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Chen J.-S.,National Cheng Kung University | Lee C.-T.,National Cheng Kung University | Lin Y.-Y.,Sinotech Engineering Consultants
Journal of Materials in Civil Engineering | Year: 2017

Porous asphalt concrete (PAC) is a particular type of asphalt mixture that has a high content of air voids that is generated because of an open-graded design. The objective of the study is to investigate the effect of the engineering properties of PAC on field performance. Three binders were selected for evaluation: conventional asphalt, polymer-modified asphalt, and highly modified asphalt. Comprehensive laboratory tests, including permeability, resistance to draindown, resistance to disintegration, resistance to rutting, and resistance to indirect traction, were conducted to evaluate the engineering properties of PAC mixtures. Stiff binders were shown to resist against particle loss and to enhance durability of PAC mixes through thick asphalt binder films. According to the laboratory results, a test road was constructed to monitor the performance of PAC pavements with aggregates having a nominal maximum size of 19 mm. Surveys for pavement performance were conducted at scheduled intervals. Test results indicated that the use of polymer-modified binders in surface courses was technically superior to that of traditional asphalt. There were indications of drainage improvement by replacement of conventional asphalt with polymer-modified binders according to measurements in the field. Porous asphalt-wearing layers were shown to maintain drainability for more than 8 years in this study. The engineering properties of PAC mixes obtained from the laboratory corresponded well with pavement performance evaluated in the field. © 2016 American Society of Civil Engineers.

Lo C.-M.,Chienkuo Technical University | Lee C.-F.,Sinotech Engineering Consultants | Chou H.-T.,National Central University | Lin M.-L.,National Taiwan University
Landslides | Year: 2014

This study focused on the landslide case at Su-Hua Highway 115.9k, Taiwan. A preliminary investigation was conducted on geomorphologic features change and landslide mechanisms using digital elevation models, geographical maps, and remote sensing images at different times in conjunction with geological surveys and analysis results. Using the results of geological surveys and physical model experiments, we constructed a discrete element method to simulate the process of landslide movement. The results revealed deformation in the metamorphic rock slopes upstream of 115.9k. The slopes around the erosion gully upstream presented visible slope toes cutting and tension cracks at the crest as well as unstable rock masses. According to the results of numerical simulation for typhoon Megi event, intense rains could induce slippage in the rock debris/masses in the source area, initially at a speed of 5-20 m/s. Subsequently, steeper terrain could cause the rock debris/masses to accelerate to form a high-speed (>30 m/s) debris slide quickly moving downstream to form an alluvial fan downstream by the sea. © 2013 Springer-Verlag Berlin Heidelberg.

Chen S.-C.,National Chung Hsing University | Chou H.-T.,National Central University | Wu C.-H.,Feng Chia University | Lin B.-S.,Sinotech Engineering Consultants
Engineering Geology | Year: 2014

Fractured and high-permeability Miocene formations, exhibiting shallow soil layers and dense faults, and an increasing number of heavy rainfall events have caused severe and frequent landslides in the Shenmu watershed of Central Taiwan. The Shenmu watershed exhibited a landslide ratio that was typically greater than 1.0% during heavy rainfall events between 1996 and 2009, and can be considered one of the most landslide-prone areas in Taiwan. The landslide ratio in the lower hillslopes is approximately 2.8 to 43.3 times greater compared with that in the upper hillslopes. Analyzing based on a self-organized criticality (SOC) perspective indicated that the β value of the Shenmu watershed (1.24-1.26) was the lowest among landslide-prone areas, implying that small landslides dominated the distribution of landslides documented in available records. The six large landslides that occurred include four shallow landsides and two deep-seated landslides (with a landslide depth greater than 10m). Approximately 82.3% of the small landslides constituted bank-erosion landslides in the downstream watershed, whereas 96.2% of the large landslides occurred in upstream areas with dense faults. Large landslides occurred during only heavy rainfall events in which the accumulated rainfall was greater than 1000mm in fractured and high-permeability strata with dense faults. The large landslides deposited considerable amounts of sediment into streams, inducing significant bank-erosion landslides in the downstream watershed. Bank erosion in the downstream watershed caused additional small landslides along the river. Large landslides were typically caused by a fault density of 693.6m/km2, fractured strata with a permeability of 10-3 to 10-4m/s, and high levels of accumulated rainfall exceeding 1000mm. The apparent increase in bank erosion, which increased from 103% to 136% between 1996 and 2009, resulted from an increasing number of heavy rainfall events and the amount of sediment deposition caused by major landslides. Frequent landslides result from the increasing number of heavy rainfall events, fractured rock exhibiting dense faults, and steep and shallow-soil morphology in the Shenmu watershed. © 2013 Elsevier B.V.

Lo W.-C.,National Chiao Tung University | Tsao T.-C.,Sinotech Engineering Consultants | Hsu C.-H.,Sinotech Engineering Consultants
Natural Hazards | Year: 2012

In quantitative risk analyses for natural hazards, vulnerability can be expressed as the ratio of reconstruction, replacement or reproduction expenses due to a damage caused by a certain process intensity and the original value of the element at risk exposed. To discuss the building vulnerability under debris flow events, the ratio is mostly related to debris flow inundation height, building materials and building values. Different types of buildings would resist to the impact of debris flows differently, resulting in different damage levels even under the same inundation height. After debris flow events, the damages to a building include the content loss and the structure loss, which is also variable due to the individual building conditions. This study proposes a flowchart to establish building vulnerability curves through estimating the damages to buildings after debris flow hazards. The losses of content and structure are firstly calculated separately to obtain the loss ratios with respect to original buildings. Secondly, by combining the content and structure loss ratio, the building vulnerability function is derived. In this paper, the original building content value was obtained from governmental statistic records and was based on the market price, and the structure value was received from a regional architecture office. The losses resulting from debris flow impacts were synthetically derived following field surveys. To combine the content and structure losses, a unit building with a floor area of 60 m 2 was assumed. The result shows that due to a higher percentage of content value compared with the total building value, the loss ratio resulting from debris flows in Taiwan is higher compared with European studies, in particular with respect to high-frequency but low-magnitude events. The concept of obtaining building vulnerability is particularly suitable for regions where well-documented building loss records are unavailable. © 2012 Springer Science+Business Media B.V.

Lin T.K.,Sinotech Engineering Consultants | Hung S.L.,National Chiao Tung University | Huang C.S.,National Chiao Tung University
International Journal of Structural Stability and Dynamics | Year: 2012

This paper intends to detect the damage locations for building structures under an earthquake excitation using a novel substructure-based FRF approach with a damage location index (SubFRFDI). An Imote2.NET-based wireless structural health monitoring system was developed and employed in the experimental studies for the sake of deployment flexibility, low maintenance cost, low power consumption, self-organization capability, and wireless communication capability. The feasibility of the proposed approach for damage detection was examined using the numerical response of a six-storey shear plane frame structure subjected to a base excitation. The results demonstrate that the SubFRFDI can be successfully used to identify the damage of different levels at a single site or multiple sites. The SubFRFDI is independent of the responses to various input earthquake excitations. Even with the addition of noises, the SubFRFDI still functions well. The feasibility and robustness of the proposed Imote2.NET-based wireless structural health monitoring system were assessed using a 1/8-scale three-storey steel-frame model. Following this, the proposed SubFRFDI was further applied to identifying the damage locations in a 1/4-scale six-storey steel structure with the proposed Imote2.NET-based wireless monitoring system. It was confirmed experimentally that good data transportation quality can be achieved via reliable data transmission and sensing protocol in identifying the structural dynamic properties, and the proposed SubFRFDI can be used to identify the damage locations effectively. © 2012 World Scientific Publishing Company.

Lee C.-F.,Sinotech Engineering Consultants | Chou H.-T.,National Central University | Capart H.,National Taiwan University
Powder Technology | Year: 2013

The axial segregation of granular flows in rotating drums is closely correlated to the material properties and side-wall friction. In this study, experimental work with two different types of sidewall roughness is performed to characterize the frictional effect of the side walls. In one case both walls are smooth and in the other each sidewall has a different roughness. The evolution of the Rayleigh-instability core inside the granular assembly varies with the aspect ratio of the drums. By increasing the Froude number, the axial banding expands with increasing side-wall roughness. The asymmetrical banding stripe is enhanced by the differential frictional roughness on either side wall. Axial segregation is driven by both the variation in the size ratio of the mixtures and the drum geometrical parameters. © 2012 Elsevier B.V.

Lahousse T.,National Taiwan University | Chang K.T.,Kainan University | Lin Y.H.,Sinotech Engineering Consultants
Natural Hazards and Earth System Science | Year: 2011

We developed a multi-scale OBIA (object-based image analysis) landslide detection technique to map shallow landslides in the Baichi watershed, Taiwan, after the 2004 Typhoon Aere event. Our semi-automated detection method selected multiple scales through landslide size statistics analysis for successive classification rounds. The detection performance achieved a modified success rate (MSR) of 86.5% with the training dataset and 86% with the validation dataset. This performance level was due to the multi-scale aspect of our methodology, as the MSR for single scale classification was substantially lower, even after spectral difference segmentation, with a maximum of 74%. Our multi-scale technique was capable of detecting landslides of varying sizes, including very small landslides, up to 95 m2. The method presented certain limitations: the thresholds we established for classification were specific to the study area, to the landslide type in the study area, and to the spectral characteristics of the satellite image. Because updating site-specific and image-specific classification thresholds is easy with OBIA software, our multi-scale technique is expected to be useful for mapping shallow landslides at watershed level. © 2011 Author(s).

Lo C.-M.,Sinotech Engineering Consultants | Lin M.-L.,National Taiwan University | Tang C.-L.,National Taiwan University | Hu J.-C.,National Taiwan University
Engineering Geology | Year: 2011

This paper presents results of a case study on the Hsiaolin catastrophic landslide, including its kinematic process and the geometry of deposition. Based on geomorphologic analysis, the landslide initiated in thick, multi-aged colluvium soils at the headwaters of a small stream upslope of Hsiaolin village. A 3D discrete element program, PFC3D was used to model the kinematic process that led to the landslide and destruction of Hsiaolin village. The landslide advanced from debris slide to debris avalanche during the kinematic process. Assuming a friction coefficient of each particle of 0.1, the predicted maximum velocity was about 70. m/s, a velocity which permits the debris to cross Qishanxi stream and deposit on the opposite bank. Based on simulation results, Hsiaolin village was inundated in 60 to 65. s after failure initiation and at 112. s after the event, the debris avalanche came to rest, forming a landslide dam. © 2011.

Wei Y.-C.,Sinotech Engineering Consultants | Sasanakul I.,University of South Carolina | Abdoun T.,Rensselaer Polytechnic Institute
International Journal of Physical Modelling in Geotechnics | Year: 2016

The main objective of this study is to investigate systematically the lateral earth pressure induced by the cone penetration test (CPT) conducted at various distances from the rigid container wall. A series of centrifuge CPTs were performed in dry Ottawa sand using two miniature penetrometers with diameters of 4 and 12 mm. The CPT locations varied from 2 to 42 times the cone diameter. The change of lateral earth pressure was measured using tactile pressure sensors. Results from this study have shown that the lateral earth pressure change was mainly associated with the initial relative density of soil, the distance away from the testing location and the diameter of the cone penetrometer. The change of lateral pressure can be as large as 150–200 kPa at a distance of 2–4 times the diameter of the CPT. The effect of initial soil relative density on the change of lateral earth pressure was greater when using the 4mm CPT than the 12mm CPT. Some residual lateral pressure was observed after completion of the CPT in dense sand tests. © 2016, ICE Publishing. All Rights Reserved.

Chen S.-J.,National Taiwan University of Science and Technology | Jhang C.,Sinotech Engineering Consultants
Journal of Constructional Steel Research | Year: 2011

This paper describes the study of the low-yield-point (LYP) steel plate shear walls under in-plane load. In the LYP steel plate shear wall system, LYP steel was selected for the steel plate wall while the boundary frame was constructed by the high strength structural steel. A series of experimental studies examined the inelastic shear buckling behavior of the LYP steel plate wall under monotonic in-plane load. The effects of width-to-thickness ratio on the shear buckling of LYP steel plates were examined. The stiffness, strength, deformation, and energy dissipation characteristics were investigated by performing cyclic loading tests on the multistorey LYP steel plate shear walls. Excellent deformation and energy dissipation capacity were obtained for all specimens tested. The LYP steel plate shear wall system is able to exceed 5% of storey drift angle under lateral force. © 2010 Elsevier Ltd. All rights reserved.

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