The competitive trends of the world market have long been forcing structural engineers to develop minimum weight and labour cost solutions. A direct consequence of this new design trend has been a considerable increas...The competitive trends of the world market have long been forcing structural engineers to develop minimum weight and labour cost solutions. A direct consequence of this new design trend has been a considerable increase in problems related to undesired floor vibrations. For this reason, structural floor systems can become vulnerable to excessive vibrations that are produced by, for example, impacts due to mechanical equipment （e.g., rotating machinery）. This study investigates the dynamic behaviour of a production platform constructed of steel and located in the Santos Basin （Merluza field）, Sao Paulo/SP, Brazil, when subjected to impacts produced by mechanical equipment （rotating machinery）. The structural model consists of two steel decks with a total area of 1,915 m^2 （upper deck： 445 m^2, lower deck： 1,470 m^2） and supported by piles. A numerical analysis is performed to assess the dynamic impacts on the deck structure originating from the electrical generators and compressors. Based on the peak acceleration values obtained for the structure steady-state response, it is possible to evaluate the structural model performance in terms of human comfort, the maximum tolerances of the mechanical equipment and the vibration serviceability limit states of the structure.展开更多
The current steel-concrete composite floors design might be susceptible to the resonance phenomenon, causing undesirable vibrations in the frequency range that is the most noticeable to humans, i.e., 4 Hz to 8 Hz. Thi...The current steel-concrete composite floors design might be susceptible to the resonance phenomenon, causing undesirable vibrations in the frequency range that is the most noticeable to humans, i.e., 4 Hz to 8 Hz. This way, the main objective of this work is to investigate the dynamic structural behaviour of a steel-concrete composite multi-storey building when subjected to human rhythmic activities （aerobics）. The studied structural model represents a typical interior floor bay of a commercial building used for gym and is composed by three floor levels spanning 20 m by 20 m, with a total area of 3×400 m2. An extensive parametric study was developed aiming to obtain the peak accelerations, RMS （root mean square） accelerations and VDV （vibration dose value） values, based on two different mathematical formulations. The human comfort of the building was analysed and the vibration transmissibility related to the steel columns was verified. Based on the found results, the investigated structural model presented high vibration levels that compromise the human comfort.展开更多
This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large com...This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large compressor installed in an industry for the production of air gases.The concrete slab presents a dimension of 12 m×15 m,required to support a compressor-motor assembly weighting 1,900 kN and positioned at a height of 4m of the investigated concrete floor.In this investigation,two numerical models were developed and the difference between these models is characterized by the discretization of the support points(pre-cast concrete piles).The developed numerical model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the CSi SAP2000 V.17.2.0 software.Based on the developed analysis methodology,the dynamic structural response of the foundation system is evaluated in terms of natural frequencies,vibration modes,displacements,velocities,and accelerations.The maximum values of the dynamic response of the system are compared with the limit values recommended by standards and project recommendations,aiming a careful evaluation,regarding the performance of the structure in terms of excessive vibrations and the economic aspects involved in the design of the foundation system.Finally,the obtained results of the two developed numerical models are compared,as to evaluate if there are benefits in refining the support points modelling.展开更多
Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the...Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the asphalt production and construction, in addition to reducing greenhouse-gas emissions. This study evaluated the effects of Evotherm and RH-WMA and RAP on mixtures＇ behavior in terms of the compaction energy index （CEI）, indirect tensile strength （ITS） and resilient modulus. The results showed that warm mix additives reduced the CEI, ITS and resilient modulus; while RAP increased the corresponding values. Statistical analysis showed that mixtures incorporating Evotherm and RAP had significant effects on CEI, while the effects of RH-WMA on the corresponding value were found to be statistically insignificant. General Linear Model showed that Evotherm, RAP and RH-WMA exhibited no significant effects on the ITS and resilient modulus. The one-way analysis of variance showed that Evotherm influenced mixture behavior significantly, while RAP and RH-WMA effects were found to be statistically insignificant. Regression equations with high accuracy levels were proposed to predict CEI, ITS and resilient modulus with respect to modification of mixture variables such as mix constituents （Evotherm, RH-WMA, and RAP） and compaction temperature.展开更多
基金Acknowledgments The authors gratefully acknowledge the support for this work provided by the Brazilian Science Foundations： CAPES, CNPq and FAPERJ.
文摘The competitive trends of the world market have long been forcing structural engineers to develop minimum weight and labour cost solutions. A direct consequence of this new design trend has been a considerable increase in problems related to undesired floor vibrations. For this reason, structural floor systems can become vulnerable to excessive vibrations that are produced by, for example, impacts due to mechanical equipment （e.g., rotating machinery）. This study investigates the dynamic behaviour of a production platform constructed of steel and located in the Santos Basin （Merluza field）, Sao Paulo/SP, Brazil, when subjected to impacts produced by mechanical equipment （rotating machinery）. The structural model consists of two steel decks with a total area of 1,915 m^2 （upper deck： 445 m^2, lower deck： 1,470 m^2） and supported by piles. A numerical analysis is performed to assess the dynamic impacts on the deck structure originating from the electrical generators and compressors. Based on the peak acceleration values obtained for the structure steady-state response, it is possible to evaluate the structural model performance in terms of human comfort, the maximum tolerances of the mechanical equipment and the vibration serviceability limit states of the structure.
文摘The current steel-concrete composite floors design might be susceptible to the resonance phenomenon, causing undesirable vibrations in the frequency range that is the most noticeable to humans, i.e., 4 Hz to 8 Hz. This way, the main objective of this work is to investigate the dynamic structural behaviour of a steel-concrete composite multi-storey building when subjected to human rhythmic activities （aerobics）. The studied structural model represents a typical interior floor bay of a commercial building used for gym and is composed by three floor levels spanning 20 m by 20 m, with a total area of 3×400 m2. An extensive parametric study was developed aiming to obtain the peak accelerations, RMS （root mean square） accelerations and VDV （vibration dose value） values, based on two different mathematical formulations. The human comfort of the building was analysed and the vibration transmissibility related to the steel columns was verified. Based on the found results, the investigated structural model presented high vibration levels that compromise the human comfort.
文摘This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large compressor installed in an industry for the production of air gases.The concrete slab presents a dimension of 12 m×15 m,required to support a compressor-motor assembly weighting 1,900 kN and positioned at a height of 4m of the investigated concrete floor.In this investigation,two numerical models were developed and the difference between these models is characterized by the discretization of the support points(pre-cast concrete piles).The developed numerical model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the CSi SAP2000 V.17.2.0 software.Based on the developed analysis methodology,the dynamic structural response of the foundation system is evaluated in terms of natural frequencies,vibration modes,displacements,velocities,and accelerations.The maximum values of the dynamic response of the system are compared with the limit values recommended by standards and project recommendations,aiming a careful evaluation,regarding the performance of the structure in terms of excessive vibrations and the economic aspects involved in the design of the foundation system.Finally,the obtained results of the two developed numerical models are compared,as to evaluate if there are benefits in refining the support points modelling.
基金the Malaysian Ministry of Higher Education for funding this research through the Exploratory Research Grant Scheme (ERGS grant number 203/ PAWAM/6730111)
文摘Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the asphalt production and construction, in addition to reducing greenhouse-gas emissions. This study evaluated the effects of Evotherm and RH-WMA and RAP on mixtures＇ behavior in terms of the compaction energy index （CEI）, indirect tensile strength （ITS） and resilient modulus. The results showed that warm mix additives reduced the CEI, ITS and resilient modulus; while RAP increased the corresponding values. Statistical analysis showed that mixtures incorporating Evotherm and RAP had significant effects on CEI, while the effects of RH-WMA on the corresponding value were found to be statistically insignificant. General Linear Model showed that Evotherm, RAP and RH-WMA exhibited no significant effects on the ITS and resilient modulus. The one-way analysis of variance showed that Evotherm influenced mixture behavior significantly, while RAP and RH-WMA effects were found to be statistically insignificant. Regression equations with high accuracy levels were proposed to predict CEI, ITS and resilient modulus with respect to modification of mixture variables such as mix constituents （Evotherm, RH-WMA, and RAP） and compaction temperature.
