Name: how buildings handle structural movement
Uploaded: 2024-09-12T16:16:29.000Z
Duration: 1 min 27 s
Channel: JoVE

建物内のわずかな動きは、湿気にさらされた建物ユニットの拡張中、または凍結中に土壌中の水が膨張する基礎の上向きの隆起中に発生する可能性があります。
動きは建物に亀裂を形成する可能性がありますが、これを避けるために、作業ジョイント、構造エンクロージャジョイント、表面仕切りジョイント、建物分離ジョイントなどの移動ジョイントが設けられています。
作業ジョイントは、小さなストリップが重なり合うパターンで組み立てられ、わずかな動きを苦痛なく許容する瓦礫屋根で使用されます。
空洞壁において、棚角の下に設けられたソフトジョイントが非構造外部ワイスを支持する構造エンクロージャジョイントの一例である。
サーフェス ディバイダー ジョイントには、アイソレーション ジョイント、伸縮ジョイント、および制御ジョイントが含まれます。
既存の建物に新たな追加を行うと、アイソレーションジョイントが提供され、既存の建物に影響を与えることなく新しい材料を移動させることができます。
伸縮継手は建材の膨張を可能にするように設計されたオープンスロットであり、制御継手は建材が収縮するときに亀裂が発生する可能性のある場所に作成される弱点の線です。
最後に、建物分離ジョイントは、複雑な建物構造を、互いの動きから独立できる個別のセグメントに細分化します。

建物の可動ジョイント

建物の可動ジョイントは、温度変化、水分含有量の変化、構造のたわみなど、さまざまな要因によって生じる避けられない動きに対応する重要な設計要素です。これらの動きは、設計と建設で考慮されていない場合、見苦しい、または危険な損傷につながる可能性があります。可動ジョイントは、これらのストレスを管理し、材料が損傷を引き起こすことなく移動できるようにするために、さまざまな形で組み込まれています。

最も単純なタイプの可動ジョイントであるワーキングジョイントは、建設プロセス中に統合されます。例としては、熱と湿気の動きを可能にする屋根瓦や木製のベベルサイディングがあります。構造/エンクロージャジョイントは、金属フレームの壁のたわみトラックや石積みベニアを支える棚角度の下のソフトジョイントなど、損傷を引き起こす可能性のある荷重の伝達を防ぐために、構造要素と非構造要素を分離します。

分離ジョイントは、改修やコンクリートスラブが構造要素と接する場所で一般的に見られる、独立して移動する必要がある材料間の干渉を防ぐために使用されます。制御ジョイントは、コンクリートの歩道や石膏ボードでよく見られるように、あらかじめ決められた線を作り、制御された方法でひび割れを誘導します。伸縮ジョイントは、レンガの壁やカーテンウォール システムに見られるように、材料の伸縮に対応します。

最後に、建物の分離ジョイントは、複雑な構造を独立して動くセグメントに分割し、容積変化ジョイント、沈下ジョイント、地震分離ジョイントに分類され、それぞれが特定の構造的動きの課題に対処します。

建物内のわずかな動きは、湿気にさらされた建物ユニットの拡張中、または水が水にさらされたときの基礎の上向きの隆起中に発生する可能性があります...

Education

JoVE Core

Civil Engineering

土木工学

Unit 1

ユニット1

Masonry

組積造

KEY TERMS AND CONCEPTS

主要用語と概念

Movement Joints in Buildings

how buildings handle structural movement

Buildings are designed to handle movement from temperature changes, moisture changes, and structural deflection. If these changes are ignored, they can cause visible damage or even unsafe conditions. Movement joints give building materials room to move without creating distress.

Working joints are the simplest type. They are placed during construction and help materials cope with change as the building goes up. Shingled roofs and wood bevel siding are common examples because they can move with thermal and moisture changes.

Some joints separate parts of the building so loads do not transfer where damage could happen. These are structure/enclosure joints. In metal-framed walls, deflection tracks help with this kind of movement. Soft joints under shelf angles that support masonry veneer also reduce stress between structural and nonstructural parts.

Isolation joints keep materials that need to move on their own from interfering with each other. They are often used in renovations or where a concrete slab meets a structural element. Control joints work differently. They create a planned line of weakness so cracking happens in a controlled way, such as in concrete sidewalks and plaster walls.

Expansion joints allow building materials to expand and contract. They are often seen in brick walls and curtain wall systems. Building separation joints divide a large structure into sections that can move independently. These include volume-change joints, settlement joints, and seismic separation joints, which each address a different kind of movement problem.

How Buildings Handle Structural Movement

composite masonry walls

Bonding and Materials in Composite Masonry

Composite masonry walls use two or more wythes, or vertical layers, of masonry to form one unified wall. The wythes may use the same material or different masonry materials. They are joined to work together as a single structure. These wythes can be bonded in several ways. Builders may use mortar-filled collar joints, grouted spaces, or rigid metal ties with reinforcement. Masonry header units can also connect the layers, but this method is rare. Metal ties are often preferred because they...

masonry cavity walls

Masonry Cavity Walls and Moisture Control

Masonry cavity walls use two wythes, or layers, with a hollow space between them. The outer and inner wythes are linked only by corrosion-resistant metal ties. This design helps manage water and improve wall performance. When rainwater passes through the outer wythe, it moves down through the cavity. Flashing catches the water and directs it toward weep holes, where it can leave the wall. The inner wythe often has damp-proofing on the cavity side. This layer also works as an air barrier. The...

masonry loadbearing walls

How Masonry Walls Support Buildings

Masonry load-bearing walls support floors and roofs and carry those loads down to the foundation. They are built from brick, stone, or concrete masonry units. These walls rely on compressive strength, which means they can resist pushes from above very well. Masonry walls may be reinforced or unreinforced, depending on the building needs. They carry dead loads and live loads while using working stresses that stay below the materials' ultimate strength. That safety margin helps the structure...

masonry curtain walls

Masonry Curtain Walls and Support Systems

Masonry curtain walls use brick or stone veneer as an exterior cladding system. The veneer is supported by the building structure, so the wall can be both attractive and functional. Two main construction methods are used for these walls. One method builds the masonry units in place through traditional layering. The other uses prefabricated panels that are assembled on the ground and then lifted into position. In traditional construction, steel shelf angles attached to the spandrel beam carry...

posttensioned masonry walls

How Masonry Walls Gain Extra Strength

Post-tensioned masonry walls gain extra strength from high-strength steel rods or flexible tendons. These tensioning elements are anchored to the foundation and run vertically through the wall. In some walls, they sit inside the cores of the masonry units. In others, they are placed between the masonry wythes, or layers. The wall is built first with the tensioning elements already in place. After the mortar cures fully, the wall is tightened. Steel rods are tensioned by turning nuts against...

cavity drainage and flashings in masonry walls

cavity-drainage-and-flashings-in-masonry-walls

Moisture Control in Masonry Cavity Walls

Masonry cavity walls use a gap between two wythes, or wall layers, to help control moisture. The cavity is usually at least 2 inches wide, and it may contain insulation. Even with insulation, a clear space of at least 1 inch is kept so water can drain away. Some walls also use a continuous drainage mat to reduce the needed space while still moving moisture out. Weep holes are another key part of cavity drainage. These openings sit at the base of the cavity and let collected water escape. They...

thermal insulation in masonry walls

Masonry Wall Insulation Options

Masonry wall insulation can be placed on the outside, inside the wall, or on the interior surface. The best choice depends on the climate, the building design, and whether the wall is being built new or retrofitted. In hot, dry climates, masonry can help smooth indoor temperatures by absorbing heat during the day and releasing it at night. In many other climates, extra insulation is needed to improve thermal resistance. One common exterior method is an Exterior Insulation and Finish System, or...

expansion and contraction in masonry walls

expansion-and-contraction-in-masonry-walls

Masonry Wall Joints for Temperature and Moisture

Masonry walls change size slightly as temperature and moisture change. Builders account for this movement so the wall does not crack or shift out of place. Thermal movement is usually easy to measure and plan for. Moisture movement is harder to predict. New clay masonry units often absorb water and expand over time in normal outdoor conditions. New concrete masonry units behave differently. They usually shrink as they lose extra moisture gained during production. These opposite changes make...

movement joints in buildings

Buildings are designed to handle movement from temperature changes, moisture changes, and structural deflection. If these changes are ignored, they can cause visible damage or even unsafe conditions. Movement joints give building materials room to move without creating distress. Working joints are the simplest type. They are placed during construction and help materials cope with change as the building goes up. Shingled roofs and wood bevel siding are common examples because they can move with...

types of building separation joints

Building Joints for Movement and Stability

Building separation joints help large or complex buildings move in a controlled way. They split a structure into smaller, separate units. This reduces stress when the building shifts under different forces. The joints are grouped into three main types: volume-change joints, settlement joints, and seismic separation joints. Volume-change joints handle expansion and contraction caused by temperature changes and moisture changes. They are placed where the building mass has discontinuities,...

efflorescence in masonry

Stopping White Salt Crystals on Masonry

Efflorescence is the white, fluffy crystal layer that can form on masonry walls. It happens when water-soluble salts in brick, stone, concrete, or mortar are dissolved by water and carried to the surface. When the water evaporates, the salts are left behind as a powdery deposit. New efflorescence is often seen soon after construction. In many cases, it can be cleaned with water and a brush. It may also fade over time as rain leaches salts out of the masonry surface. If efflorescence appears...

mortar joint deterioration in masonry

Repairing Damaged Mortar Joints in Masonry

Mortar joints in masonry can break down when water collects in them and freezes. The repeated freezing and thawing makes the water expand and shrink. That process creates cracks in the joints and can spread damage over time. As the mortar worsens, pieces may spall, or break off from the joint surface. Loose masonry units can follow, and the wall becomes weaker. Damaged joints also let moisture move into the wall, which adds to the problem. Good construction helps protect mortar joints. Using...

masonry in cold and hot weather conditions

masonry-in-cold-and-hot-weather-conditions

Protecting Mortar During Weather Changes

Masonry work changes in cold and hot weather because mortar must stay at the right temperature and moisture level. If mortar freezes before it cures, its strength and watertightness can drop. For proper hydration and curing, mortar should stay between 60°F and 80°F. When the weather is below 40°F, the water used for mortar must be heated. The water should not exceed 120°F, because very hot water can reduce compressive strength and bond strength. Masonry units and sand should also stay dry and...

masonry paving

Masonry Paving Materials and Base Layers

Masonry paving uses bricks, stones, and concrete masonry units to create durable walking and driving surfaces. These materials are selected for their shape, color, strength, and resistance to abrasion and weathering. Masonry units can be used in different paving setups depending on the site and the load they must carry. Some paving systems are installed dry on a thin sand layer over a gravel base. Others are set in mortar or asphalt on a concrete slab. For areas with heavy vehicular loads, a...

key terms and concepts

Learn how movement joints help buildings handle temperature, moisture, deflection, and cracking with examples from roofs, walls, masonry, and concrete.

How Buildings Handle Structural Movement | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

How Buildings Handle Structural Movement

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