Characteristics of the Architectural Structures Belonging to the Transition Period in Beirut (1840-1920)

Conserving the architectural structures of heritage buildings has become an important issue in Beirut. It is the result of necessary retrofit of existing traditional bourgeoisie architecture of 19th century, belonging to the late Ottoman period, recognizing the importance of its traditional technics and to keep them in use. Although, they have been subjected to lack of maintenance and repair which led to processes of severe degradation, compromising their use, it allows now a deep observation of their characteristics. The main goal of this article is: to outline the evolution of the construction of this late Ottoman Heritage;characterize its architectural typology;understand the impact of Building Codes;and present results of surveys. For the analysis, non-destructive methods were performed. The survey of three case studies according to a pre-selection of representative Ottoman buildings (1840-1940) is presented. This intends to contribute for the conservation of Beirut traditional housing and give useful technical information.

High Strength Low Alloy (HSLA) Steels in Building Construction

Majority of the buildings,including industrial buildings,are constructed using either structural steel (plates and structural shapes) or deformed bar steel reinforced concrete.Such buildings,however,must be designed to be safe and serviceable during construction and during use and occupancy.These objectives can be easily achieved by the use of steels having superior mechanical properties,ductility,weldability,fire resistance,etc.Over the years,the steel industry has made improvements in steel making technologies resulting in high strength low alloy (HSLA) steels with superior steel properties well suited for building construction.First part of this paper presents the structural design considerations,and the constructional considerations associated with the building structures in general,and steel structures in particular.This second part of the paper looks at the acceptance criteria for HSLA steels for North American building codes and construction.The third part of the paper presents the structural properties of currently available HSLA steels for building construction.The discussion focuses on hot-rolled structural steel shapes as well as deformed steel bars for concrete reinforcement.The paper argues that Niobium microalloying is the key to achieving superior properties in such steels.

Influences of Shrinkage,Creep,and Temperature on the Load Distributions in Reinforced Concrete Buildings During Construction

Site measurements have shown that slab loads re-distribute, between the slabs during the concrete curing, while the external Ioadings and structural geometry remain the same. Some have assumed that this is caused by concrete shrinkage and creep, but there have been no studies on how these factors exactly influence the load distributions and to what degree these influences exist. This paper analyzes the influences of concrete shrinkage, creep, and temperature on the load re-distributions among slabs. Although these factors may all lead to load re-distribution, the results show that the influence of concrete shrinkage can be neglected. Simulations indicate that shrinkage only reduces slab loads by a maximum of 1.1%. Creep, however, may reduce the maximum slab load by from 3% to 16% for common construction schemes. More importantly, temperature variations between day and night can cause load fluctuation as large as 31.6%. This analysis can, therefore, assist site engineers to more accurately estimate slab loads for construction planning.

Load Distribution Assessment of Reinforced Concrete Buildings During Construction with Structural Characteristic Parameter Approach

High-rise reinforced concrete buildings are in great demand in developing countries with rapid urbanization. Construction engineers are facing more and more safety control challenges. One major issue is the understanding of the load distributions, especially the maximum slab load, of structures under construction, which is time dependent. Previous methods were mainly targeted to specific examples, providing specific solutions without addressing the fundamental issues of finding general solutions for load distributions in reinforced concrete buildings with different geometrical and material characteristics during construction. The concept of a structural characteristic parameter is used here to parametedze the main geometrical and material characteristics of concrete structures for generalized assessments of load distributions during construction. The maximum slab load for 20 different construction shoring/reshoring schemes is presented. The results indicate that the traditional simplified method may underestimate or overestimate the maximum slab load, depending mainly on the shoring/reshoring schemes. The structural characteristic parameter approach was specifically developed to assist construction engineers to estimate load distributions to assure safe construction procedures.

Defects in Concrete Elements: A Study of Residential Buildings of 30 Years and above in Onitsha Metropolis, Anambra State, Nigeria

Building defect is an issue in existing buildings that needs urgent tackling to prevent further problems. This study assessed the defects in concrete elements in residential buildings of 30 years and above in the Onitsha metropolis of Anambra State, Nigeria. Data collection instruments in the study include structured questionnaire, interviews, visual inspection/observations, archival records, recordings, photographs;and non-destructive testing of the concrete elements in an existing building in the study area. The population of this study constituted of the construction registered professionals and the existing buildings in study area. The sample for the study was based on the calculated sample size using Taro Yamani Formula. A total of 158 registered professionals were sampled from the population of 260. The questionnaires were purposively distributed to the registered professionals up to the required sample sizes of 158 and 129 questionnaires were properly filled and returned. The study used the SPSS and Microsoft Excel to analyze the data. The results were analyzed in percentages and figures using descriptive statistics and presented in the form of pie charts and tables. The finding of the study revealed that the causes and effects of structural defects on the concrete elements in existing buildings in the study area according to the rating are;exposed/corrosion of the embedded metals, faulty workmanship, overload and impacts, chemical attack, freeze-thaw deterioration, fire/heat, restraint to volume change. The visual observation revealed that the structural elements are characterized by heavy defects such as deep vertical, horizontal and diagonal cracks, exposed/ corrosion of the embedded metals, spalling of the concrete slabs. The existence of defects in the concrete members led to the low compressive strength of the concrete elements and the structural instability of the existing buildings as revealed by the non-destructive test. The non-destructive test result revealed that most of the tested concrete elements have low compressive strength value and such were remarked poor as they did not satisfy the assumed value. Essentially, the study concluded by recommending that regular monitoring, inspections and non-destructive testing of concrete elements should be conducted on existing aged and defected buildings to detect the structural stability of the buildings;and it is imperative to evacuate occupants from heavy structurally deteriorated and defected buildings since most of them have lost their residual design life span and ability to sustain imposed loads.

装配式建筑结构顶升逆作法原理与技术发展

顶升逆作法综合了顶升和逆作法两种技术的不同特性,是一种在邻近地面对建筑逐层建造并逐层顶升的新型建造工艺。通过对顶升各阶段的原理分析,结合强时变结构特点,对顶升点选择等关键技术进行研究,分析了竖向顶升位移不同步工况下的结构受力机理,厘清了装配式建筑结构顶升逆作法的受力特点,梳理了现有的相关配套技术,指出了目前装配式建筑结构顶升逆作法待解决的技术难题。针对新型建造工艺的强时变特征,提出了结合数字孪生和人工智能两种技术进行智能调控的发展趋势,构建了面向减碳优化的综合目标函数,并通过算例证明合理的顶升方案对减少建造阶段构件内力的作用。结果表明:依托装配式建筑结构顶升逆作法原理,采用机械化施工取代人工作业、大重量顶升替换高空吊运,减少设备的层间转运和材料的竖向运输,能够在提高施工建造效率的同时,将工艺流程控制在临近地面的有效高度范围内,有望降低环境影响、减少碳排放、提高建筑结构在未来服役末期的资源化可行性,助力建筑业绿色低碳发展。

装配式配筋砌块砌体结构技术与应用

当前在国家大力倡导建筑业采用装配化建造方式的背景下,装配式混凝土结构、装配式钢结构等建筑新技术不断涌现并在工程建设中大量应用,而砌体建筑在这次装配化建造大潮中比较沉寂。砌体结构领域的工作者一直也在积极探索,介绍了砌体结构中一种配筋砌块砌体结构实现装配化建造的技术,该技术先以标准化生产的砌块产品组装成个性化需求的墙构件,再将墙构件经绑扎后在施工现场吊装并在安装中穿入竖向钢筋,最后用混凝土灌孔连接形成整体结构。该技术是基于理论试验研究及工程实践验证后得出的新成果,已有近20万m^(2)规模的工程实践应用,具有成本低、工艺简、安全性好、效率高等特点,为采用装配化方法建造房屋提供了新的选择。

甘肃积石山地震村镇典型建筑震害及成因分析

2023年12月18日甘肃省临夏回族自治州积石山发生6.2级地震,此次地震造成了大量的村镇建筑破坏和倒塌,并造成了多人伤亡,是典型的“小震大灾”。文中总结了积石山地震中震区村镇建筑典型震害特点和规律,并结合建筑的结构类型、建造年代和是否具有抗震构造措施进行了典型案例分析,总结此次地震震损较为严重的原因:部分自建房屋为砖柱和土坯墙,二者缺乏有效连接,自身抗震能力差,这点从同一院落具有圈梁构造柱的房屋基本完好而不具备抗震构造措施的房子破坏严重可以说明;部分房屋不同层存在开间变化导致竖向传力不连续;结构存在大量平面布置不规则的情况;结构局部不完整或存在薄弱部位;农村自建房屋,按照工匠习惯建设,未考虑地震作用下的受力要求,需要建立质量监管体制机制。

甘肃积石山6.2级地震村镇建筑震害调查与分析

积石山地震对甘肃和青海部分地区房屋建筑造成了严重破坏。调查了地震烈度7度和8度地区的11个调查点的村镇建筑震害。震害调查表明:地震灾区主要为乡镇和农村地区,房屋结构类型主要为土木、砖木和未设防砖混结构;在烈度8度地区,土木结构房屋主要表现为严重破坏或倒塌破坏,砖木结构和未设防砖混结构房屋主要表现为中等破坏和严重破坏,设防砖混和钢筋混凝土框架结构房屋主要表现为轻微破坏和中等破坏;在烈度7度地区,土木结构房屋以中等破坏为主,砖木结构和未设防砖混结构房屋以轻微破坏和中等破坏为主,设防砖混和钢筋混凝土框架结构房屋以轻微破坏和基本完好为主。此次地震震害较同级别地震偏重,与震区复杂地形、地震动峰值放大效应、建筑砌筑质量差和结构受力不合理等因素相关。建议进一步开展复杂地形场地放大效应及频谱影响研究,重视建筑非结构构件抗震宣传与实用技术研发。

新质生产力背景下装配式钢结构建筑标准化施工策略研究

随着新质生产力的快速发展,装配式钢结构建筑作为一种绿色、高效的建筑方式,正逐渐受到广泛关注。本文在分析了其优势与面临的挑战后,提出了新质生产力背景下装配式钢结构建筑的标准化施工策略,为相关领域的实践和研究提供参考。

基于MBD的高层建筑施工工艺结构化表征

针对高层建筑施工过程中的庞大内容和复杂的组织关系,本文首先深入分析了二维纸质工艺图纸和文件作为技术交底形式所带来的抽象性、理解困难、规范性差及数据一致性难以保障等问题。基于对高层建筑施工工艺特性和信息集成需求的分析,本文规范化定义了施工工艺的要素和属性,提出了基于工艺结构树的施工工艺信息组织管理方法,并构建了多层级工艺信息模型以实现工艺信息的结构化表达。借鉴制造业的MBD理念,本文以工艺结构树为数据组织核心,结合BIM模型与工艺信息卡片,提出了集成几何设计与施工工艺信息的三维施工工艺结构化表征框架。最后,通过开发交互式作业指导系统并结合实际案例验证,完成了项目主体、工艺和各类资源的有序整合,为智能建造提供了理论与方法支持。

晋东南地区农村装配式技术常见问题及措施初探

近几年,随着装配式建筑的一步步推进,装配式结构不仅在城市内民用建筑中大量使用,而且发展到了农村建房中。晋东南地区农村装配式建筑取得了一定突破,但是在实际设计施工当中仍然存在一些不足,因此,针对目前装配式建筑生产设计施工中的常见问题提出一些改进,以促进晋东南地区农村装配式建筑的施工质量的进一步发展。

超高层建筑钢结构施工的关键技术和措施

随着城市化的不断推进,超高层建筑的兴建成为城市发展的一种趋势。在超高层建筑中,钢结构因其轻质、高强度等特点,成为超高层建筑的首选方案。文中通过对钢结构特征的分析,深入剖析了超高层建筑中的钢结构施工流程及影响因素。在此基础上,详细讨论了柱基础检查、钢柱吊装和钢柱连接等关键技术与应用措施,包括了施工过程中的质量监控、安全管理和技术检测等方面,旨在为超高层建筑钢结构施工提供可行的解决方案。

大型压缩空气储能系统的土木工程建筑结构设计优化

大型压缩空气储能系统的土木工程建筑结构设计优化是确保系统安全、稳定、高效运行的关键环节。本文围绕该主题,从热力学储能作用分析、设计目标、子系统设备选型三方面着手,对大型压缩空气储能系统进行建模。通过对设计方法的梳理与分析,指出了其中存在的不足之处,如建筑结构储气量较少、储能量不达标、选址不够灵活。针对这些问题,提出了一系列优化设计措施,包括结构设计、材料选择、施工技术和环境适应性等。

装配式混凝土建筑施工现场群塔布置的影响因素分析

装配式混凝土建筑的预制构件类型繁多、数量大,现场吊装作业任务量大。装配式混凝土建筑施工现场进行群塔布置时需要考虑塔吊的选型、施工场地和道路情况、塔吊的站位和群塔作业防碰撞要求等因素。在保证群塔施工中相互运行安全的前提下,群塔的合理布置应可最大限度地提高群塔利用效率,满足施工要求。

轻钢结构建筑物化阶段碳排放及减排的研究

建筑行业碳排放量占社会碳排放总量的40%左右,其中,建筑物化阶段的碳排放总量最大,且强度高,该阶段碳减排是建筑减排的重要突破口。目前,大部分建筑减排研究主要针对传统现浇钢筋混凝土建筑,对于轻钢结构建筑的研究较少,针对轻钢建筑物化阶段碳排放的研究更少。本研究构建了轻钢建筑物化阶段碳排放计算模型,选取北京某轻钢结构建筑为案例,通过计算物化阶段的碳排放,分析建材生产、运输、施工建造各阶段的碳排放,发现轻钢结构建筑在各阶段有较大的减排潜力,并提出相应的减排措施。

关于绿色建筑在装配式建筑结构中的应用

建筑项目内部通常会涉及大量专业知识,包含多类施工技术,施工期间会消耗诸多资源,产生各类建筑垃圾,污染周围环境。在绿色建筑背景下,装配式建筑的建设规模越来越大,通过采取绿色施工技术和方法,能够更好保护环境,节约资源。本文详细分析绿色建筑背景下装配式建筑的特点,提出结构施工技术要点,获得比较好的成效,以期为相关人员提供参考。

高层装配式钢结构住宅施工设计及关键技术研究

以济南先行区绿色建设国际产业园租赁住房项目为工程背景,研究了高层装配式钢结构住宅设计及施工关键技术。通过研究基于BIM技术构件深化设计、施工顺序优化、防火体系优化、外墙防水体系优化等关键技术,确定了最优施工技术,在不增加成本及工期的基础上,提高了建筑整体及局部防火、防水性能。通过研究地脚预埋、钢梁、钢柱及附属结构的施工关键技术,确定了各施工步骤最优技术,确保了施工安全及质量。基于研究成果,形成了一套综合性的高层装配式钢结构住宅技术体系,结果表明:研究成果的应用提高了工程质量及经济效益,缩短了施工工期。

双塔高层悬垂屋面施工模拟研究

采用有限元对双塔高层悬垂屋面构件的变形效应进行施工全过程模拟分析,探究其支承结构和永久结构在分析过程中的力学转换关系,并根据施工模拟结果确定最终施工方案。该文重点介绍施工模拟过程中的一些思路及探讨,如分析悬垂屋面安装及卸载工序,以及从结构变形、杆件内力及稳定性方面对其安全性做出评估等,得出的结论可为现场施工提供有效指导,以期为后续类似双塔高层悬垂屋面的施工方案积累实践经验。

优秀历史建筑的结构加固与风貌修缮施工技术

结合上海东长治路505号优秀历史建筑装修(修缮)施工,针对施工过程中遇到的拆除加固与修缮方面难题,采用了划分区域的主体结构增大截面加固措施,既提高了保护建筑的承载能力及抗震性能,又避免了对原有结构的破坏。同时应用了针对不同病害的保护建筑修缮施工措施,通过对内饰和外饰材料的清洗修补,还原了建筑的古锈肌理,使百年历史建筑焕然一新,实现了加固修缮工程的高效、高质、环保施工。