Current Design Values Research Articles

The angle of repose and base stress distribution of granular piles: An experimental investigation

The angle of repose and characteristics of the base stress distribution underneath granular piles serve as essential indicators in understanding the mechanical and packing properties of particle system. One counterintuitive phenomenon is that there is an evident dip of the base stress beneath the pile apex that might have implications in the design of granular pile facilities. The repose angle and stress dip are influenced by many categories of factors and exhibit different variations. Based on the localized source method, particle packing experiments were conducted to investigate the effects of funnel height, particle size, particle shape, and packing method on the repose angle and the vertical stress distribution of granular piles. The experimental results show that the repose angle of piles of irregular particle shape and higher funnel height is much larger, but there is a decreasing trend of repose angle with increasing particle sizes. The natural packing angles before and after the critical collapse of granular pile exhibits periodic variation. On the other hand, the stress dip phenomenon occurred in all granular piles constructed by localized procedure. An increase in funnel height and a middle particle size mitigate the stress dip to some extent, whereas irregular particle shape exacerbates it. Comparison of the results from different packing methods reveals that larger repose angle and more pronounced stress dip are observed in confined packing piles compared to that in free packing piles. Considering a growth rate of less than 5 %, the average vertical stress under the sand silo reaches saturation state. Moreover, the pressure on the silo wall increases with the height of silo pile but remains somewhat lower than predicted by the Ketchum equation and current design values.

Variation and attribution of probable maximum precipitation of China using a high-resolution dataset in a changing climate

Abstract. Accurate assessment of the probable maximum precipitation (PMP) is crucial in assessing the resilience of high-risk water infrastructures, water resource management, and hydrological hazard mitigation. Conventionally, PMP is estimated based on a static climate assumption and is constrained by the insufficient spatial resolution of ground observations, thus neglecting the spatial heterogeneity and temporal variability of climate systems. Such assumptions are critical, especially for China, which is highly vulnerable to global warming in ∼ 100 000 existing reservoirs. Here, we use the finest-spatiotemporal-resolution (1 d and 1 km) precipitation dataset from an ensemble of machine learning algorithms to present the spatial distribution of 1 d PMP based on the improved Hershfield method. Current reservoir design values, a quasi-global satellite-based PMP database, and in situ precipitation are used to benchmark against our results. The 35-year running trend from 1961–1995 to 1980–2014 is quantified and partitioned, followed by future projections using the Coupled Model Inter-comparison Project Phase 6 simulations under two scenarios. We find that the national PMP generally decreases from southeast to northwest and is typically dominated by the high variability of precipitation extremes in northern China and high intensity in southern China. Though consistent with previous project design values, our PMP calculations present underestimations by comparing them with satellite and in situ results due to differences in spatial scales and computation methods. Interannual variability, instead of the intensification of precipitation extremes, dominates the PMP running trends on a national scale. Climate change, mainly attributed to land–atmosphere coupling effects, leads to a widespread increase (> 20 %) in PMP across the country under the SSP126 scenario, which is projected to be higher along with the intensification of CO2 emissions. Our observation- and modeling-based results can provide valuable implications for water managers under a changing climate.

Changes in design precipitation over the Nordic-Baltic region as given by convection-permitting climate simulations

The increased risk of flooding due to global warming and subsequent heavy rainfall events in the Nordic-Baltic region, call for recommendations directed at long-term planning. One example of such recommendations are climate change allowances. These are often based on expected changes in design precipitation as given by climate model simulations, and are used as a buffer on top of current design values to avoid a future increased damage potential as a consequence of climate change. We here compute expected changes in precipitation design values, so-called climate factors (CFs), for the Nordic-Baltic region, based on 3 km convection permitting simulations from the Nordic Convection Permitting Climate Projections project. These have the advantage of explicitly resolving convection, which has been shown to be the main contributor to increased rainfall. We assess the dependence of the CFs on rainfall duration, return period, and geographical location, focusing on the summer (convective) season, short durations and the high emission scenario RCP8.5. We also compare these CFs to those computed from a non-convection permitting regional climate model ensemble.We found higher CFs for the longer return period, with only few exceptions, and distinctly higher CFs going from daily to sub-daily durations. However, the different simulations give conflicting results for very short-duration rainfall (<3 h). The huge difference in the climate sensitivity of driving GCMs dominates the magnitude of estimated return levels. Our analysis is shaped by the high computational costs of running convection permitting models, resulting in a very limited ensemble (3 members) representing a single emission scenario (RCP8.5). Therefore, we believe that combining results from convection permitting simulations with a larger ensemble (21 members) of non-convection permitting simulations adds value to the assessment of robust climate change allowances for heavy precipitation in the Nordic-Baltic region.

Performance of a novel central heating system combined with personalized heating devices

This study presents a novel central heating system that combines a conventional central heating network with personalized heating devices. The central heating network is designed to meet the basic heating demand, the indoor room temperature of which is lower than the current design values. Personalized heating devices are installed at the entrance of each indoor heating network to meet the personalized room temperature demand. The system can realize low-temperature heating when spaces are vacant and meet different room temperature demands among end users. The performance of the novel heating system is analyzed and compared with that of a conventional central heating system in terms of energy consumption and CO2 emissions under the climate conditions of Beijing and Harbin. Four types of personalized heating devices, namely, solar heaters, air source heat pumps, electrical heaters, and natural gas heaters, are discussed, and the scenarios of the four typical indoor temperature-setting modes are analyzed. When the basic room temperature is 12 °C, the maximum water supply temperatures of the central heating network is reduced from 75 °C of the traditional system to 45.8 °C (Beijing) and 52 °C (in Harbin). Under the four typical indoor temperature setting modes, the energy-saving ratio and CO2 emission reduction of the novel system are promising. In particular, if solar energy is used as the heat source of the personalized heating device in Beijing and Harbin, the primary energy consumption can be reduced by 46.3–75.7 % and 29.4–68.2 %, and CO2 emissions can be reduced by 44.4–74.5 % and 25.2–54.4 %, respectively. For all the discussed scenarios, static payback time is 1.5–8.8 y and 1.0–6.8 y in Beijing and Harbin, respectively.

Flexural properties of visually graded southern pine 2×4 and 2×6 structural lumber

Flexural properties of visually graded southern pine structural lumber were evaluated. Several grade controlling characteristics were considered relative to bending properties and compared with current design values. A total of 751 southern pine lumber specimens were obtained from a broad spectrum of regions in the southeastern United States. Visually graded No. 2, nominally two inch thick specimens, in four and six inch widths, were obtained from commercial sawmills. All specimens were evaluated by a certified grader in the laboratory. Actual dimensions, weight, and moisture content (MC) were measured. Growth and manufacturing related characteristics were identified and classified into two categories: strength reducing characteristics (SRC) and grade reducing characteristics (GRC). Specific gravity (SG), bending modulus of elasticity (MOE), and modulus of rupture (MOR), were determined for each specimen. The presence of knots was identified as the most significant SRC; their presence had the most significant impact on SG, MOE and MOR. For GRC, specimens with knots, warp and specimens that fell into the category none, were significantly lower in SG, MOE and MOR. MOE and the allowable design bending strength values yielded in this study met the current design value criteria for both widths tested.

Multivariate Dam-Site Flood Frequency Analysis of the Three Gorges Reservoir Considering Future Reservoir Regulation and Precipitation

Under a changing environment, the current hydrological design values derived from historical flood data for the Three Gorges Reservoir (TGR) might be no longer applicable due to the newly-built reservoirs upstream from the TGR and the changes in climatic conditions. In this study, we perform a multivariate dam-site flood frequency analysis for the TGR considering future reservoir regulation and summer precipitation. The Xinanjiang model and Muskingum routing method are used to reconstruct the dam-site flood variables during the operation period of the TGR. Then the distributions of the dam-site flood peak and flood volumes with durations of 3, 7, 15, and 30 days are built by Pearson type III (PIII) distribution with time-varying parameters, which are expressed as functions of both reservoir index and summer precipitation anomaly (SPA). The multivariate joint distribution of the dam-site flood variables is constructed by a 5-D C-vine copula. Finally, by using the criteria of annual average reliability (AAR) associated with the exceedance probabilities of OR, AND and Kendall, we derive the multivariate dam-site design floods for the TGR from the predicted flood distributions during the future operation period of the reservoir. The results indicate that the mean values of all flood variables are positively linked to SPA and negatively linked to RI. In the future, the flood mean values are predicted to present a dramatic decrease due to the regulation of the reservoirs upstream from the TGR. As the result, the design dam-site floods in the future will be smaller than those derived from historical flood distributions. This finding indicates that the TGR would have smaller flood risk in the future.

Interstate transport of ozone in eastern United States: An analysis of the impact of southeastern states’ emissions in 2017

Abstract To meet the requirements of the Clean Air Act's “good neighbor” provision, it is necessary to quantify the interstate transport of air pollution and determine if upwind states significantly contribute to noncompliance with the National Ambient Air Quality Standards (NAAQS) at downwind states. This study aims to estimate the contributions of ten southeastern states (Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia) to ozone (O3), and identify significant associations with nonattainment or maintenance at monitors across the eastern United States (US) in 2017. Two widely used air quality models, the Comprehensive Air quality Model with extensions (CAMx) and the Community Multiscale Air Quality model (CMAQ), using different versions of the Carbon Bond (CB) chemical mechanism, were applied to predict 2017 O3 design values (DVFs) from 2011 O3 design values (DVCs) at the US Environmental Protection Agency's (EPA) Air Quality System (AQS) sites throughout the eastern US. Since 2017 design values are already published, the accuracy of the EPA-recommended modeling methodology for projecting current design values into the future only by changing the emissions was evaluated. The assumption that good model performance in the base year would result in accurate future year ozone projections was tested. In general, CAMx/CB6r2 simulated higher DVFs than CMAQ/CB05, with an average difference of 0.5 ppb. As a result, this study identified 24 sites in the eastern US as nonattainment (DVF ≥ 76 ppb) with CAMx/CB6r2 compared to only 16 sites with CMAQ/CB05. Using monitor cell relative response factors (RRFs) instead of 3×3 cell matrix maximum RRFs (the approach used in EPA's proposed Cross-State Air Pollution Rule (CSAPR) modeling) (EPA, 2015a), led to higher DVFs at some monitors and lower DVFs at others. Source apportionment analysis with the CAMx Anthropogenic Precursor Culpability Assessment (APCA) probing tool revealed that NOx emissions dominated over VOC emissions in contributing to O3 in downwind states. Contributions of total anthropogenic NOx emissions and contributions of Electric Generating Unit (EGU) NOx emissions from the southeastern states to O3 at nonattainment and maintenance sites were quantified separately using CAMx/APCA as well as CMAQ/zero-out simulations. Contributions obtained from CAMx/APCA were typically larger than the contributions obtained from CMAQ/zero-out. Therefore, a “significant contribution” determined by CAMx/APCA may be insignificant according to CMAQ/zero-out. “Significant contribution” was defined as an impact larger than 1% of the 2008 O3 NAAQS (i.e., ≥ 0.76 ppb). Alabama, Kentucky, Mississippi, Tennessee, Virginia and West Virginia were linked to 2, 3, 1, 1, 6 and 5 nonattainment sites with CAMx/APCA, while only Kentucky, Virginia and West Virginia were linked to 2, 3 and 2 nonattainment sites with CMAQ/zero-out. Additionally, for significant linkages, EGU NOx contributions were 10–55% of the total anthropogenic NOx contributions. The information produced in this study can be used by southeastern states to help develop “good neighbor” State Implementation Plans (SIPs).

High-cycle fatigue interaction between soil foundation and concrete slab under moving wheel-type loads

Small-scale fatigue experiments were conducted to investigate failure modes of the coupled system of soil foundation and concrete slab subjected to wheel-type moving loads. Based on these experiments, the numerical fatigue simulation was validated by integrating constitutive models of cracked concrete and soil foundations. The finite element code used in this study is built by combining the multi-directional fixed crack model of concrete with the multi-yield surface plasticity for nonlinear shear and volumetric fatigue of soil. The computed deflections and failure modes of the pavement system show close correlation with experiments. To clarify the real working conditions, full-scale modeling was investigated as well. The results depict that the necessary and sufficient slab thickness varies nonlinearly according to the soil rigidity, and that the medium compacted soil foundation requires the thicker slabs rather than the current design value rooted in a beam theory on elastic foundation. Thus, a key factor to revise the design scheme is proposed in terms of the balanced slab thickness associated with the nonlinearity of soil foundation.

Towards Zero Emissions from Fossil Fuel Power Stations

It is projected that net zero carbon emissions are required early in the second half of this century to maintain global temperature increase to below 2 °C. To achieve this, the CO2 capture rates in CO2 Capture and Storage (CCS) chains would need to be higher than most current design values, ranging from 85% to 90%. In this study, results from previous studies were assessed to explore the potential to increase CO2 capture rates across the range of capture routes for power stations including post-/pre-combustion capture and oxyfuel. Next, using the most advanced technology for CO2-capture from power stations, i.e. liquid absorbent based post-combustion CO2-capture, the techno-economic performance of a capture process at higher capture rates (>90%) has been assessed. The work has focused on an initial standard design using a 30 wt% Monoethanolamine (MEA) solution and investigated the impact of increasing capture rates on the technical performance, in particular the specific reboiler duty. It was then extended to a number of cases studies, also allowing for process design modifications that aimed to minimise reboiler duty. The overall results are compared to the standard design in terms of process performance, capital costs and operational costs.Additionally, the use of biomass in combination with CCS by co-combustion was incorporated and the impact of fuel prices was assessed.

Critical discussion of perpendicular to grain tension testing of structural timber – case study on the European hardwoods ash, beech and maple

ABSTRACT Knowledge about perpendicular to grain tension behavior of wood is essential, since in construction tension stresses perpendicular to grain cannot be avoided completely. Especially for hardwoods, the data basis is scarce. EN 338 design values are with 0.6 N/mm² characteristic strength set very low. The US-American National Design Specifications even set this value to zero and make local reinforcements mandatory. This paper compares strength and stiffness values attained with newly-designed, little, prismatic specimens and EN 408 structural timber specimens to evaluate the current European design values. Little specimen’s characteristic strength values range from 7.2 to 10.6 N/mm² and are assumed to be real material properties. EN 408 specimen values are with approximately 4.0 N/mm² lower. These lower values are mainly due to stress peaks introduced by the force introduction. Strength values attained for the medium-dense European hardwoods beech, ash and maple exceed EN 338 design values by a factor of six to seven. Adaptation of the EN 338 design value is not recommended, though. The abundance of influencing factors makes clear that the design value and the ensuing design code have to be synchronized carefully by tedious testing in order to make use of the perpendicular to grain tension strength potential of the selected hardwoods.

Design of the Online Gross γ Monitoring Instrument at the Exit of the Helium Purification System in HTR-PM

After the successful construction and operation experience of the 10 MW high-temperature gas-cooled reactor (HTR-10), a high-temperature gas-cooled pebble-bed modular (HTR-PM) demonstration plant is under construction in Shidao Bay, Rongcheng City, Shandong province, China. An online gross γ monitoring instrument has been designed and placed at the exit of the helium purification system (HPS) of HTR-PM and is used to detect the activity concentration in the primary circuit after purification. The source terms in the primary loop of HTR-PM and the helium purification process were described. The detailed configuration of the gross γ monitoring instrument was presented in detail. The Monte Carlo method was used to simulate the detection efficiency of the monitoring system. Since the actual source terms in the primary loop of HTR-PM may be different than the current design values, a sensitivity analysis of the detection efficiency was implemented based on different relative proportions of the nuclides. The accuracy and resolution of the NaI(Tl) detector were discussed as well.

Plastic Packaging Material Value Conservation and Evident of the Consumers’ Acceptance

Virgin plastic pellets are widely used as raw materials in flexible plastic packaging which generate abundant postconsumer plastic waste. The widespread use of recycled plastic pellets as raw materials will reduce plastic waste generation significantly. However, substitution of virgin materials need high quality of recycled plastic pellets which produced from good quality of plastic waste. Design for material value conservation in this case study was a trial implementation of design principles of plastic bag in order to minimize its value degradation of plastic waste, and therefore increase its acceptance by plastic recycling industries. A Structural Equation Modelling (SEM) with Lisrel 8.8 software used as tool of analysis in evaluating consumer acceptance of the two types of design paradigm, current design and material value conservation based design. The results indicated that consumers accepted both type of packaging. With final standard factor loading, the proposed design indicated slightly better correlation coefficients: 0.46 for Ease of Information Delivery and 0.74 for Informational Content variables, better than current design with 0.44 and 0.73 coefficients. Widespread implementation of design for material value conservation will save virgin plastic consumption for plastic packaging production, reduce plastic waste generation as well as support material resource conservation in a better condition of environment. The social and economic benefit will also be obtained as multiplier effect of material value conservation.

BENDING STRENGTH AND STIFFNESS OF NO. 2 GRADE SOUTHERN PINE LUMBER

Southern pine is the most important species group planted and used for lumber products in the United States. Most southern pine trees come from managed forests, with relatively short rotations and excellent growth yields. The accelerated growth volume allows trees to reach merchantable size in 16- 22 yr. However, these trees may contain large amounts of juvenile wood which can negatively impact the bending properties of lumber. In 2010, the Southern Pine Inspection Bureau (SPIB) began to reevaluate the mechanical properties of southern pine lumber, which resulted in changes in design values. The objective of the study herein was to summarize the growth characteristics and bending properties of No. 2 grade 24, 26, 28, and 210 samples collected from across the geographical growing range (southern United States). Each piece met the requirements for No. 2 grade southern pine lumber. Overall, 34.5% of the sample contained pith, averaged 4.6 rings per inch, and contained 43.8% latewood. The sample’s average specific gravity,MOE, and MOR were 0.54, 10.1 GPa, and 41.7 MPa, respectively. The mean MOE found in this study was higher than the current design value required for No. 2 southern pine lumber. For allowable design bending strength (Fb), the results showed that, as dimension stock size increased, the Fb decreased from 11.2 MPa for 2 4 s to 7.1MPa for 2 10 s. The Fb values determined herein exceeded the new published design value and also met the previous SPIB design values. These results suggest that the timber resource quality might have increased since the housing crisis of 2008-2010.

Анализ результатов натурных испытаний сосредоточенных заземлителей при импульсных токах

The extent to which an overhead power line is protected from lightning strokes depends to a considerable degree on the values of surge impedances of line support grounding conductors rather than on their impedances at the power frequency that are specified in the Electrical Installations Code (PUE). Hitherto, the results from calculations of grounding conductor surge impedances had to be compared with the results of tests carried out with currents around 20 kA, whereas the lightning stroke current design value is 100 kA. Such an approach would be valid provided that the grounding conductor parameters were similar to those under the conditions of lightning currents. A method for calculating a rod type grounding conductor parameters under the conditions of real lightning currents is developed. The calculation results have shown that the grounding conductor surge impedance is essentially lower under lightning current conditions; moreover, its qualitative characteristics differ from those obtained from the tests. For example, with currents around 100 kA, the surge impedance increases with increasing the grounding conductor sizes instead of decreasing as is the case with currents equal to 20 kA.

Bending strength and stiffness of loblolly pine lumber from intensively managed stands located on the Georgia Lower Coastal Plain

Loblolly pine is increasingly grown on intensively managed plantation forests that yield excellent growth; however, lumber cut from these trees often contains a large percentage of juvenile wood which negatively impacts strength and stiffness. Because of changing forest management and mill practices the design values for visually graded southern pine were updated in 2013 to more accurately account for the material properties available in commerce. This study was undertaken to assess the bending strength and stiffness of loblolly pine lumber from intensively managed stands located on the Georgia Lower Coastal Plain. Eight hundred and forty-one pieces of lumber sawn from 93 trees age 24–33 years were tested in four-point bending according to ASTM International standards. The No. 1 grade MOE15 (11.9 GPa) was greater than the current (11.0 GPa) design value and comparable to the previous (11.7 GPa) design value. The No. 2 grade MOE15 (10.6 GPa) was greater than the current (9.7 GPa) design value but slightly less than the previous (11.0 GPa) design values. The No. 3 grade MOE15 (9.3 GPa) was between the current (9.0 GPa) design value and the previous (9.7 GPa) design value. Altogether, these results point to the MOE15 mean values being reasonably comparable to the previous design values and currently meeting or exceeding the current design values for visually graded southern pine lumber.

A new seismic hazard analysis using FOSM algorithms

From recent lessons, it is evident that earthquake prediction is immature and impractical as of now. Under the circumstances, seismic hazard analysis is considered a more practical approach for earthquake hazard mitigation, by estimating the annual rate of earthquake ground motions (or seismic hazard) based on seismicity and other geological evidences. Like other earthquake studies for the high-seismicity region around Taiwan, this study aims to conduct a new seismic hazard assessment for the region using the well-established FOSM (first-order second-moment) algorithm, on the record of 55,000 earthquakes observed in the past 110 years. The new seismic hazard analysis from a different perspective shows that the annual rate for earthquake-induced PGA to exceed the current design value (i.e., 0.23g) in two major cities in Taiwan should be relatively low, with it no greater than 0.0006 per year. Besides, the FOSM estimates were found very close to those with Monte Carlo Simulation (MCS), mainly because the skewness of the three random variables (i.e., earthquake magnitude, location, and model error) considered in the probabilistic analysis is not very large.

An extended approach to calculate the ozone relative response factors used in the attainment demonstration for the National Ambient Air Quality Standards

With the promulgation of the National Ambient Air Quality Standards (NAAQS or standard) for 8-hr ozone (O3), the U.S. Environmental Protection Agency (EPA) issued modeling guidance that advocated the use of results from photochemical air quality models in a relative sense. In doing so, the EPA provided guidance on how to calculate relative response factors (RRFs) that can project current design value (DV) mixing ratios into the future for the purpose of determining the attainment status with respect to the O3 standard. The RRFs recommended by the EPA represent the average response of the photochemical model over a broad range of O3 mixing ratios above a specified cutoff threshold. However, it is known that O3 response to emission reductions of limiting precursors (i.e., NOx and/or VOC) is greater on days with higher O3 mixing ratios compared to days with lower mixing ratios. In this study, we present a segmented RRF concept termed band-RRF, which takes into account the different model responses at different O3 mixing ratios. The new band-RRF concept is demonstrated in the San Joaquin Valley (SJV) region of California for the 1-hr and 8-hr O3 standards. The 1-hr O3 analysis is relevant to work done in support of the SJV O3 State Implementation Plan (SIP) submitted to the EPA in 2013. The 8-hr example for the future year of 2019 is presented for illustrative purposes only. Further work will be conducted with attainment deadline of 2032 as part of upcoming SIPs for the 0.075 parts per million (ppm) 8-hr O3 standard. The applicability of the band-RRF concept to the particulate matter (PM2.5) standards is also discussed.Implications:Results of photochemical models are used in regulatory applications in a relative sense using relative response factors (RRFs), which represent the impacts of emissions reductions over a wide range of ozone (O3) values. It is possible to extend the concept of RRFs to account for the fact that higher O3 mixing ratios (both 1-hr and 8-hr) respond more to emissions controls of limiting precursors than do lower O3 mixing ratios. We demonstrate this extended concept, termed band-RRF, for the 1-hr and 8-hr O3 National Ambient Air Quality Standard (NAAQS or standard) in the San Joaquin Valley of California. This extension can also be made applicable to the 24-hr PM2.5 and annual PM2.5 standards.

Probabilistic assessment of the occupant load density in retail buildings

The occupant load density is a crucial parameter for the design of the means of egress in buildings. In retail buildings the occupant load density is highly influenced by the individual׳s choice and the necessity of a person to visit the store. This causes a high variability of the occupant load density in time. An accurate representation of this variability will provide a basis for enhancing fire safety design. In this paper, a probabilistic approach is used to describe the variability of the occupant load density over a year, based on long-term data of customer frequencies in combination with methods from the queuing theory the distribution of the occupant load density is derived for four different types of retail chains. It is shown that the type of a retail chain has a large influence on the distribution of the occupant load density and that the exceedance probability of current design values in different standards is very small. A method is proposed to derive design values for a performance based design on the basis of probabilistic models for the occupant load density. In addition, the developed probabilistic models describing the number of occupants in a store, allow the assessment of the occupant load density for other types of retail chains, even with incomplete data.

경골목구조에서 구조재와 오에스비로 구성된 못 접합부의 인발 및 전단성능

The nailed joints in wood construction are commonly designed to resist and carry the lateral load but also subject to withdrawal force like uplift load due to the wind. This research was conducted to evaluate the performance of nailed joint composed of dimension lumber and sheathing materials through the nail withdrawal and unsymmetric double shear joint test, and then compared to current design values. The withdrawal strength was greatly dependant on wood specific gravity, and the withdrawal strength of I-joist with OSB showed higher value in spite of low specific gravity. The maximum withdrawal loads were greater than that of derived current design values about 5 times. The lateral resistance of Japanese larch/OSB nailed joints was higher than that of SPF/OSB nailed joint, and derived allowable lateral strength of nailed joints in this study exceeded the current design values. The failure mode of nailed joints was primarily due to the nail bending and this tendency was notable in SPF/OSB nailed joint.

Assessment of seismic hazard associated with the Meishan fault in Central Taiwan

According to the Central Geological Survey Taiwan (CGST), the Meishan fault in Central Taiwan, which induced a catastrophic earthquake in 1906, is considered capable of triggering equivalent events with a return period of 162 years. Therefore, as the next event is expected around 2070, the Meishan fault poses a high level of earthquake risk in Central Taiwan, especially for those cities and townships very close to the fault. However, the best-estimate return period (162 years) and earthquake magnitude (7.1 M L) reported by the CGST must be subject to some uncertainty, because such an event is very unlikely to recur every 162 years. Therefore, this study carried out a series of seismic hazard assessments for three major cities close to the Meishan fault, with the uncertainty of the best-estimate information being determined using the Rosenblueth algorithm. The results show that for Chaiyi city, which the Meishan fault passes through, the probability of the current design value (i.e., PGA = 0.33 g) being exceeded by the earthquake motion induced by the Meishan fault in the next 50 years would be as high as 55 %. Therefore, further studies should be carried out to obtain a better understanding of the Meishan fault, to develop a robust hazard mitigation plan for nearby cities.