33-65.33 mg/g for‘Hangshao’and 24.33-52.37 mg/g for Tenghuang Niepan’.The maximum level for both cultivars occurred at 55 DAF.Furthermore,crude fat content was found to be highly correlated with WC by correlation analysis and linear regression model definition(P≤0.01 and r=0.954).Thus,WC was recommended for evaluating crude fat in peony seed.These findings could provide scientific reference for high-yielding production practice for oleaginous peony plant.