• Wind and Structures
• /
• v.22 no.2
• /
• pp.133-160
• /
• 2016

Hurricanes are among the most costly natural hazards to impact buildings in coastal regions. Building roofs are designed using the wind load provisions of building codes and standards and, in the case of large buildings, wind tunnel tests. Wind permeable roof claddings like roof pavers are not well dealt with in many existing building codes and standards. The objective of this paper is to develop simple guidance in code format for design of loose-laid roof pavers. Large-scale experiments were performed to investigate the wind loading on concrete roof pavers on the flat roof of a low-rise building in Wall of Wind, a large-scale hurricane testing facility at Florida International University. They included wind blow-off tests and pressure measurements on the top and bottom surfaces of pavers. Based on the experimental results simplified guidelines are developed for design of loose-laid roof pavers against wind uplift. The guidelines are formatted so that use can be made of the existing information in codes and standards such as American Society of Civil Engineering (ASCE) 7-10 standard's pressure coefficients for components and cladding. The effects of the pavers' edge-gap to spacer height ratio and parapet height to building height ratio are included in the guidelines as adjustment factors.

• Computers and Concrete
• /
• v.22 no.6
• /
• pp.573-592
• /
• 2018

An analytical methodology for the calculation of the flexural and the shear capacity of concrete members with Fibre-Reinforced-Polymer (FRP) bars as tensional reinforcement is proposed. The flexural analysis is initially based on the design provisions of ACI 440.1R-15 which have properly been modified to develop general charts that simplify computations and provide hand calculations. The specially developed charts include non-dimensional variables and can easily be applied in sections with various geometrical properties, concrete grade and FRP properties. The proposed shear model combines three theoretical considerations to facilitate calculations. A unified flexural/shear approach is developed in flow chart which can be used to estimate the ultimate strength and the expected failure mode of a concrete beam reinforced with longitudinal FRP bars, with or without transverse reinforcement. The proposed methodology is verified using existing experimental data of 138 beams from the literature, and it predicts the load-bearing capacity and the failure mode with satisfactory accuracy.

• Structural Engineering and Mechanics
• /
• v.90 no.2
• /
• pp.127-142
• /
• 2024

In recent decades, pultruded glass fiber-reinforced polymer (GFRP) members including those of box sections have attracted the attention of researchers. Nevertheless, the lack of uniform and consistent material properties, simplified design methods, and practical design codes have so far been the main barrier for field applications. Consequently, this paper highlights the existing knowledge concerning the flexural behavior of pultruded GFRP profiles and their failure modes. In particulate, it reviews the most commonly accepted design expressions and code provisions addressing the flange local buckling of pultruded GFRP box beams as the most likely failure mode. In addition, the material characterization of GFRP sections is described in detail along with the standard test methods to quantify the material characterization of GFRP laminates. It is shown that the critical flange local buckling stresses of pultruded GFRP box beams can be predicted with reliable accuracy using the expressions promulgated by ASCE (1984) (in which the flange plates are considered simply-supported at web-flange junction) and EUR 27666. The expressions stipulated in ASCE (2010) highly overestimates the critical flange local buckling stresses of GFRP box beams resulting in unconservative predictions.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.30 no.2
• /
• pp.185-189
• /
• 2017

The purpose of earthquake resistant design for typical bridges is the 'No Collapse Design' allowing emergency vehicles just after earthquakes. The Roadway Bridge Design Code provides design provisions to carry out such 'No Collapse Design' with a ductile mechanism and response modification factors given for connections and substructure play key role in this procedure. In case of response modification factors for substructure, the Roadway Bridge Design Code provides values considering ductility and redundancy. On the other hand, 'AASHTO LRFD Bridge Design Specifications' provides values considering additionally an artificial factor according to the bridge importance categories divided into critical, essential and others. In this study, a typical bridge with steel bearing connections and reinforced concrete piers is selected and different response modification factors for substructure are applied with design conditions given in the Roadway Bridge Design Code. Based on the comparison study of the design results, supplementary measures are suggested required by applying different response modification factors for substructure.

• The Research Journal of the Costume Culture
• /
• v.24 no.2
• /
• pp.132-149
• /
• 2016

With the increased importance of design creativity in global fashion marketplaces, there have arisen numerous promotional strategies for new fashion designers in Korea, yet little research has been done on this subject. This study examines the new fashion design promotion policies in Korea and their effects from the designer's perspective. First, we analyzed the contents of twenty-one strategies from thirteen organizations regarding the types of support from the strategies. As a result, four distinct types are identified: new designer recognition; information and consulting support; brand incubating; and marketing support. Next, we performed in-depth one-on-one interviews with eleven designers who had been awarded from one or more of the fashion design incubation policies. The results reveal that the incubating policies' cash rewards and space support are found to be most effective. In terms of the revised fashion and brand consulting policy, "brand operation" had an influence. In addition, fashion the new brand advertisement and marketing policy had positively influenced the "brand development." However, throughout the interview, designers note that the quality of education and information provisions need some improvement. Furthermore, the designers indicate the lack of supervision and professionalism from the marketing departments. Based on this content, this study emphasizes the necessity of an effective fashion design promotion policy, and strategic and consistent support for the whole fashion promotion team. At the minimum, an integrated and united supervision by the organization is necessary and should be taken into consideration.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.2
• /
• pp.93-101
• /
• 2024

Code-compliant seismic design should be essentially applied to realize the so-called emulative performance of precast concrete (PC) lateral force-resisting systems, and this study developed simple procedures to design precast industrial buildings with intermediate precast bearing wall systems considering both the effect of seismic and blast loads. Seismic design provisions specified in ACI 318 and ASCE 7 can be directly adopted, for which the so-called 1.5S_y condition is addressed in PC wall-to-wall and wall-to-base connections. Various coupling options were considered and addressed in the seismic design of wall-to-wall connections for the longitudinal and transverse design directions to secure optimized performance and better economic feasibility. On the other hand, two possible methods were adopted in blast analysis: 1) Equivalent static analysis (ESA) based on the simplified graphic method and 2) Incremental dynamic time-history analysis (IDTHA). The ESA is physically austere to use in practice for a typical industrial PC-bearing wall system. Still, it showed an overestimating trend in terms of the lateral deformation. The coupling action between precast wall segments appears to be inevitably required due to substantially large blast loads compared to seismic loads with increasing blast risk levels. Even with the coupled-precast shear walls, the design outcome obtained from the ESA method might not be entirely satisfactory to the drift criteria presented by the ASCE Blast Design Manual. This drawback can be overcome by addressing the IDTHA method, where all the design criteria were fully satisfied with precast shear walls' non-coupling and group-coupling strength, where each individual or grouped shear fence was designed to possess 1.5S_y for the seismic design.

• Journal of the Korea Concrete Institute
• /
• v.28 no.6
• /
• pp.655-663
• /
• 2016

The present study shows the moment-average curvature relationship and effective inertia moment of RC beams obtained from the nonlinear analysis based on the parabola-rectangular stress-strain curve defined in EC-2 code. The variables examined are concrete strength and steel ratio, and moment-average curvature relationship and effective inertia moment obtained are compared with those of the current KCI provisions. As the results of the comparison, the followings could be said: Since the KCI provisions(the Branson method) were originally derived based on the experimental data ranged from 2.2 to 4 of $M/M_{cr}$ and 1.3 to 3.5 of $I_{ut}/I_{cr}$, thereby within these ranges the inertia moments obtained from the nonlinear analysis are closely agreed with those predicted by the Branson method. However, beyond those range the remarkable difference could be found between the two results. In particular, for beams having low steel ratio the inertia moment resulted from the nonlinear analysis are significantly smaller than those obtained from the KCI(Branson) method. This result may imply that the deflection of lightly reinforced members, such as slabs in buildings, becomes much larger than those calculated according to the current design provisions.

• Journal of Korea Trade
• /
• v.24 no.4
• /
• pp.49-70
• /
• 2020

Purpose - The UCP is recognized as the governing law for L/C transactions, but it covers only the general details of the transaction and does not cover all complex practices. In view of this limitation, this paper examines a negotiation transaction which is most actively utilized in L/C transactions via a thorough review of the UCP provisions, analyzes the problems of the negotiation clause in the UCP, and suggests appropriate countermeasures to deal with unnecessary litigation costs. By doing so, the parties involved in the negotiation transaction would be able to avoid financial costs such as having to pay for lawsuits. Design/methodology - The present study first differentiates the general types of L/Cs (e.g., sight payment L/C, deferred payment L/C, acceptance L/C, and negotiation L/C), explains and the Article 2 and Article 12(b) of the UCP 600 where the term 'negotiation' is used, digs into the drawbacks of 'negotiation' occurring under the UCP 600, and discusses solutions to the problems found by analyzing the drawbacks descriptively. Findings - After a review of the UCP provisions on negotiation in detail, several possible problems which may occur in practice were discovered. First, as the UCP stipulates, the negotiating bank will want to delay payment to the maximum extent possible and make payment on the banking day on which the issuing bank reimburses the amount. This may lead the beneficiary towards bankruptcy or put it in financial crisis. Second, when a fraudulent transaction occurs, the negotiating bank can neither request the issuing bank to reimburse nor can it exercise its recourse right against the beneficiary because it has obtained all the rights of the beneficiary by purchasing the documents. Third, there is a practice in which the beneficiary sells the documents to its transaction bank which is not the nominated bank if the nominated bank specified in the credit is located in a third country or the exporter has no relationship with the nominated bank in the credit. In this case, whether to accept this and reimburse the non-nominated negotiating bank entirely depends on the issuing bank's decision even though such practice frequently occurs in Korea. Originality/value - There has been little research effort pertaining to negotiation transactions in detail even though negotiation L/C transactions account for around 70% in world trade notwithstanding deferred payment L/Cs and acceptance L/Cs that are also negotiated in practice. Thus, if the negotiations clause under the UCP 600 provisions were reviewed and the drawbacks of the negotiation transactions most actively used in L/C transactions were identified and examined, specific countermeasures could ultimately help smoothen the operation of L/C transactions and prevent financial losses.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.6
• /
• pp.67-74
• /
• 2010

Because of the difference between the actual and computed eccentricity of buildings, symmetrical buildings will be affected by torsion. In provisions, accidental eccentricity is intended to cover the effect of several factors, such as unfavorable distributions of dead- and live-load masses and the rotational component of ground motion about a vertical axis. The torsional amplification factor is introduced to reduce the vulnerability of torsionally imbalanced buildings. The effect of the torsional amplification factor is observed for a symmetric rectangular building with various aspect ratios, where the seismic-force-resisting elements are positioned at a variable distance from the geometrical center in each direction. For verifying the torsional amplification factor in provisions, nonlinear reinforced concrete models with various eccentricities and aspect ratios are used in rock. The difference between the maximum displacements of the flexible edge obtained between using nonlinear static and time-history analysis is very small but the difference between the maximum torsional angles is large.

• Journal of the Korea Concrete Institute
• /
• v.17 no.6 s.90
• /
• pp.963-974
• /
• 2005

This paper presented four shear test results from experimental tests of two large prestressed concrete beams cast with high strength concrete. In particular, this experiment investigated the effects of draped strands on shear behavior of these full-scaled beams. This study indicated that the use of draped strands increased the ultimate shear capacity as well as the web-shear cracking load. The test results also showed that draped strands reduced strand slip at ends of beams, which represented that these strands were effective to relieve the anchorage stresses. The test results were compared to predictions by two major codes; ACI 318-02 Building Code and AASHTO LRFD(2002). The shear design provisions in these codes provided conservative results on the shear strengths of all test specimens with reasonable margins of safety, and these provisions were particularly more conservative for test specimens having draped strands.