钢筋混凝土墙与陶粒混凝土砌块填充墙防裂缝措施

1工程概述 美利新世界住宅小区E-12^#、E-13^#楼工程建筑面积约1．2万m^2，结构形式为钢筋混凝土短肢剪力墙结构。地上六层，三室两厅两卫。墙体设计内外墙均为200mm厚，内墙为填充墙，填充墙采用200mm厚陶粒混凝土空心砌块。陶粒混凝土空心砌块已不是新型墙体材料，此种砌块填充墙墙体抹灰出现墙面裂缝早已成为一种质量通病。考虑此工程墙体情况，处理不好钢筋混凝土墙与陶粒混凝土空心砌块墙体的衔接，将来出现墙体裂缝会给装修及工程竣工后的维修带来困难。     

防止和减轻混凝土空心砌块墙体裂缝的一些措施

1　前言在国内很多地区混凝土小型空心砌块已成为取代实心粘土砖的主导墙体材料。城市中砌块建筑可分为三大类 :一类是用混凝土小型空心砌块建造的 6～ 7层多层砌块住宅 ;第二类是用高强砌块、配筋砌体建造的高层小砌块住宅 ;第三类是用各种轻质砌块砌筑框架结构的填充墙。由于混凝土小型空心砌块墙体干缩率较砖墙体大 ,抗剪强度较砖砌体低 ,因而导致混凝土小型空心砌块墙体更容易开裂。2　混凝土小型空心砌块墙体的裂缝形态混凝土小型空心砌块墙体裂缝按其形成的原因可分为两大类 :①变形裂缝 ,包括温度裂缝、干缩裂缝 ;②受力裂缝 (主要是…     

框架填充墙裂缝的施工预防控制措施

(1)施工时砌块应适当浇水润湿,砂浆饱满,灰缝均匀.砌块过干,砂浆不饱满,灰缝不均匀,影响填充墙的整体性,减小粘结强度和墙体的抗剪等能力,在一定条件下更容易产生一些干缩裂缝、温度裂缝、受力裂缝.     

加气混凝土砌块填充墙抹灰裂缝的预防措施

<正>本方案主要针对在加气混凝土砌块填充墙墙面抹灰时出现裂缝的现象,提出在砌筑加气块和后期抹灰时采取必要、有效的预控措施。一、裂缝产生部位(1)混凝土柱(墙)与填充墙交接部位。(2)填充墙顶部与梁底。(3)墙体上所开线槽处出现裂缝。(4)墙面大面积范围出现的不规则的干缩裂缝等。(5)门窗两侧出现的裂缝。     

陶粒混凝土砌块填充墙的防裂措施

填充墙砌体是指在结构中起围护和分隔作用的墙体,不传递上部荷载。根据调查,很多使用陶粒混凝土砌块墙体都存在裂缝现象,主要是墙体与梁柱连接处出现裂缝。对预防裂缝来说,采取的主要防裂措施如下:填充墙砌筑时,砌块应靠紧墙壁或柱壁,砂浆要饱满并控制日砌高度,砌至接近梁板底时,应留一定空隙,待砌完并至少间隔7天后,再将其补砌挤紧。     

混凝土空心砌块填充墙施工应注意的问题

通过对两幢厂房中混凝土空心砌块填充墙体裂缝的原因分析,总结出目前混凝土空心砌块填充墙存在的一些加剧墙体裂缝扩展的施工因素,并提出解决此类施工问题的方法。     

常用砌块填充墙变形分析及裂缝机理研究

蒸压粉煤灰砌块、蒸压加气混凝土砌块和普通混凝土小型砌块是应用广泛的填充墙体材料,这类砌块填充墙体很容易出现裂缝,是目前建筑工程质量主要质量通病之一。本文通过对这三种砌块墙体的变形监测,研究了墙体变形规律,提出了相应的砌块墙体裂缝控制措施。     

建筑加气混凝土砌块墙体裂缝控制

建筑工程中存在常见的填充墙墙体裂缝等通病问题,结合多年施工技术经验,从多方面因素探讨其填充墙墙体裂缝原因,提出了具体防治措施,以提高填充墙的施工质量,促进轻质砌块、混凝土空心砌块等的发展。     

钢筋混凝土框架结构填充墙裂缝的成因与治理

针对加气混凝土砌块和炉渣空心砌块填充墙易于开裂的现状,分析了填充墙墙体开裂的原因,详细地阐述了填充墙墙体裂缝的防治措施,同时对填充墙抹灰裂缝的防治进行了介绍,以减少或杜绝框架结构填充墙的裂缝。     

防治蒸压加气混凝土砌块墙体裂缝、渗漏的施工技术措施

主要分析蒸压加气混凝土砌块墙体结构裂缝和非结构裂缝的产生的情况,介绍抹压工艺在蒸压加气混凝土砌块墙体结构裂缝和聚丙烯纤维抹灰砂浆在蒸压加气混凝土砌块墙体非结构性裂缝的防治作用,保证了蒸压加气混凝土砌块墙体的有效抗裂性,提高了墙体的抗渗效果。     

Critical Factors in Financing and Management of Light Rail Transit Systems： Delphi Methodology Approach

In recent years, a large number of LRT （light rail transit） networks and tramways have been built in Spain using the tender system. The rhythm of construction has been such that very few analyses have been carried out and those that have were only partially done because the main participants involved had ulterior motives which impeded their having a critical and independent opinion of the projects carried out. Within this framework, the Delphi methodology presents itself as a very useful instrument, as the intrinsic advantages that it has added to the characteristic that the experts who participate in the project can remain anonymous without detracting value from the conclusions obtained as these are grouped together according to their worth.     

Unanticipated Bond Failure over Supporting Band Beams in Grouted Post-Tensioned Slab Tendons with Little or No Initial Prestress

After grouting the ducts in a large band beam and one-way slab post-tensioned floor system in a large shopping mall （in excess of 1.5 km2 in plan）, doubts arose concerning the level of initial prestress and the strength and serviceability of the slabs was questioned. To assess the strength of the slabs, it was assumed, as a worst case scenario, that some spans may have been constructed with zero initial prestress. Load tests on prototype specimens, with similar dimensions and reinforcement quantities as the floor slabs, were performed to assess the stress development in initially unstressed, but fully grouted, tendons. Unexpected bond failures occurred at the junctions of slab and band beam where the abrupt change in section depth caused a sudden change in tendon stress. The maximum stress that was developed in the initially unstressed tendons at these locations was about 60% of the strength of the tendons.     

Flexible Pavement Design Simulation Using Mechanistic-Empirical Pavement Design Guide

The KDOT （Kansas Department of Transportation） is currently adopting MEPDG （mechanistic-empirical pavement design guide） to replace the 1993 AASHTO （American Association of State Highway and Transportation Officials） design method. The main objective of this study was to compare flexible pavement design using 1993 AASHTO design guide and MEPDG. Five newly built Superior PERforming Asphalt PAVEments （Superpave）, designed using the 1993 AASHTO Design Guide, were selected as test sections for the design simulation study. Deflection data were collected approximately 8 to 10 weeks after construction using FWD （falling weight deflectometer）. The FWD deflection data were used to back-calculate the pavement layer moduli using three different back-calculation programs. The existing pavement structures were analyzed for a 10-year analysis period. The maximum numbers of years the existing pavement structures will be in a serviceable condition as well as the minimum thicknesses of different layers to serve for 10-years were also determined. Effects of changing subgrade modulus, target distress, and reliability were also investigated. The MEPDG design analysis shows that the 1993 AASHTO Guide-designed flexible pavements do not show the distresses currently observed in Kansas for the 10-year design period. The MEPDG design simulation shows that the thinner the pavement sections, the higher the permanent deformation. The existing pavement structures can serve for more than 20 years as per the MEPDG design analysis if the default failure criteria and nationally-calibrated models are used.     

Infilled Reinforced Concrete Beams for Sustainable Construction

This paper presents a study carried out on infilled reinforced concrete beams for sustainable construction. In reinforced concrete beams, less stressed concrete below neutral axis can be replaced by some light weight material to reduce the weight of the structure and also achieve the economy. The used infilled material is brick. Sustainability can be achieved by replacing the partially used concrete. By saving concrete, the authors save cement, which reduces the green house gases emissions. So it is considered as environment friendly. Since infilled beam acts like a layered member, there needs a theory to analyze it. Method of initial functions is used for the analysis of the infilled RC （reinforced concrete） beams. This method is successfully applied on infilled beam. Results show that physical conditions are verified for infilled beam.     

Economy of RHA （Rice Husk Ash） in Concrete for Low-Cost Housing Delivery in Nigeria

Delivery of housing units in adequate quantity and quality has been the pursuits of individuals and successive governments in Nigeria. Still, the gap between demand and supply is becoming wider on daily basis due to exorbitant cost of building materials that is beyond the reach of average Nigerians. Concrete being the most acceptable construction material is expensive due to high cost of cement. Efforts made to reduce the cost of cement were to no avail, thus there is need to look elsewhere. Past researches showed that substituting cement with 15% of RHA （rice husk ash） in concrete improves the performance of concrete and reduces global warming as a result of emissions from cement production. This paper looks into the effect of using RHA as partial substitute of cement on the cost of a low-cost housing unit. Results showed that cement based construction materials are responsible for 82.58% of the total cost in which cement is responsible for 42%. When 15% RHA was used to substitute cement over N90,000 was saved, amounting to about 7% of the total cost of the building. In addition, depletion of natural resources was reduced.     

Bending Stresses of Steel Web Tapered Tee Section Cantilevers

Although commonly used, no design method is available for steel web tapered tee section cantilevers. This paper investigates the bending stresses of such beams. Relationships between the maximum compressive stress and the degree of taper were investigated. An analytical model is presented to determine the location of the maximum stress when subjected to a uniformly distributed load or a point load at the free end and was validated using finite element analysis and physical tests. It was found that the maximum stress always occurs at the support when subjected to a uniformly distributed load. When subjected to a point load at the free end and the degree of taper is up to seven, it was found that Miller＇s equation could be used to determine the location of the maximum stress. However, it is shown that when the degree of taper is greater than seven, Miller＇s equation does not accurately predict the location and the analytical model should be used. It was also found that the location of the maximum stress was solely dependent on the degree of taper, while a geometric ratio, fl was required to determine the magnitude of the maximum stress. A simple method that predicts the magnitude of the maximum stress is proposed. The average error in the prediction of the magnitude of the maximum stress is found to be less than 1.0%.     

Probabilistic Seismic Hazard Assessment for Bridgetown-Barbados,Employing Subduction Interface Characteristic Earthquakes

A new probabilistic seismic hazard analysis was performed for the city of Bridgetown, Barbados, West Indies. Hazard computations have been performed using the standard Cornell-McGuire approach based on the definition of appropriate seismogenic sources and expected maximum magnitudes, the authors take into consideration the possibility of large subduction interface earthquakes of magnitude 8.0-9.0 beneath the Barbados accretionary prism via application of a characteristic model and slip rates. The analysis has been conducted using a standard logic-tree approach. Uniform hazard spectra have been calculated for the 5% of critical damping and the horizontal component of ground motion for rock site conditions setting 5 return periods （95, 475, 975, 2,475 and 4,975 years） and spectral accelerations for 34 structural periods ranging from 0 to 3 s. The disaggregation results suggest that the magnitude-distance pair that dominates the hazard yields M 7.4 and 8.6 and a distance of 42.5 km in the Interface Subduction Zone beneath Barbados for the 475 and 975 years RP （return period）, respectively. An event with an M 8.0 at a distance of 107.5 km in the Intraplate Subduction Zone is the second scenario that dominates the hazard for both 475 and 975 years RP.     

Sustainable Methods and Techniques in Old and New Public Constructions

This article is about the methods and techniques used in the building ＂retrofit＂ in modernist style designed by the architect Affonso Eduardo Reidy in the fifties, and also about the project of the new Rio de Janeiro MIS （Museum of Image and Sound）, under construction, by The North-American office Diller Scofidio ＋ Renfro, both located in the city of Rio de Janeiro. These constructions present a wide view of the concept of sustainability, not commonly used in public buildings in Brazil. In the building designed by Reidy, which belongs to the State of Rio de Janeiro, the regeneration to host the new headquarters of the State Department of Taxation and Finance respected its original characteristics and used smart and sustainable design techniques, as well as recyclable materials. On the other hand, the project of the new museum at Copacabana Beach was entirely planned on sustainable bases and it includes the application of building techniques concerning that purpose. This article presents a study of these two cases and evaluates the techniques and materials used in one another. Observing the principles of sustainability in construction is a pioneering initiative of the State Government. This article aims at making the scientific community aware of the needs of immediate adoption of sustainability techniques in Civil Engineering, not only in the construction of new buildings, but also in the regeneration of the existing ones, as well as the need of imperious adoption of sustainable techniques when it comes to maintainability.     

Social Participation in the Context of the Urban Public Space Renewal： The Case of Lagarteiro Neighborhood in Oporto

In 1980, Giancarlo de Carlo wrote in the Perspecta： Yale Journal, ＂An Architecture of the Participation＂. Carlo, proposed a sequence of procedures： the problem definition, the solution and the results evaluation, in all the three steps, the social communities should be integrated in as part of a share and dynamic process. This text corresponds to a new way of understanding the importance of the social communities in the architecture definition. From de Carlo＇s text, the main goal of this paper is to present the results of an intervention in public space renewal of the Lagarteiro neighborhood （in Oporto city） and the relation of this process with the participation of the resident population. The urban context of Lagarteiro＇s neighborhood presented before the intervention the typical and classic signs of disqualification of environmental and urban peripheral areas of resettlement. The term ＂disadvantaged areas＂ is associated with these areas in urban or peri-urban case, was framed in a specific Portuguese policy, called Initiative Critical Neighborhoods. Being a recent intervention, the renewal of the public space in Lagarteiro is a complete case study that allows comprehending the participation phenomenon in nowadays, at the same time that seduces a reflexion about technical and architectural solutions for ＂critical＂ neighborhood.     

Use of Geophysical Techniques for the Localization of the Restricting Zones of Permeability in the Bottom of Basin： Forecasting the Zones of Clogging

Measurements of dielectric parameters followed by permeability tests are performed on soil samples of infiltration basin. The dielectric parameters are obtained by TDR （time domain reflectrometry） measurements from which it is found that the measurement of the permittivity, the electrical conductivity and the relaxation time of compacted soil allows the mapping of the values of the coefficient of permeability at the surface of an infiltration basin. With the distribution of the coefficient of permeability, the areas of water stagnation can be detected before the basin filling. The study proves that the TDR measurements for the detection of these zones can be used for the management of infiltration basins for sustainable working and their remediation can be undertaken before the rainy seasons.