Development of wood structural elements for fire resistant buildings

2018 ◽  
Vol 9 (2) ◽  
pp. 126-137
Author(s):  
Hirokazu Ohashi ◽  
Shinya Igarashi ◽  
Tsutomu Nagaoka
Keyword(s):  
Fire Resistance ◽  
Urban Areas ◽  
Research Work ◽  
Structural Elements ◽  
Wood Structures ◽  
Load Bearing ◽  
Content Type ◽  
Glued Laminated Timber ◽  
Japanese Law ◽  
Bearing Part

Purpose As forestry contributes to the reduction of greenhouse gases by CO2 fixation, in recent years, use of wood in buildings has attracted all over the world more attention. However, construction of large wood structures is almost inexistent within urban areas in Japan. This is due to the Japanese law on fire protection of wood buildings in cities, which is considered very strict with severe requirements. This paper aims to present a research work relative to the development of one-hour fire-resistant wood structural elements for buildings in cities. The developed elements are composed of three layers made of laminated timber. Design/methodology/approach These wood structural elements, made of glued laminated timber with self-charring-stop, have sufficient fire resistance during and after a fire and comply with the strict Japanese standard for wood structural elements, which stipulates that such elements have to withstand the whole dead-load of concerned buildings after fire. To comply with such requirements, new elements of glued laminated timber with self-charring-stop layer were developed, and their performance was confirmed. Several fire-resistant tests conducted on columns, beams, column-beam joints, connections between beams and walls and beams with holes were carried out. Findings All tests proved that the elements have sufficient fire resistance. No damage was found out at the load-bearing part of the elements after testing. As the developed elements have two layers protecting the load-bearing part, the temperature in the load-bearing part could be retained below 260°C (carbonization temperature) and provide the elements with a sufficient fire resistance for 1 h. Practical implications These wood structural elements have already been applied in six projects, where large-size wooden buildings were constructed in urban areas in Japan. Originality/value The proposed structural elements use a novel technique. Every wooden element is composed of three layers made of glued laminated timber. The elements have a typical performance of self-charring-stop after fire without need for water of firefighters. More technologies related to these elements, including column-beam joints and beams with holes and effect of crack, were also developed to design and construct safe wooden buildings.

scholarly journals INFLUENCE OF WOOD DENSITY TO FIRE RESISTANCE OF THE LOAD-BEARING PART

2015 ◽  
Vol 21 (47) ◽  
pp. 151-156
Author(s):  
Hirokazu OHASHI ◽  
Tsutomu NAGAOKA ◽  
Hiroki NAGAMORI ◽  
Hiromu TAKAHASHI ◽  
Masato YAMAMOTO ◽  
...  
Keyword(s):  
Wood Density ◽  
Fire Resistance ◽  
Load Bearing ◽  
Bearing Part

Fire performance of hybrid mass timber beam-end connections with perpendicular-to-wood grain reinforcement

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Oluwamuyiwa Okunrounmu ◽  
Osama (Sam) Salem ◽  
George Hadjisophocleous
Keyword(s):  
Fire Resistance ◽  
Elevated Temperatures ◽  
Time To Failure ◽  
Rotational Behaviour ◽  
Fire Performance ◽  
Timber Beam ◽  
Content Type ◽  
Glued Laminated Timber ◽  
Wood Grain ◽  
Mass Timber

PurposeThe fire resistance of timber structures is heavily dependent on the fire behaviour of the connections between its structural elements. The experimental study presented in this paper aimed to investigate the fire performance of glued-laminated timber beam connections reinforced perpendicular-to-wood grain with self-tapping screws (STS).Design/methodology/approachTwo full-size fire experiments were conducted on glulam beam-end connections loaded in flexure bending. Two connection configurations, each utilizing four steel bolts arranged in two different patterns, were reinforced perpendicular to wood grain using STS. The bolt heads and nuts and the steel plate top and bottom edges were fire protected using wood plugs and strips, respectively. Each connection configuration was loaded to 100% of the ultimate design load of the weakest unreinforced configuration. The test assemblies were exposed to elevated temperatures that followed the CAN/ULC-S101 standard fire time–temperature curve.FindingsThe experimental results show that the influence of the STS was significant as it prevented the occurrence of wood splitting and row shear-out and as a result, increased the fire resistance time of the connections. The time to failure of both connection configurations exceeded the minimum fire resistance rating specified as 45 min for combustible construction in applicable building codes.Originality/valueThe experimental data show the effectiveness of a simple fire protection system (i.e. wood plugs and strips) along with the utilization of STS on the rotational behaviour, charring rate, fire resistance time and failure mode of the proposed hybrid mass timber beam-end connection configurations.

Fire performance, including the cooling phase, of structural glued laminated timber beams

2016 ◽  
Vol 7 (4) ◽  
pp. 349-364 ◽  
Author(s):  
H. Kinjo ◽  
T. Hirashima ◽  
S. Yusa ◽  
T. Horio ◽  
T. Matsumoto
Keyword(s):  
Temperature Distribution ◽  
Maximum Load ◽  
Strength Reduction ◽  
Fire Performance ◽  
Load Bearing ◽  
Content Type ◽  
Standard Fire ◽  
Glued Laminated Timber ◽  
Charring Rate ◽  
Cooling Phase

Purpose Based on heating tests and load-bearing fire tests, this paper aims to discuss the charring rate, the temperature distribution in the section and the load-bearing capacity of structural glued laminated timber beams not only during the heating phase during a 1-h standard fire in accordance with ISO 834-1 but also during the cooling phase. Design/methodology/approach Heating tests were carried out to confirm the charring rate and the temperature distribution in the cross-section of the beams. Loading tests under fire conditions were carried out to obtain the load-deformation behavior (i.e. the stiffness, maximum load and ductility) of the beam. Findings The temperature at the centroid reached approximately 30°C after 1 h and then increased gradually until reaching 110-200°C after 4 h, during the cooling phase. The maximum load of the specimen exposed to a 1-h standard fire was reduced to approximately 30 per cent of that of the specimen at ambient temperature. The maximum load of the specimen exposed to a 1-h standard fire and 3 h of natural cooling in the furnace was reduced to approximately 14 per cent. In case of taking into consideration of the strength reduction at elevated temperature, the reduction ratio of the calculated bending resistance agreed with that of the test results during not only heating phase but also cooling phase. Originality/value The results of this study state that it is possible to study on strength reduction in cooling phase for end of heating, timber structural which has not been clarified. It is believed that it is possible to appropriately evaluate the fire performance, including the cooling phase of the timber structural.

scholarly journals The components of abstracts

2014 ◽  
Vol 115 (1/2) ◽  
pp. 15-33 ◽  
Author(s):  
Nina Jamar ◽  
Alenka Šauperl ◽  
David Bawden
Keyword(s):  
Design Methodology ◽  
Information Science ◽  
Materials Science ◽  
Research Work ◽  
Logical Structure ◽  
Background Information ◽  
Library And Information Science ◽  
Structural Elements ◽  
Content Type ◽  
The Individual

Purpose – The purpose of this study was to examine whether the logical structure of abstracts in the areas of materials science and technology and library and information science comply with the ISO 214 or IMRAD formats, while also suggesting guidelines for components of abstracts. Design/methodology/approach – In the first part of the research the components of abstracts are analysed. The results showed that not all the proposed structural elements are present in the abstracts. Therefore also the improved prototypes and recommended abstracts are developed to examine the satisfaction of readers with different forms of abstracts. According to the results of satisfaction of readers with different forms of abstracts, uniform guidelines for the components of abstracts in accordance with the IMRAD format are proposed. Findings – The introduction (I) should include three sentences of background information. The method (M) should include three sentences of method. The results (R) should include three sentences of results. The discussion (D) should include two sentences of conclusions. The conclusions should present the implications of the results on subjects that were not part of the study, suggestions for possible application of the findings, suggestions for further research work and an evaluation of the research. Originality/value – It is important to emphasize that even if the guidelines for writing abstracts by the individual journal exist, authors do not always take them into account. Therefore, it is important that the abstracts that are actually published in journals were analysed. It is also important that the opinion of researchers was taken into account.

Functionally Layered Thin Slabs Made from UHPC and ECC Composites

2017 ◽  
Vol 259 ◽  
pp. 90-96
Author(s):  
Milan Rydval ◽  
David Čítek ◽  
Jiří Kolísko ◽  
Šárka Nenadálová ◽  
Tomáš Bittner
Keyword(s):  
Tensile Strength ◽  
Deformation Modulus ◽  
Steel Fibers ◽  
Modulus Of Rupture ◽  
High Ductility ◽  
Structural Elements ◽  
Thin Slab ◽  
Load Bearing ◽  
Lower Tensile Strength ◽  
Bearing Part

Corrosion of short steel fibers is one of the limit factors for using cement based UHPC material like an architectural concrete. The steel fibers corrosion is undesirable effect. PVA fibers and TRC reinforcement are nowadays used for facade elements. Structural elements reinforced by non-conventional reinforcement have lower tensile strength, also modulus of rupture is lower, due to low tensile strengths and deformation modulus of PVA and TRC. The tensile strength is determined by properties of mixture design. The potential of functionally layered thin slabs consist on the high ductility and tensile strength of UHPC matrix reinforced by short steel fibers. The load bearing part of functionally layered slabs is made by UHPC reinforced by steel fibers and the covering part is made by ECC reinforced by PVA fibers. Ductile and durable elements should be prepared by acceptable ratio between load bearing part and covering part of functionally layered thin slab. Functionally layered slabs should be used for architectural facade elements.

scholarly journals Fire resistance of extruded hollow-core slabs

2017 ◽  
Vol 8 (3) ◽  
pp. 324-336 ◽  
Author(s):  
Kristian Hertz ◽  
Luisa Giuliani ◽  
Lars Schiøtt Sørensen
Keyword(s):  
Bearing Capacity ◽  
Fire Resistance ◽  
Hollow Core ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Content Type ◽  
Standard Fire ◽  
Comprehensive Test ◽  
Building Components ◽  
First Time

Purpose Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found in most national building regulations. The paper aims to present a detailed analysis of the mechanisms responsible for the loss of load-bearing capacity of hollow-core slabs when exposed to fire. Design/methodology/approach Furthermore, it compares theoretical calculation and assessment according to the structural codes with data derived from a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Findings Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. Originality value For the first time, the mechanisms responsible for loss of load-bearing capacity are identified, and test results and calculation approach are for the first time applied in accordance with each other for assessment of fire resistance of the structure.

Deflection behavior and load-bearing period of structural glued laminated timber beams in fire including cooling phase

2018 ◽  
Vol 9 (4) ◽  
pp. 287-299
Author(s):  
Hitoshi Kinjo ◽  
Yusuke Katakura ◽  
Takeo Hirashima ◽  
Shuitsu Yusa ◽  
Kiyoshi Saito
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Shear Failure ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Content Type ◽  
Glued Laminated Timber ◽  
Cooling Phase ◽  
Timber Beams

Purpose This paper aims to discuss the fire performance of glulam timber beams based on their deflection behavior and load-bearing period, which were obtained from load-bearing fire tests under constant load conditions. Design/methodology/approach In this report, the fire performance, primarily deflection behavior and load-bearing period of glued laminated (glulam) timber beams will be discussed from the standpoint of load-bearing fire tests conducted during the cooling phase under constant load conditions. Then, based on the charring depth and the per section temperature transformation obtained from loading test results, the load-bearing capacity of the glulam timber beams will be discussed using the effective section method and the strength reduction factor, which will be calculated in accordance with the European standards for the design of timber structures (Eurocode 5). Findings In the cooling phase, the charring rate is decreases. However, as the temperature in the cross section rises, the deflection is increases. The failure mode was bending failure because of tensile failure of the lamina at the bottom of the beam. Moreover, a gap caused by shear failure in a growth ring in the beam cross-section in the vicinity of the centroid axis was observed. Shear failure was observed up until 1 to 3 h before end of heating. The calculated shear strength far exceeded the test results. Shear strength for elevated temperature of glued laminated timber is likely to decrease than the shear strength in Eurocode 5. Originality/value Unlike other elements, a characteristic problem of timber elements is that their load-bearing capacity decreases as they are consumed in a fire, and their bearing capacities may continue to degrade even after the fuel in the room has been exhausted. Therefore, the structural fire performance of timber elements should be clarified during not only the heating phase but also the subsequent cooling phase. However, there are few reports on the load-bearing capacity of timber elements that take the cooling phase after a fire into consideration.

New mechanism for press-fit processes: preliminary analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lorenzo Fiorineschi ◽  
Luca Pugi ◽  
Federico Rotini
Keyword(s):  
Load Distribution ◽  
Preliminary Analysis ◽  
Design Methodology ◽  
Research Work ◽  
Structural Elements ◽  
End Effector ◽  
Content Type ◽  
Press Fit ◽  
Comprehensive Evaluations ◽  
Technology Processes

Purpose The purpose of this paper is to present an alternative solution for press-fit technology processes, which could improve the precision of the positioning movements and the stiffness of the structural elements. Design/methodology/approach A concept is presented and the related kinematics is described. Then, preliminary embodiment evaluations have been performed in terms of kinematics, force control and load distribution on the main structural elements. Findings Thanks to the additional leg, the proposed solution allows a preload that is capable of compensating the backlash of joints. The particular structure with four extendible legs and eight cardan joints ensures the parallelism between the ground and the plate holding the end effector, without any need of additional controls. However, it implies that the legs are not subjected to pure tension–compression stresses. Research limitations/implications This work is focused on the conceptual phase of the design process, with only preliminary embodiment analysis that paves the way for subsequent and more detailed design steps. Especially concerning the actual stiffness of the system, comprehensive evaluations could be performed only after the identification of the particular parts/devices used to implement the main functional elements. Originality/value To the best of the authors’ knowledge, this is the first research work that comprehensively describes and analyzes the considered kinematics, within a real industrial application context.

Using the private finance initiative for energy efficiency projects at the urban scale

2016 ◽  
Vol 10 (1) ◽  
pp. 99-117 ◽  
Author(s):  
Alberto De Marco ◽  
Giulio Mangano ◽  
Fania Valeria Michelucci ◽  
Giovanni Zenezini
Keyword(s):  
Energy Efficiency ◽  
Urban Areas ◽  
Light Emitting Diode ◽  
Project Finance ◽  
Private Finance Initiative ◽  
Content Type ◽  
Light Emitting ◽  
Alternate Forms ◽  
Private Investors

Purpose – The purpose of this paper is to suggest the usage of the project finance (PF) scheme as a suitable mechanism to fund energy efficiency projects at the urban scale and present its advantages and adoption barriers. Design/methodology/approach – A case study is developed to renew the traffic lighting system of an Italian town via replacement of the old lamps with new light-emitting diode (LED) technology. Several partners are involved in the case project to construct a viable PF arrangement. Findings – The case study presents the viability of the proposed PF scheme that provides for acceptable financial returns and bankability. However, it also shows that the need for short concession periods may call for a public contribution to the initial funding to make the project more attractive to private investors. Practical implications – This case study is a useful guideline for governments and promoters to using the PF arrangement to fund energy efficiency investments in urban settings. It helps designing an appropriate PF scheme and understanding the advantages of PF to reduce risk and, consequently, increase the debt leverage and profitability of energy efficiency projects. Originality/value – This paper contributes to bridging the gap about the lack of works addressing the implementation of the PF mechanism in the energy efficiency sector in urban areas. The importance of this paper is also associated with the shortage of traditional public finance faced by many cities that forces to seek for alternate forms of financing.

Loan officer rotation and credit access: evidence from Madagascar

2019 ◽  
Vol 80 (1) ◽  
pp. 51-67
Author(s):  
Yaw Sarfo ◽  
Oliver Musshoff ◽  
Ron Weber
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Frequency Effect ◽  
Content Type ◽  
Credit Access ◽  
Loan Officer ◽  
Microfinance Institution ◽  
Lending Decisions ◽  
Loan Officers ◽  
Loan Approval

Purpose With exclusive data from a commercial microfinance institution (MFI) in Madagascar, the purpose of this paper is to investigate if loan officer rotation (change of loan officer) has an effect on credit access (loan approval) in rural and in urban areas. The authors further analyze how the frequency of loan officer rotation affects credit access in rural and in urban areas. Design/methodology/approach The authors apply propensity score matching to compare credit access between loan applicants who experienced loan officer rotation and loan applicants who experienced no loan officer rotation in rural and in urban areas. Findings Results show that loan officer rotation has a positive and statistically significant effect on credit access. The authors observe further that loan officer rotation has a different effect on credit access in rural and in urban areas. Whilst rural loan applicants who experienced loan officer rotation are more likely to have credit access, urban loan applicants show no statistically significant effect of loan officer rotation on credit access. For the frequency effect on credit access, the authors observe that one loan officer rotation has a positive and statistically significant effect on credit access whereas results are mixed for two loan officer rotations. Research limitations/implications Even though the authors can show that loan officer rotation can improve credit access to loan applicants, especially in rural areas, the conditions in Madagascar are unique. Therefore, results need to be verified in other countries and institutional contexts. Practical implications From the perspective of MFI, the authors recommend that the management of MFI needs to provide better tools to loan officers to improve on the evaluation of agricultural loan products or standardize the assessment of agricultural loan products to improve on lending decisions. Further, if applicable, the authors recommend that MFI should consider using credit worthiness assessment procedures which rely less on loan officer’s judgment for loan evaluation, such as automated systems. From the perspective of loan applicants, the authors recommend that loan applicants should request for a change of loan officer if they experience successive loan applications rejection. Originality/value To the authors’ knowledge, this paper is the first to provide empirical evidence on the effect and frequency of loan officer rotation on credit access in Sub-Sahara Africa, and Madagascar, in particular.

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