Lightweight Concrete Slabs Research Articles

Ties for cavity walls and masonry cladding

Reviews the history of the development of cavity wall ties, particularly in relation to their durability, and covers recent improvements in both materials specifications and performance. Describes newer forms of tie and illustrates those suitable for fixing new masonry to timber, concrete, steel and lightweight concrete slabs or blockwork as well as alternatives to the traditional tie types. Discusses products installed in existing walls to deal with problems such as corrosion of original ties, insufficient provision, or ties of the wrong specification.

Punching Shear Behavior of Lightweight Concrete Slabs and Shells

Results of an experimental investigation of the punching shear strength of reinforced and prestressed lightweight concrete slabs and shells representative of the exterior walls of offshore structures are summarized. Eight continuous slabs, one single-span slab, and six single-span shells were tested. The main variables investigated were amount of shear reinforcement, shell curvature, prestressing, span continuity condition, and size of loaded area. The punching shear strengths observed were much higher than those predictied by the 1983 ACI Building Code (ACI 318-83), particularly in the specimens with shear reinforcement and curvature. The higher strengths were primarily a result of the following: the relatively small span-to-thickness ratios of the specimens; superior performances of the headed shear reinforcing bars used in the study when compared to conventional stirrups; and the presence of arch action produced by shell curvature.

DRYING LIGHT-WEIGHT CONCRETE SLABS

To study unsteady state problems of heat and mass transfer in concrete pavements, which are generally considered to be fine porous media, both relevant material characteristics and transport properties must be considered simultaneously. A system of nondimensional differential equations for heat and mass transfer in porous media is derived and used to investigate the drying history of moisture content in a particular light-weight concrete slab. An implicit finite difference numerical scheme is employed for obtaining the numerical results. The results show that the Lewis number Le, Bi h number Bi m play an essential role in the simultaneous mass and heat transfer.

A Stub-Girder System for High-Rise Buildings

The current trend to "systems" design in building construction has necessitated a new interdependence between the owner, architect, structural engineer, mechanical and electrical engineer, and the contractor. This paper describes one of the new systems—the integration of the mechanical ducts into the structural steel floor beams of a high-rise building. This system is called a stub-girder system. A conventional system of framing a floor in a structural steel structure is shown in Fig. 1(a). The structural system consists of wide flange beams spaced between 7 ft-0 in, and 11 ft-0 in. apart. The floor slab consists of approximately 3.25 in. of lightweight concrete on a metal deck. Composite action between the steel beams and the concrete slab is generally achieved by the use of suitable shear connectors. The mechanical ducts, lights, and ceiling construction are generally placed under the beams. In some instances, penetrations are made in the beams and girders to accommodate the ducts. For a building having a span of 40 ft-0 in. between the core and the exterior columns, the distance between the top of the floor slab and the ceiling is approximately 4 ft-0 in. The stub-girder system is shown in Fig. 1(b). The system consists of a girder spaced approximately 30 ft-0 in. on centers and spanning between the core and an exterior column. This girder consists of a high-strength, wide flange beam with stub pieces shop-welded on the top flange. Floor beams are placed over the girder (between the stub pieces) at approximately 10 ft-0 in. on centers. The floor beams are designed for continuity and are spliced near the points of inflection. The system is completed by the placement of a lightweight concrete slab on metal deck spanning between the floor beams. Composite action is ensured by the provision of shear connectors. The girder is shored while the concrete reaches its design strength.

Lightweight Concrete-on-Steel Composite Beams

Current design specifications for composite beams include no provisions for beams with lightweight concrete. Conceptually, the use of lightweight concrete for composite beams can lead to greater economy, since a substantial reduction in dead load can be obtained. However, there have been some questions regarding the use of lightweight concrete in composite construction. Six composite beams with lightweight concrete slabs were tested and the results compared with a previously developed theoretical analysis. The theoretical analysis was then used to study the effects of partial shear connection, modular ratio, and unshored construction on the behavior of composite beams.

Fire Endurance of Simply - Supported Prestressed Concrete Slabs

SYNOPSIS Fire tests were conducted on eleven pretensioned prestressed concrete slab specimens. Variables included thickness of cover (1, 2, and 3 in.), type of concrete (normal weight and lightweight), strand size ( 1 /4 and 'he in.), and load intensity (40 to 60 percent of calculated ultimate moment capacity). All slabs were 6.5 in. thick and 27.4 in. wide and were fire-tested while simply supported on rocker-roller bearings. Results indicate that fire endurance is improved by increasing the cover thickness and reducing the load. The lightweight concrete slabs had longer endurance periods than comparable normal weight concrete slabs. A method of estimating the fire endurance of simply-supported prestressed concrete slabs is presented.

1041 生コンによる人工軽量骨材コンクリートの品質について

1041 生コンによる人工軽量骨材コンクリートの品質について

1042 デツキプレートを使用した軽量鉄筋コンクリート床版構法の研究 : その1. 構法について

1042 デツキプレートを使用した軽量鉄筋コンクリート床版構法の研究 : その1. 構法について

1043 デッキプレートを使用した軽量鉄筋コンクリート床版構法の研究 : その3. 耐火試験について

1043 デッキプレートを使用した軽量鉄筋コンクリート床版構法の研究 : その3. 耐火試験について

Composite Beams of Steel and Lightweight Concrete

Since publication of the 1961 AISC Specification, interest in composite design has grown. Concurrent with this growth in interest has been the development of new types of shear connectors and the use of composite design with lightweight concrete floor slabs. Data from tests on lightweight aggregate concrete composite beams was not available in 1961 when the current AISC Specification was developed. Since that time tests have been run on beams with lightweight concrete, with satisfactory results. This paper has a twofold purpose: to discuss a general method of evaluating composite beam tests, and to review the data on the effectiveness of shear connectors in lightweight concrete composite beams.

2150 補強ALC版の曲げ性状について (比重0.6〜0.7の場合)

2150 補強ALC版の曲げ性状について (比重0.6〜0.7の場合)