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CONTENTS
Volume 11, Number 6, June 2021
 


Abstract
This study represents procedures and material to improve sound transmission loss through concrete without having any significant effects on mechanical properties. To prevent noise pollution damaging effects, and for reducing the transmission of the noises from streets to residential buildings, sound absorbing materials could be effectively produced. For this purpose, a number of several mixture designs have been investigated in this study to reduce the sound transmission through concrete, including control sample and three mixtures with recycled rubber with sizes of from 1mm up to 3 mm to limit the sound transmission. The rubber is used as a replacement of 5, 10, and 15 percent of sand aggregates. First, 7, 14 and 28-day strengths of the concrete have been measured. Subsequently, the sound transmission losses through the samples have been measured at the range of 63 Hz up to 6300 Hz by using impedance tube and the transfer function. The results show specimens containing 15% fine-grained crumbs, the loss of sound transmission were up to 190%, and for samples with 15% coarse-grained rubber, the loss of sound transmission were up to 228%, respectively. It is shown that concrete with recycled rubber crumbs could effectively improve environmental noise absorption.

Key Words
concrete; recycled rubber crumbs; sound transmission loss; mix design; impedance tube

Address
Navid Chalangaran: Department of Civil Engineering, Qeshm Branch, Islamic Azad University, Qeshm, Iran
Alireza Farzampour: Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, United States
Nima Paslar: Department of Civil Engineering, Payame Noor University (PNU), P.O Box 19395-4697, Tehran, Iran
Hadi Fatemi: Department of Civil Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran

Abstract
This paper provides energy and economic analysis relevant to the cooling season in building enclosures. For a whole year, an Energy Plus thermal transfer model has been created and simulated. Simulations were made from the cities in five different areas of climate in China using weather data files. Energy savings were done from natural cold (e.g., outdoor air), and electricity reductions were performed from air-conditioning electricity devices. This research has investigated the relationship between the cost and building energy while finding a strong and positive correlation. This study has used the Artificial Intelligence (AI) model as Extreme Learning Machine (ELM) and Teaching Learning Based Optimization (TLBO) to calculate the accurate measurement. Three regression models as Pearson correlation coefficient (r), root mean square (RMSE), and coefficient of determination (R2) was used to calculate the results. Following the results of (R2) and RMSE, ELM has shown its higher performance in predicting the strength, energy, and cost of building materials. Based on the simulation results, for office buildings situated in cold areas, the energy savings resulting from phase change materials (PCM) are more prevalent. The test findings demonstrate that the energy savings from PCM applications for the cool area and hot summers and cold winter office buildings were increased. Simple payback time indicated that PCMBs in inhabited buildings could be used costeffectively in a mild temperature environment.

Key Words
sustainability; building energy optimization; economic management; soft computing

Address
Zhao Wei: School of Management, Wuhan Polytechnic University, 430023 Wuhan, China
Yousef Zandi: Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
Morteza Gholizadeh: Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
Abdellatif Selmi: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia; Ecole Nationale d'Ingénieurs deTunis (ENIT), Civil Engineering Laboratory, B.P. 37, Le belvédère1002, Tunis, Tunisia
Angel Roco-Videla: Programa Magister en Ciencias Químico-biológicas, Facultad de Ciencias de la Salud, Universidad Bernardo O'Higgins, Santiago, Chile; Departamento de Ingeniería Civil, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, Concepción, Chile
Usama Konbr: Department of Architecture, Faculty of Engineering, Tanta University, Egypt

Abstract
This paper provides an analytical model to predict the concrete contribution to shear strength of reinforced concrete (RC) beams that fail in flexure. In the RC members subjected to cyclic loading, the stiffness and hysteretic energy dissipation decreases with diagonal web cracking in the plastic hinge region. The proposed method takes into account plastic rotation in the plastic hinge region by means of critical shear crack theory. To verify the concrete contribution to shear strength predicted by the proposed method, six normal- and high-strength RC beams having various shear span-to-effective depth ratios are tested under cyclic loading. The predictions by the proposed equation and various researchers' equations are compared to the test results. It is found that the proposed method is in good agreement with the test results.

Key Words
degradation in the shear strength; seismic performance; RC beams; concrete contribution; high-strength concrete; plastic hinge rotation

Address
Cem Aydemir, Müberra Eser Aydemir: Department of Civil Engineering, İstanbul Aydin University, İstanbul, Turkey
Güray Arslan: Department of Civil Engineering, Yildiz Technical University, İstanbul, Turkey

Abstract
This research investigated the flexural strengthening of RC beams using Aluminum plates (AP). An experimental program including 8 RC beams were carried out. The width and depth of the beam were 150 and 300 mm respectively while the effective span of the beam was 1560 mm. The tensile reinforcement ratios of the beams were 0.38 and 0.548%. The external APs ratios (the cross sectional area of AP to the beam cross sectional area) were 0.10, 0.37 and 0.74% while the AP length to the beam length was 0.93. A Finite element analysis (FEA) was investigated to study many variables that influenced on the ultimate load and the behavior of the AP-strengthened beams such as AP length, using shear connectors, using various techniques of the end anchorages and using anchored/unanchored U-shaped APs. It was noticed that the improvement ratios of the ultimate load and the ductility of strengthened beams with tensile reinforcement ratio of 0.38% was better than the beams with tensile reinforcement ratio of 0.548%. The AP length to the beam span ratio had a significant effect on the ultimate load, the ductility and the failure mode of the beams. The ultimate deflection and the ultimate load of the AP strengthened beams that used shear connectors increased by 165 and 54 % respectively compared to the beam without shear connectors. Using U-shaped AP jacket accompanied with end anchorages enhanced the ultimate load by 109%. The ultimate load of the beams with bolted U-shaped AP jacket increased by 128%.

Key Words
flexural strengthening; RC beams; experimental work; aluminum plates; FEA; ultimate load; ductility; end anchorages; connectors

Address
Galal Elsamak and Sabry Fayed: Department of Civil Engineering, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt

Abstract
Freeze and thaw phenomena in cold regions are the main cause of severe damage to concrete structures. Alkaliactivated slag repair mortars, which are introduced as a suitable material for the replacement of Portland cement, can be used as the protective coating for these damaged structures. The mechanical properties and durability of this coating layer should be studied. In this study, the mechanical properties and durability of alkali-activated slag repair mortars with silica fume (SF) participation as inorganic additives against freeze-thaw and salt scaling attacks have been investigated. In order to evaluate the effects of alkaline activators type, the ratio of these solutions to Pozzolan (Pozz), and the use of SF as a substitute base material, these three factors were considered as the main variables to produce 12 alkali-activated slag mortar mixtures. To investigate their mechanical properties, compressive strength, tensile adhesion strength, and drying shrinkage tests were conducted. Also, mortar specimen length change, compressive strength loss, weight loss, and dynamic elastic modulus were measured to evaluate the durability features against freeze-thaw and salt scaling attacks. According to the results, in addition to higher compressive strength and adhesion resistance of alkali-activated slag repair mortars, these mortars showed at least 30% better durability against freeze-thaw and salt scaling attacks than cement-based repair mortar. Also, alkali-activated slag mixtures containing potassium hydroxide, alkaline solution (AS) to Pozz ratio of 0.7, and SF had the best mechanical properties and frost resistance among all mixtures.

Key Words
alkali-activated slag repair mortar; silica fume; durability; freeze-thaw resistance; salt scaling attack

Address
Faramarz Moodi, Sepehr Norouzi and Pooria Dashti: Faculty of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran

Abstract
Freeze and thaw phenomena in cold regions are the main cause of severe damage to concrete structures. Alkaliactivated slag repair mortars, which are introduced as a suitable material for the replacement of Portland cement, can be used as the protective coating for these damaged structures. The mechanical properties and durability of this coating layer should be studied. In this study, the mechanical properties and durability of alkali-activated slag repair mortars with silica fume (SF) participation as inorganic additives against freeze-thaw and salt scaling attacks have been investigated. In order to evaluate the effects of alkaline activators type, the ratio of these solutions to Pozzolan (Pozz), and the use of SF as a substitute base material, these three factors were considered as the main variables to produce 12 alkali-activated slag mortar mixtures. To investigate their mechanical properties, compressive strength, tensile adhesion strength, and drying shrinkage tests were conducted. Also, mortar specimen length change, compressive strength loss, weight loss, and dynamic elastic modulus were measured to evaluate the durability features against freeze-thaw and salt scaling attacks. According to the results, in addition to higher compressive strength and adhesion resistance of alkali-activated slag repair mortars, these mortars showed at least 30% better durability against freeze-thaw and salt scaling attacks than cement-based repair mortar. Also, alkali-activated slag mixtures containing potassium hydroxide, alkaline solution (AS) to Pozz ratio of 0.7, and SF had the best mechanical properties and frost resistance among all mixtures.

Key Words
pozzolanic concrete; ash; iron slag; compressive strength; wind ash; steel slag pozzolans; water-cement based polymers

Address
Ting Cai: School of Information Engineering, Xizang Minzu University, Xianyang, 712082, Shaanxi, China
Yousef Zandi: Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
Alireza Sadighi Agdas: Ghateh Gostar Novin Company, Tabriz, Iran
Abdellatif Selmi: Department of Civil Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Al‑Kharj 11942, Saudi Arabia; Civil Engineering Laboratory, Ecole Nationale D'Ingénieurs deTunis (ENIT), B.P. 37, Lbelvédère1002, Tunis, Tunisia
Alibek Issakhov: Al-Farabi Kazakh National University, Almaty, Kazakhstan; Kazakh-British Technical University, Almaty, Kazakhstan
Angel Roco-Videla: Programa Magister en Ciencias Químico-Biológicas, Facultad de Ciencias de la Salud, Universidad Bernardo O'Higgins, Santiago, Chile; Departamento de Ingeniería Civil, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, Concepción, Chile

Abstract
This paper deals with the mathematical modelling and numerical study for buckling analysis in concrete beams containing carbon nanotubes (CNTs). In order to modelling the concrete structure, Euler-Bernoulli beam is utilized. For assuming the influences of CNTs in the concrete beam and the agglomeration of CNTs, the Mori-Tanaka model is utilized. The principle of Hamilton is utilized for calculating the final equations and solved by two procedures of differential quadrature (DQ) and analytical method of Navier. The comparison of obtained results from DQ and Navier methods are shown the validation of this work. In addition, the outcomes are compared with other papers in the literature. The influences of boundary condition, CNT volume fraction, CNT agglomeration, length to thickness ratio and mode number are shown on the normalized buckling load. The outcome presents with enhancing the volume fraction of reinforcing the beam by nanoparticles, the buckling load of structure is improved. Indeed, the agglomeration of CNTs can reduces the buckling load and stability of beam.

Key Words
buckling; concrete beam; CNTs; numerical method; agglomeration

Address
Shahram Ghaedi Faramoushjan: Department of Mining Engineering, Sirjan Branch, Islamic Azad University, Sirjan, Iran
Hossein Jalalifar: Department of Petroleum Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
Reza Kolahchi: Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam

Abstract
Nitrogen and phosphorus contained in storm water runoff contaminate both surface and ground waters, causing problems for natural aquatic systems and human health. Pervious concrete particularly developed for pollutant removal might be a novel notion to remove nitrate from runoff. In this research, three aggregates were used in pervious concrete as Nano silica, perlite (Pe) and zeolite (Z) which are able to adsorb pollutants. The water absorption, compressive strength, porosity, permeability of aggregate and nitrate removal of concrete samples were evaluated in tests. While adding Nano silica, perlite and zeolite, experiments have shown that addition of fine grains enhances runoff efficiency and compressive strength, but reduces permeability and porosity. Both adsorbents improved the runoff quality while increasing the additives' ratio. The mechanical properties were density of 879 (Kg/m3), permeability of 1.06 (cm/s), the void rate of 19.7(%), compressive strength of 3.6 (MPa), and nitrate removal of about 75%. While adding perlite with the highest (40%) water absorption, the results showed no reactivity of aggregates in terms of alkali-silica reaction. Considering the Permeability tests, perlite has the minimum (1.4 cm/s) permeability, and then adding perlite to previous concrete brought the nitrate absorption capacity about 70 ml/g (60%). The best results belonged to samples containing zeolite treatments (with 15% adsorbent and 0, 10, 20% fine-grains) with a maximum pollution decline and improved Chemical Oxygen Demand (COD) (87.1, 82.6 and 89.3%), Biochemical oxygen demand (BOD) (88.1, 87.3 and 90.7%) and Total suspended solids (TSS) (75.8, 79.1 and 84.6%). Thus, zeolite has shown effective mechanical characteristics and runoff quality, while perlite and Nano silica has shown a poor and moderate performance among the adsorbents in all tests, respectively.

Key Words
pervious concrete; nitrate removal; mix design; nano-silica; perlite with pervious concrete for nitrate removal from the contaminated water

Address
Seyed Azim Hosseini and Ali Toghroli: Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran


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