• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.137-154
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• 2019

Singapore has seen a phenomenal and an unprecedented transformation from a swampland to a high density urban environment since its independence in 1965, made possible largely and single-handedly by the sustained efforts of its government. Indeed, urban space is a key vehicle for achieving urban social, environmental, economic, and cultural sustainability. The dense urban context in Singapore has seen an emergence and increase in elevated spaces in the form of sky-gardens, sky-bridges and sky-courts in a range of building types, seemingly seeking to tie together the different horizontal and vertical components of the city. This paper, therefore, examines the effectiveness of elevated urban spaces and pedestrian networks in Singapore and their ability to contribute to the horizontal to vertical transitions, and consequently to the urban vitality and accessibility. It does this through the analysis of two key developments: Marina Bay Sands and the Jurong Gateway. In particular, it considers the implications of certain constraints placed on urban spaces by their inherent location at height, in addition to the familiar privatization of public spaces, over-management of spaces, and their somewhat utilitarian characteristics. The paper argues that some of these issues may pose detrimental effects on the publicness of these spaces that in turn may lead to such spaces being underused and therefore adding redundancies and further stress to Singapore's urban land. Finally, the paper outlines key strategies that may help overcome the aforementioned issues, including the disjuncture associated with elevated spaces such that they may become a seamless extension of the urban spaces on ground.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.71-80
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• 2007

Because of the characteristics relating to high tensile ductility, High Performance Fiber Reinforced Cementitious Composites (HPFRCC) are studied to be adopted in repair and retrofit of buildings. A series of three shear wall specimens was tested under constant axial stress and reversed cyclic lateral loading in order to evaluate the seismic retrofit that had been proposed for the shear wall with the opening. The retrofit involved the use of newly developed ECC and MDF(Macro Defect Free), both of which are sprayed through the high pressure pump, over the entire face of the wall. The results indicate that two difference types of retrofitting strategy make the different effects of a rise in the strength and ductility of each specimen.

• Fire Science and Engineering
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• v.30 no.2
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• pp.1-6
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• 2016

We are living in the 21st century, a new era of high-technology. Due to movements in population towards certain preferred areas, caused by material and technological advancement, growth has occurredn beyond the metropolis, leading to the development of the so-calleda "megalopolis." This development has changed the culture of housing, notably the characteristics of high-rise buildings, and underground facilities (such as subways and shopping centers), and has generally enlarged the scale of the facilities. Due to the increase in the number of single-family households, - notably ones including only the nuclear family, there has been a growing overpopulation problem, with apartments and urban housing developments expanding at rates beyond institutional safety regulations. In this study, we analyze the phenomenon of fire spreading in apartment buildings through actual apartment fire case studies, including that of the MunjonPonpuri apartment building. It was found that the speed at which the fire spreads is lower in apartments without than in those with an extended balcony. Based on the findings from case studies and the test results, we propose a series of safety countermeasures and responses for apartment fires.

• Earthquakes and Structures
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• v.14 no.4
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• pp.349-360
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• 2018

Reinforced concrete (RC) moment frames supported on two ground levels have been widely constructed in mountainous areas with medium to high seismicity in China. In order to investigate the seismic collapse behavior and risk, a scaled frame model was tested under constant axial load and reversed cyclic lateral load. Test results show that the failure can be induced by the development of story yielding at the first story above the upper ground. The strong column and weak beam mechanism can be well realized at stories below the upper ground. Numerical analysis model was developed and calibrated with the test results. Three pairs of six case study buildings considering various structural configurations were designed and analyzed, showing similar dynamic characteristics between frames on two ground levels and flat ground of each pair. Incremental dynamic analyses (IDA) were then conducted to obtain the seismic collapse fragility curves and collapse margin ratios of nine analysis cases designated based on the case study buildings, considering amplification of earthquake effect and strengthening measures. Analysis results indicate that the seismic collapse safety is mainly determined by the stories above the upper ground. The most probable collapse mechanism may be induced by the story yielding of the bottom story on the upper ground level. The use of tie beam and column strengthening can effectively enhance the seismic collapse safety of frames on two ground levels.

• International Journal of High-Rise Buildings
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• v.6 no.2
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• pp.149-163
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• 2017

With the intensification of urban development in Chinese cities, mixed land use in urban centers extends vertically into 3-D and expands its scale from a single building to commercial clusters. The multi-level pedestrian system in city centers also changed its role from one of traffic isolation to spatial integration, where transit nodes, street sidewalks, squares, building entrances, atriums, and corridors are interconnected, both horizontally and vertically, into a whole spatial system, within which pedestrian flows are guided and shopping facilities are arranged. This paper uses spatial configuration analysis of space syntax to examine the impacts of spatial patterns on movement distribution and the business performance of tenant mix in the multi-level commercial system of the Nanshan Commercial Cultural District in Shenzhen, China. The key objective is to better understand the interactions between the socio-economic variables and spatial design parameters of a shopping complex. The research findings point to the importance of multiplicity between syntactic variables and other spatial variables in influencing the pedestrian flows, business performance and tenant mix in highly complex commercial systems. Particularly noteworthy is the relationship between spatial accessibility measures and the location of escalators, and the ways in which individual commercial buildings are embedded into the overall spatial system. The study suggests that this may lead to the preliminary identification of the spatial qualities of effective vertical extensions of mixed land use in a high-density urban settings.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.30-38
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• 2014

Achieving high productivity and constructability are very important issues in construction industry. Study on constructability have been conducted actively, and many researches referred that improving constructability can enhance cost, quality, schedule, productivity and so on. However, there are lack of quantitative analysis, since most studies have proved correlation between productivity and constructability using questionaries and by case studies. Also, researches are mostly about specific detail scope of work to improve constructability, thus it is hard to apply constructability factors on various work in construction. In this paper, will deduct general factors affecting on constructability and evaluate effects of factors affecting on each work. Furthermore this paper will verify impact of factors affecting on productivity by multi regression anlaysis using actual data sets of high-rise building construction site.

• International Journal of High-Rise Buildings
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• v.12 no.1
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• pp.93-105
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• 2023

Seismic isolation and vibration control techniques have been developed and put into practical use by challenging researchers and engineers worldwide since the latter half of the 20th century, and after more than 40 years, they are now used in thousands of buildings, private residences, highways in many seismic areas in the world. Seismic isolation and vibration control structures can keep the structures undamaged even in a major earthquake and realize continuous occupancy. This performance has come to be recognized not only by engineers but also by ordinary people, becoming indispensable for the formation of a resilient society. However, the dynamic characteristics of seismically isolated bearings, the key elements, are highly dependent on the size effect and rate-of-loading, especially under extreme loading conditions. Therefore, confirming the actual properties and performance of these bearings with full-scale specimens under prescribed dynamic loading protocols is essential. The number of testing facilities with such capacity is still limited and even though the existing labs in the US, China, Taiwan, Italy, etc. are conducting these tests, their dynamic loading test setups are subjected to friction generated by the large vertical loads and inertial force of the heavy table which affect the accuracy of measured forces. To solve this problem, the authors have proposed a direct reaction force measuring system that can eliminate the effects of friction and inertia forces, and a seismic isolation testing facility with the proposed system (E-isolation) will be completed on March 2023 in Japan. This test facility is designed to conduct not only dynamic loading tests of seismic isolation bearings and dampers but also to perform hybrid simulations of seismically isolated structures. In this paper, design details and the realization of this system into an actual dynamic testing facility are presented and the outcomes are discussed.

• Fire Science and Engineering
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• v.22 no.3
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• pp.194-200
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• 2008

In order to design and operate successfully the pressure differential system for smoke control which uses difference of pressure between compartments of building, architectural factors affecting the pressure field of building should be examined and the stack effect is one of the important factors. The field experiments on pressure field in two buildings of 21 stories and 31 stories in summer and winter season with regard to on/off condition of the pressure differential system are carried out to evaluate the influence of stack effect to evacuation and smoke management of high-rise building. In winter season when the stack effect increases, as the pressure differential system starts to operate, the pressure in upper stair rises largely due to the combination effect of the air infiltration from lobby to stair and the stack effect.

• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.9-25
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• 2015

Field measurements of various structures have been conducted for many purposes. Measurement data obtained by field measurement is very useful to determine vibration characteristics including dynamic characteristics such as the damping ratio, natural frequency, and mode shape of a structure. In addition, results of field measurements and modal identification can be used for modal updating of FEM analysis, for checking the efficiency of damping devices and so on. This paper shows some examples of field measurements and modal identification for structural health monitoring. As the first example, changes of dynamic characteristics of a 15-story office building in four construction stages from the foundation stage to completion are described. The dynamic characteristics of each construction stage were modeled as accurately as possible by FEM, and the stiffness of the main structural frame was evaluated and the FEM results were compared with measurements performed on non-load-bearing elements. Simple FEM modal updating was also applied. As the next example, full-scale measurements were also carried out on a high-rise chimney, and the efficiency of the tuned mass damper was investigated by using two kinds of modal identification techniques. Good correspondence was shown with vibration characteristics obtained by the 2DOF-RD technique and the Frequency Domain Decomposition method. As the last example, the wind-induced response using RTK-GPS and the feasibility of hybrid use of FEM analysis and RTK-GPS for confirming the integrity of structures during strong typhoons were shown. The member stresses obtained by hybrid use of FEM analysis and RTK-GPS were close to the member stresses measured by strain gauges.

• Korean Journal of Construction Engineering and Management
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• v.4 no.4 s.16
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• pp.182-191
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• 2003

The material lift-up and procurement management for high-rise buildings is complex and critical key to the success of projects. It has been hardly managed by the heuristic or rule-of-thumb techniques which are adapted in usual construction building sites. Especially in downtown high-rise residential building project sites, the limit of heuristic management techniques is critical. It has space constraint for materials loading and site transportation especially in finish work phases in which construction period diverse work trades struggle for their own material and manpower transportation. Hence, it is essential to adapt JIT(Just-In-Time) concept in these particular types of building construction project sites. According to the analysis of the case project sites, the communication and flow of relevant information regarding material lift-up and transportation in project sites is the key factor for successful performance. Therefore, this study analyzes the flow and site transportation of the key materials and provides the system, PLUTO(Procurement & Lift-Up for material Transport Optimizing system). This study also applies the system in the case site and verifies the model validation in actual project.